All objects consist of atoms, which are made up of protons and neutrons in the atomic nucleus, surrounded by electrons. Once one enters this universe of the smallest things – the quantum world – it all gets very complicated very quickly. When researchers want to know exactly how atoms are connected and form solid objects, they come up against limits. No computer is powerful enough to calculate material properties precisely when many different atoms are involved. A researcher from the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) has now investigated a way to do this via digital quantum simulation. This requires a quantum computer with initially only a few functioning computing and memory units, qubits, which could already answer questions about materials research – using quantum computing to ultimately even improve itself."In contrast to problems that can be solved with increased computing power alone, the complexity of quantum systems exceeds the capabilities of all supercomputers available today, combined. This means that we are currently unable to find explanations for phenomena from the quantum world, including conductivity, magnetism and superconductivity," says Benedikt Fauseweh from the <a href="https://www.dlr.de/en/sc" target="_blank">DLR Institute for Software Technology</a>. "Quantum physics is fundamental to understanding our world, especially solid-state physics." In solids, atoms or molecules are so close together that they hardly move at all. Metals, semiconductors, ceramics and many plastics are solids.<h2>A visionary idea – but quantum computers still make mistakes</h2>The concept of simulating quantum phenomena on a quantum computer is more than 40 years old. In 1982, the US-American physicist Richard Feynman (1918 to 1988) proposed using the principles of quantum mechanics itself to simulate the behaviour of quantum systems. “The development of modern quantum computers is bringing Feynman’s visionary idea closer to reality. Of course, it remains the dream of all physicists to describe all of nature in its full complexity,” says Fauseweh. But we are not there yet; quantum computers still make errors in complex calculations because their qubits (computing and storage units) are not stable or cannot be controlled, leading to incorrect results. Nevertheless, researchers are looking for ways to run sophisticated simulations on quantum computers.<h2>Large number of qubits not required</h2>Fauseweh has described this in the scientific journal <a href="https://www.nature.com/articles/s41467-024-46402-9" target="_blank" rel="noopener noreferrer">Nature Communications</a> and included worldwide research results. His analysis shows that a large number of qubits is not necessarily required for the simulation of complex quantum systems: "If we use too many qubits, the results are no longer useful due to errors in the quantum computer," explains Fauseweh. "We have to identify precisely those applications that still deliver a correct result even with errors in the quantum computer." So, with quality before quantity, digital quantum simulations could soon solve the mysteries of solid-state research: why do interactions between many particles prevent their movement in solids? Why, for example, do some materials not heat up as expected in a magnetic field? How do materials change their properties when they are irradiated with lasers? "It is also exciting that we can use quantum computers in materials research to make quantum computers themselves better."Different technologies for quantum computers certainly complement one another.<a href="https://www.dlr.de/en/latest/news/2022/03/computing-with-light" target="_blank">&nbsp;Photonic quantum computers</a> or quantum computers with <a href="https://www.dlr.de/en/latest/news/2023/02/atomic-shells-become-computational-building-blocks" target="_blank">neutral atoms</a>, for example, would be particularly suitable for some applications, while quantum computers with<a href="https://www.dlr.de/en/latest/news/2022/04/contract-awarded-as-part-of-the-dlr-quantum-computing-initiative" target="_blank">&nbsp;ion traps</a>, with <a href="https://www.dlr.de/en/latest/news/2022/04/how_diamonds_become_qubits" target="_blank">nitrogen vacancies in diamond</a> or other <a href="https://www.dlr.de/en/latest/news/2023/04/quantum-computers-out-of-the-lab-into-the-world" target="_blank">solid-state spins</a>, would suit others. These hardware technologies are being developed in the <a href="https://www.dlr.de/en/research-and-transfer/featured-topics/quantum-technologies/the-dlr-quantum-computing-initiative-qci" target="_blank">DLR Quantum Computing Initiative (DLR QCI)</a>.<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1712996854792-image-1920-0e0e1372dc051ff5fc2e347f9452228c.jpeg" style="width: 100%px;" class="fr-fic fr-dib">Goal – improving materials. Quantum computers can simulate solid-state structures that even the best supercomputers cannot calculate. They can therefore help to improve materials for high-tech applications such as photovoltaic systems. Credit: © DLR. All rights reserved<h2 id="isPasted">Analogue simulations reach their limit</h2>In recent decades, researchers have used analogue quantum simulations to assist them – with a quantum platform that serves as a substitute for the actual system. The behaviour of the substitute quantum platform is adjusted so that it corresponds to that of the system under investigation. In this way, it is possible to simulate quantum systems that supercomputers had already failed to – and with this the advantages of quantum simulation become apparent. Analogue quantum simulation has been a common method until now. "However, it has the disadvantage that these machines are not flexible. They can only do one type of simulation," says Fauseweh. "What we want is the universality of a digital quantum computer. That is the most important advantage we expect from the different approaches."

Crystal lattice of a solid (symbolic image). When researchers want to know exactly how atoms are connected and form solid objects, they come up against limits. Digital quantum simulations could soon solve the mysteries of solid-state research. Credit: stock.adobe.com

Digital quantum simulations can be used to solve problems in solid-state research, for example conductivity, magnetism or superconductivity.

Quality matters - Advances in digital quantum simulation

Through steady advances in the development of quantum computers and their ever-improving performance, it will be possible in the future to crack our current encryption processes. To address this challenge, researchers at the Technical University of Munich (TUM) are participating in an international research consortium to develop encryption methods that will apply physical laws to prevent the interception of messages. To safeguard communications over long distances, the QUICK³ space mission will deploy satellites.<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1711154269577-csm_m241121013_ATOMIQS_Copyright_JensMeyer_UniversitaetJena_01_393047fa55.webp" style="width: 100%px;" class="fr-fic fr-dib">Tobias Vogl investigates single photon sources in 2D materials in an experimental setupHow can it be ensured that data transmitted through the internet can be read only by the intended recipient? At present our data are encrypted with mathematical methods that rely on the idea that the factorization of large numbers is a difficult task. With the increasing power of quantum computers, however, these mathematical codes will probably no longer be secure in the future.<header><h2>Encryption by means of physical laws</h2></header>Tobias Vogl, a&nbsp;<a href="https://www.ce.cit.tum.de/qcs/home/" target="_blank" rel="noreferrer">professor of Quantum Communication Systems Engineering</a>, is working on an encryption process that relies on principles of physics. “Security will be based on the information being encoded into individual light particles and then transmitted. The laws of physics do not permit this information to be extracted or copied. When the information is intercepted, the light particles change their characteristics. Because we can measure these state changes, any attempt to intercept the transmitted data will be recognized immediately, regardless of future advances in technology,” says Tobias Vogl.The big challenge in so-called quantum cryptography lies in the transmission of data over long distances. In classical communications, information is encoded in many light particles and transmitted through optical fibers. However, the information in a single particle cannot be copied. As a result, the light signal cannot be repeatedly amplified, as with current optical fiber transmissions. This limits the transmission distance for the information to a few hundred kilometers.To send information to other cities or continents, the structure of the atmosphere will be used. At altitudes higher than around 10 kilometers, the atmosphere is so thin that light is neither scattered nor absorbed. This will make it possible to use satellites in order to extend quantum communications over longer distances.<header><h2>Satellites for quantum communications</h2></header>As part of the QUICK³ mission, Tobias Vogl and his team are developing an entire system, including all of the components needed to build a satellite for quantum communications. In a first step, the team tested each of the satellite components. The next step will be to try out the entire system in space. The researchers will investigate whether the technology can withstand outer space conditions and how the individual system components interact. The satellite launch is scheduled for 2025. To create an overarching network for quantum communications, however, hundreds or perhaps thousands of satellites will be needed.<header><h2>Hybrid network for encryption</h2></header>The concept does not necessarily require all information to be transmitted using this method, which is highly complex and costly. It is conceivable that a hybrid network could be implemented in which data can be encrypted either physically or mathematically. Antonia Wachter-Zeh, a <a href="https://www.ce.cit.tum.de/en/lnt/people/professors/wachter-zeh/" target="_blank" rel="noreferrer">professor of Coding and Cryptography</a>, is working to <a href="https://www.tum.de/en/news-and-events/all-news/press-releases/details/quantum-safe-data-encryption" target="_blank">develop algorithms sufficiently complex that not even quantum computers</a> can solve them. In the future it will still be enough to encrypt most information using mathematical algorithms. Quantum cryptography will be an option only for documents requiring special protection, for example in communications between banks.<hr>Najme Ahmadi, Sven Schwertfeger, Philipp Werner, Lukas Wiese, Joseph Lester, Elisa Da Ros, Josefine Krause, Sebastian Ritter, Mostafa Abasifard, Chanaprom Cholsuk, Ria G. Krämer, Simone Atzeni, Mustafa Gündoğan, Subash Sachidananda, Daniel Pardo, Stefan Nolte, Alexander Lohrmann, Alexander Ling, Julian Bartholomäus, Giacomo Corrielli, Markus Krutzik, Tobias Vogl. "QUICK3 - Design of a Satellite-Based Quantum Light Source for Quantum Communication and Extended Physical Theory Tests in Space“. Adv. Quantum Technol. (2024).&nbsp;<a href="https://doi.org/10.1002/qute.202300343" target="_blank" rel="noreferrer" id="isPasted">doi.org/10.1002/qute.202300343</a>

Tobias Vogl investigates single photon sources in 2D materials in an experimental setup

Through steady advances in the development of quantum computers and their ever-improving performance, it will be possible in the future to crack our current encryption processes.

Satellites for quantum communications

In diamonds (and other semiconducting materials), defects are a quantum sensor’s best friend.That’s because defects, essentially a jostled arrangement of atoms, sometimes contain electrons with an angular momentum, or spin, that can store and process information. This “spin degree of freedom” can be harnessed for a range of purposes, such as sensing magnetic fields or making a quantum network.Researchers led by&nbsp;<a href="http://fuchs.research.engineering.cornell.edu/fuchs" target="_blank">Greg Fuchs</a>, Ph.D. ’07, professor of applied and engineering physics in Cornell Engineering, went searching for such a spin in the popular semiconductor gallium nitride and found it, surprisingly, in two distinct species of defect, one of which can be manipulated for future quantum applications.The group’s paper, “<a href="https://www.nature.com/articles/s41563-024-01803-5" target="_blank">Room Temperature Optically Detected Magnetic Resonance of Single Spins in GaN</a>,” published Feb. 12 in Nature Materials. The lead author is doctoral student Jialun Luo.Defects are what give gems their color, and for this reason they are also known as color centers. Pink diamonds, for example, get their hue from defects called nitrogen vacancy centers. However, there are many color centers that have yet to be identified, even in materials that are commonly used.“Gallium nitride, unlike diamond, is a mature semiconductor. It has been developed for wide bandgap high-frequency electronics, and that’s been a very intense effort over many, many years,” Fuchs said. “You can go and buy a wafer of it, it’s in your computer charger, probably, or electric car. But in terms of a material for quantum defects, it has not been explored very much.”In order to search for the spin degree of freedom in gallium nitride, Fuchs and Luo teamed up with&nbsp;<a href="https://www.ece.cornell.edu/faculty-directory/farhan-rana" target="_blank">Farhan Rana</a>, the Joseph P. Ripley Professor of Engineering, and doctoral student Yifei Geng, with whom they had previously explored the material.The group used confocal microscopy to identify the defects via fluorescent probes and then conducted a host of experiments, such as measuring how a defect’s fluorescence rate changes as a function of magnetic field, and using a small magnetic field to drive the defect’s spin resonant transmissions, all at room temperature.“At the beginning, the preliminary data showed signs of interesting spin structures but we couldn’t drive the spin resonance,” Luo said. “It turns out that we needed to know the defect symmetry axes and apply a magnetic field along the correct direction to probe the resonances; the results brought us more questions, waiting to be worked out.”The experiments showed the material had two types of defects with a distinct spin spectra. In one, the spin was coupled to a metastable excited state; in the other, it was coupled to the ground state.In the latter case, the researchers were able to see fluorescence changes of up to 30% when they drove the spin transition – a large change in contrast, and relatively rare, for a quantum spin at room temperature.“Usually the fluorescence and spin are tied together very weakly, so when you change the spin projection, the fluorescence might change by 0.1%, or something very, very tiny,” Fuchs said. “From a technology standpoint, that isn’t great, because you want a big change, so that you can measure it quickly and efficiently.”The researchers then performed a quantum control experiment. They found they could manipulate the ground-state spin and that it had quantum coherence – a quality that allows quantum bits, or qubits, to retain their information.“That’s something that is pretty exciting about this observation,” Fuchs said. “There’s still a lot of fundamental work to do, and there’s many more questions than there are answers. But the basic discovery of spin in this color center, the fact that it has a strong spin contrast up to 30%, that it exists in a mature semiconductor material – that opens up all kinds of interesting possibilities that we now are excited to explore.”The research was supported by the <a href="http://www.ccmr.cornell.edu/" target="_blank">Cornell Center for Materials Research</a> (CCMR), with funding from the National Science Foundation’s Materials Research Science and Engineering Center program; the Cornell Engineering Sprout program; and the NSF’s Quantum Sensing Challenges for Transformational Advances in Quantum Systems program.The researchers made use of the&nbsp;<a href="https://www.cnf.cornell.edu/" target="_blank">Cornell NanoScale Facility</a>, also supported by the NSF.

Doctoral student Jialun Luo (left) and Greg Fuchs, Ph.D. ’07, professor of applied and engineering physics in Cornell Engineering, searched for a “spin degree of freedom” in the popular semiconductor gallium nitride and found it, surprisingly, in two distinct species of defect. Credits: Charissa King-O’Brien/Cornell Engineering

In diamonds (and other semiconducting materials), defects are a quantum sensor’s best friend.

Semiconductor defects could boost quantum technology

An international team that includes Rutgers University–New Brunswick scientists has developed a new method to make and manipulate a widely studied class of high-temperature superconductors.This technique should pave the way for the creation of unusual forms of superconductivity in previously unattainable materials.When cooled to a critical temperature, superconductors can conduct electricity without resistance or energy loss. These materials have intrigued physicists for decades because they can achieve a state of perfect conductivity allowing an electric current to flow indefinitely. But most superconductors only exhibit this peculiarity at temperatures so low – a few degrees above absolute zero – which renders them impractical.The new work,&nbsp;<a href="https://www.science.org/doi/abs/10.1126/science.abl8371?af=R" target="_blank">published</a>&nbsp;in Science, describes experiments that grew out of theoretical calculations that included those by a Rutgers team led by&nbsp;<a href="https://sites.rutgers.edu/pixley-group/people/jed-pixley/" target="_blank">Jedediah Pixley</a>, an associate professor in the Department of Physics and Astronomy in the Rutgers School of Arts and Sciences.The experiments confirmed predictions by Pixley and Pavel Volkov, who at the time was a postdoctoral fellow at the Rutgers&nbsp;<a href="https://cmt.rutgers.edu/" target="_blank">Center for Materials Theory</a>. These predictions, based on mathematical models Pixley and Volkov (now at the University of Connecticut) devised to represent the underlying quantum physical behavior,&nbsp;projected&nbsp;how cuprate superconductors would behave if they were placed in proximity in specific configurations and at varying angles.Superconductors are already in use today. Since the 1970s, scientists have employed superconducting magnets to generate the powerful magnetic fields needed for the operation of magnetic resonance imaging (MRI) machines. Maglev trains using the technology were introduced in the 1980s. More recently, scientists have harnessed the power of superconducting magnets to guide electron beams in experimental devices such as synchrotrons and accelerators.In the future, scientists envision a world where ultra-efficient electricity grids, ultrafast and energy-efficient computer chips, and even quantum computers are powered by new kinds of superconducting materials.The new experiments that validated Pixley and Volkov’s ideas were conducted by a team at Harvard University led by professor and physicist Philip Kim.“We took two cuprate superconductors – materials that already were interesting – and, in placing them together and twisting them in a precise way, made something else that was very interesting: another superconductor which could have lots of technological applications,” said Pixley, a condensed matter theorist.Because of its unique properties, the new superconductor is a promising candidate for the world’s first high-temperature,&nbsp;superconducting diode, essentially a switch that controls the flow of electrical current, the researchers said.Such a device could potentially fuel fledgling industries such as quantum computing, which rely on fleeting phenomena produced in materials like superconductors, they added.Pixley, who joined the Rutgers faculty in 2017, earned his doctoral degree by studying the conditions involved in producing superconductivity in unconventional materials. The latest research extends the field of “twistronics,” which involves twisting flat layers of two-dimensional materials to produce physical effects at the subatomic level that are observable on the macroscopic scale.To Pixley, the study enlarges the paradigm of what materials can exhibit superconducting properties when twisted. The work yields other insights, as well.“At the same time, we have found that this leads to a novel type of ‘magnetic’ superconducting state that has been long sought after, showing definitively that different superconducting phases can be reached via a twist," he said.The experimentalists first split an extremely thin film of a superconductive cuprate – nicknamed “BSCCO” and made of bismuth strontium calcium copper oxide – into two layers. Then, maintaining frigid conditions, they stacked the layers at a 45-degree twist, like an ice cream sandwich with askew wafers, retaining superconductivity at the fragile interface.Cuprates are copper oxides that, decades ago, upended the physics world by showing they become superconducting at much higher temperatures than theorists had thought possible. BSCCO is considered a high-temperature superconductor because it starts superconducting at about -288 Fahrenheit. That is very cold by practical standards, but astonishingly high among classical superconductors, which typically must be cooled to about -400 Fahrenheit.The work opens the door to more experiments, Pixley said.“It will be very exciting to extend these experiments to other configurations of superconductors – twisted monolayers and a few twisted multilayers of superconductors at small twist angles,” Pixley said.Other researchers on the study included scientists from the University of British Columbia, Brookhaven National Laboratory, the Leibniz Institute for Solid State and Materials Research in Germany, Seoul National University in South Korea and the National Institute for Materials Science in Japan.

Rutgers theorists have helped pave the way for the creation of superconductivity in previously unattainable materials.

Theory becomes reality when Rutgers–New Brunswick scientists help develop process for twisting materials in ways never thought possible

Researchers Craft New Way to Make High-Temperature Superconductors - With a Twist

Researchers at the Georgia Institute of Technology have created the world’s first functional semiconductor made from graphene, a single sheet of carbon atoms held together by the strongest bonds known. Semiconductors, which are materials that conduct electricity under specific conditions, are foundational components of electronic devices. The team’s breakthrough throws open the door to a new way of doing electronics.Their <a href="https://www.youtube.com/watch?v=gWUX2OTqkEo" target="_blank">discovery</a> comes at a time when silicon, the material from which nearly all modern electronics are made, is reaching its limit in the face of increasingly faster computing and smaller electronic devices. <a href="https://physics.gatech.edu/user/walter-de-heer" target="_blank">Walter de Heer</a>, Regents’ Professor of <a href="https://physics.gatech.edu/" target="_blank">physics</a> at Georgia Tech, led a team of researchers based in Atlanta, Georgia, and Tianjin, China, to produce a graphene semiconductor that is compatible with conventional microelectronics processing methods — a necessity for any viable alternative to silicon.<iframe width="640" height="360" src="https://www.youtube.com/embed/gWUX2OTqkEo?&amp;wmode=opaque&amp;rel=0&amp;enablejsapi=1&amp;origin=https://www.wevolver.com" frameborder="0" allowfullscreen="" class="fr-draggable" data-lf-form-tracking-inspected-kn9eq4roawkarlvp="true" data-lf-yt-playback-inspected-kn9eq4roawkarlvp="true" data-lf-vimeo-playback-inspected-kn9eq4roawkarlvp="true"></iframe>In this latest research, <a href="https://www.nature.com/articles/s41586-023-06811-0" target="_blank" id="isPasted">published in Nature</a>, de Heer and his team overcame the paramount hurdle that has been plaguing graphene research for decades, and the reason why many thought graphene electronics would never work. Known as the "band gap", it is a crucial electronic property that allows semiconductors to switch on and off. Graphene didn't have a band gap – until now.&nbsp;"We now have an extremely robust graphene semiconductor with 10 times the mobility of silicon, and which also has unique properties not available in silicon," de Heer said. "But the story of our work for the past 10 years has been, 'Can we get this material to be good enough to work?'"&nbsp;<h2 id="isPasted">A New Type of Semiconductor</h2><img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1704463112860-furnace.jpg" style="width: 300px;" class="fr-fic fr-dib">De Heer started to explore carbon-based materials as potential semiconductors early in his career, and then made the switch to 2D graphene in 2001. He knew at that time that graphene had potential for electronics."We were motivated by the hope of introducing three special properties of graphene into electronics," he said. "It's an extremely robust material, one that can handle very large currents, and can do so without heating up and falling apart."<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1704463145678-disco-ball-2a.png" style="width: 300px;" class="fr-fic fr-dib">De Heer achieved a breakthrough when he and his team figured out how to grow graphene on silicon carbide wafers using special furnaces. They produced epitaxial graphene, which is a single layer that grows on a crystal face of the silicon carbide. The team found that when it was made properly, the epitaxial graphene chemically bonded to the silicon carbide and started to show semiconducting properties.Over the next decade, they persisted in perfecting the material at Georgia Tech and later in collaboration with colleagues at the Tianjin International Center for Nanoparticles and Nanosystems at Tianjin University in China. De Heer founded the center in 2014 with Lei Ma, the center’s director and a co-author of the paper.<h3>How They Did It</h3>In its natural form, graphene is neither a semiconductor nor a metal, but a semimetal. A band gap is a material that can be turned on and off when an electric field is applied to it, which is how all transistors and silicon electronics work. The major question in graphene electronics research was how to switch it on and off so it can work like silicon.But to make a functional transistor, a semiconducting material must be greatly manipulated, which can damage its properties. To prove that their platform could function as a viable semiconductor, the team needed to measure its electronic properties without damaging it.They put atoms on the graphene that "donate" electrons to the system — a technique called doping, used to see whether the material was a good conductor. It worked without damaging the material or its properties.&nbsp;<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1704463161937-notebook-working.jpg" style="width: 300px;" class="fr-fic fr-dib">The team's measurements showed that their graphene semiconductor has 10 times greater mobility than silicon. In other words, the electrons move with very low resistance, which, in electronics, translates to faster computing. "It's like driving on a gravel road versus driving on a freeway," de Heer said. "It's more efficient, it doesn't heat up as much, and it allows for higher speeds so that the electrons can move faster."The team’s product is currently the only two-dimensional semiconductor that has all the necessary properties to be used in nanoelectronics, and its electrical properties are far superior to any other 2D semiconductors currently in development.&nbsp;"A long-standing problem in graphene electronics is that graphene didn’t have the right band gap and couldn’t switch on and off at the correct ratio,” said Ma. “Over the years, many have tried to address this with a variety of methods. Our technology achieves the band gap, and is a crucial step in realizing graphene-based electronics."<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1704463180843-silicon.jpg" style="width: 300px;" class="fr-fic fr-dib"><h3 id="isPasted">Moving Forward<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1704463198199-graphene-bottle.jpg" style="width: 300px;" class="fr-fic fr-dib"> </h3>Epitaxial graphene could cause a paradigm shift in the field of electronics and allow for completely new technologies that take advantage of its unique properties. The material allows the quantum mechanical wave properties of electrons to be utilized, which is a requirement for quantum computing."Our motivation for doing graphene electronics has been there for a long time, and the rest was just making it happen," de Heer said. "We had to learn how to treat the material, how to make it better and better, and finally how to measure the properties. That took a very, very long time."<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1704463217513-chip-in-box_0.jpg" style="width: 300px;" class="fr-fic fr-dib">According to de Heer, it is not unusual to see yet another generation of electronics on its way. Before silicon, there were vacuum tubes, and before that, there were wires and telegraphs. Silicon is one of many steps in the history of electronics, and the next step could be graphene."To me, this is like a Wright brothers moment," de Heer said. "They built a plane that could fly 300 feet through the air. But the skeptics asked why the world would need flight when it already had fast trains and boats. But they persisted, and it was the beginning of a technology that can take people across oceans."<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1704463293235-ezgif-4-c7538c2cac.jpg" style="width: 300px;" class="fr-fic fr-dib"><hr>Citation: Zhao, J.&nbsp;et al. Ultrahigh-mobility semiconducting epitaxial graphene on silicon carbide.&nbsp;Nature (2024).DOI: <a href="https://doi.org/10.1038/s41586-023-06811-0" target="_blank">https://doi.org/10.1038/s41586-023-06811-0</a>Video and Photos: Chris McKenney

The technology could allow for smaller and faster electronic devices and may have applications for quantum computing.

Researchers Create First Functional Semiconductor Made From Graphene

The practice of keeping time hinges on stable oscillations. In a grandfather clock, the length of a second is marked by a single swing of the pendulum. In a digital watch, the vibrations of a quartz crystal mark much smaller fractions of time. And in atomic clocks, the world’s state-of-the-art timekeepers, the oscillations of a laser beam stimulate atoms to vibrate at 9.2 billion times per second. These smallest, most stable divisions of time set the timing for today’s satellite communications, GPS systems, and financial markets.A clock’s stability depends on the noise in its environment. A slight wind can throw a pendulum’s swing out of sync. And heat can disrupt the oscillations of atoms in an atomic clock. Eliminating such environmental effects can improve a clock’s precision. But only by so much.A new MIT study finds that even if all noise from the outside world is eliminated, the stability of clocks, laser beams, and other oscillators would still be vulnerable to quantum mechanical effects. The precision of oscillators would ultimately be limited by quantum noise.But in theory, there’s a way to push past this quantum limit. In their study, the researchers also show that by manipulating, or “squeezing,” the states that contribute to quantum noise, the stability of an oscillator could be improved, even past its quantum limit.“What we’ve shown is, there’s actually a limit to how stable oscillators like lasers and clocks can be, that’s set not just by their environment, but by the fact that quantum mechanics forces them to shake around a little bit,” says Vivishek Sudhir, assistant professor of mechanical engineering at MIT. “Then, we’ve shown that there are ways you can even get around this quantum mechanical shaking. But you have to be more clever than just isolating the thing from its environment. You have to play with the quantum states themselves.”The team is working on an experimental test of their theory. If they can demonstrate that they can manipulate the quantum states in an oscillating system, the researchers envision that clocks, lasers, and other oscillators could be tuned to super-quantum precision. These systems could then be used to track infinitesimally small differences in time, such as the fluctuations of a single qubit in a quantum computer or the presence of a dark matter particle flitting between detectors.“We plan to demonstrate several instances of lasers with quantum-enhanced timekeeping ability over the next several years,” says Hudson Loughlin, a graduate student in MIT’s Department of Physics. “We hope that our recent theoretical developments and upcoming experiments will advance our fundamental ability to keep time accurately, and enable new revolutionary technologies.”Loughlin and Sudhir detail their work in an open-access&nbsp;<a href="https://www.nature.com/articles/s41467-023-42739-9" target="_blank">paper published in the journal&nbsp;Nature Communications</a>.<h2>Laser precision</h2>In studying the stability of oscillators, the researchers looked first to the laser — an optical oscillator that produces a wave-like beam of highly synchronized photons. The invention of the laser is largely credited to physicists Arthur Schawlow and Charles Townes, who coined the name from its descriptive acronym: light amplification by stimulated emission of radiation.A laser’s design centers on a “lasing medium” — a collection of atoms, usually embedded in glass or crystals. In the earliest lasers, a flash tube surrounding the lasing medium would stimulate electrons in the atoms to jump up in energy. When the electrons relax back to lower energy, they give off some radiation in the form of a photon. Two mirrors, on either end of the lasing medium, reflect the emitted photon back into the atoms to stimulate more electrons, and produce more photons. One mirror, together with the lasing medium, acts as an “amplifier” to boost the production of photons, while the second mirror is partially transmissive and acts as a “coupler” to extract some photons out as a concentrated beam of laser light.Since the invention of the laser, Schawlow and Townes put forth a hypothesis that a laser’s stability should be limited by quantum noise. Others have since tested their hypothesis by modeling the microscopic features of a laser. Through very specific calculations, they showed that indeed, imperceptible, quantum interactions among the laser’s photons and atoms could limit the stability of their oscillations.“But this work had to do with extremely detailed, delicate calculations, such that the limit was understood, but only for a specific kind of laser,” Sudhir notes. “We wanted to enormously simplify this, to understand lasers and a wide range of oscillators."<h2>Putting the “squeeze” on</h2>Rather than focus on a laser’s physical intricacies, the team looked to simplify the problem.“When an electrical engineer thinks of making an oscillator, they take an amplifier, and they feed the output of the amplifier into its own input,” Sudhir explains. “It’s like a snake eating its own tail. It’s an extremely liberating way of thinking. You don’t need to know the nitty gritty of a laser. Instead, you have an abstract picture, not just of a laser, but of all oscillators.”In their study, the team drew up a simplified representation of a laser-like oscillator. Their model consists of an amplifier (such as a laser’s atoms), a delay line (for instance, the time it takes light to travel between a laser’s mirrors), and a coupler (such as a partially reflective mirror).The team then wrote down the equations of physics that describe the system’s behavior, and carried out calculations to see where in the system quantum noise would arise.“By abstracting this problem to a simple oscillator, we can pinpoint where quantum fluctuations come into the system, and they come in in two places: the amplifier and the coupler that allows us to get a signal out of the oscillator,” Loughlin says. “If we know those two things, we know what the quantum limit on that oscillator’s stability is.”Sudhir says scientists can use the equations they lay out in their study to calculate the quantum limit in their own oscillators.What’s more, the team showed that this quantum limit might be overcome, if quantum noise in one of the two sources could be “squeezed.” Quantum squeezing is the idea of minimizing quantum fluctuations in one aspect of a system at the expense of proportionally increasing fluctuations in another aspect. The effect is similar to squeezing air from one part of a balloon into another.In the case of a laser, the team found that if quantum fluctuations in the coupler were squeezed, it could improve the precision, or the timing of oscillations, in the outgoing laser beam, even as noise in the laser’s power would increase as a result.“When you find some quantum mechanical limit, there’s always some question of how malleable is that limit?” Sudhir says. “Is it really a hard stop, or is there still some juice you can extract by manipulating some quantum mechanics? In this case, we find that there is, which is a result that is applicable to a huge class of oscillators.”

Clocks, lasers, and other oscillators could be tuned to super-quantum precision, allowing researchers to track infinitesimally small differences in time, according to a new MIT study. Image: MIT News; iStock

More stable clocks could measure quantum phenomena, including the presence of dark matter.

With a quantum "squeeze," clocks could keep even more precise time, MIT researchers propose

Acoustic resonators are everywhere. In fact, there is a good chance you’re holding one in your hand right now. Most smart phones today use bulk acoustic resonators as radio frequency filters to filter out noise that could degrade a signal. These filters are also used in most Wi-Fi and GPS systems.&nbsp;Acoustic resonators are more stable than their electrical counterparts, but they can degrade over time. There is currently no easy way to actively monitor and analyze the degradation of the material quality of these widely used devices.Now, researchers at the <a href="https://seas.harvard.edu/" target="_blank">Harvard John A. Paulson School of Engineering and Applied Sciences</a> (SEAS), in collaboration with researchers at the OxideMEMS Lab at Purdue University, have developed a system that uses atomic vacancies in silicon carbide to measure the stability and quality of acoustic resonators. What’s more, these vacancies could also be used for acoustically-controlled quantum information processing, providing a new way to manipulate quantum states embedded in this commonly-used material.&nbsp;“Silicon carbide, which is the host for both the quantum reporters and the acoustic resonator probe, is a readily available commercial semiconductor that can be used at room temperature,” said <a href="https://seas.harvard.edu/person/evelyn-hu" target="_blank">Evelyn Hu</a>, the Tarr-Coyne Professor of Applied Physics and of Electrical Engineering and the Robin Li and Melissa Ma Professor of Arts and Sciences, and a &nbsp;senior author of the paper. “As an acoustic resonator probe, this technique in silicon carbide could be used in monitoring the performance of accelerometers, gyroscopes and clocks over their lifetime and, in a quantum scheme, has potential for hybrid quantum memories and quantum networking.”&nbsp;The research was published in <a href="https://www.nature.com/articles/s41928-023-01029-4" target="_blank">Nature Electronics</a>.&nbsp;<h2>A look inside acoustic resonators&nbsp;</h2>Silicon carbide is a common material for microelectromechanical systems (MEMS), which includes bulk acoustic resonators.&nbsp;“Wafer-scale manufacturable silicon carbide resonators in particular are known to have the best-in-class performance for quality factor,” said Sunil Bhave,&nbsp;professor at the Elmore Family School of Electrical and Computer Engineering at Purdue and co-author of the paper. &nbsp;“But crystal growth defects such as dislocations and grain boundaries as well as resonator manufacturing defects such as roughness, tether stress, and micro-scale craters can cause stress-concentrations regions inside the MEMS resonator.”Today, the only way to see what’s happening inside an acoustic resonator without destroying it is with super powerful and very expensive x-rays, such as the broad-spectral x-ray beam at the Argonne National Lab.&nbsp;“These types of expensive and difficult-to-access machines are not deployable for doing measurements or characterization in a foundry or somewhere where you’d actually be making or deploying these devices,” said Jonathan Dietz, graduate student at SEAS and co-first author of the paper. “Our motivation was to try to develop an approach that would allow us to monitor the acoustic energy inside of a bulk acoustic resonator so you can then take those results and feed them back into the design and fabrication process.”<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1698480897314-41928_2023_1029_Fig1_HTML.jpeg" style="width: 766px;" class="fr-fic fr-dib">A piezoelectric layer (green) sandwiched between two electrodes (yellow) atop of a silicon carbide acoustic resonator (blue). Acoustic waves generated by the electrodes and piezoelectric layer put mechanical strain on the lattice, which flip the spin of the defect (red). The spin is read out with a laser focused onto the backside of the resonator. (Credit: Hu Group/Harvard SEAS)Silicon carbide commonly hosts naturally occurring defects in which an atom is removed from the crystal lattice, creating a spatially local electronic state whose spin can interact with sound waves through material strain, such as the strain generated by an acoustic resonator.&nbsp;When acoustic waves move through the material, they put mechanical strain on the lattice, which can flip the spin of the defect. Changes in the spin state can be observed by shining a laser through the material to see how many defects are “on” or “off” after perturbing them.&nbsp;“How dim or how bright the light indicates how strong the acoustic energy is in the local environment where the defect is,” said Aaron Day, a graduate student at SEAS and co-author of the paper. &nbsp;“Because these defects are the size of single atoms, the information they give you is very local and, as a result, you can actually map out the acoustic waves inside the device in this non-destructive way.”&nbsp;That map can point to where and how the system may be degrading or not operating optimally.&nbsp;<h3>Acoustic control&nbsp;</h3>Those same defects in silicon carbide can also be qubits within a quantum system.&nbsp;Today, many quantum technologies build on the coherence of spins: how long spins will remain in a particular state. &nbsp;That coherence is often controlled with a magnetic field.&nbsp;But with their technique, Hu and her team demonstrated that they could control spin by mechanically deforming the material with acoustic waves, obtaining a quality of control similar to other approaches using alternating magnetic fields.&nbsp;“To use the natural mechanical properties of a material — its strain — expands the range of material control that we have,” said Hu. “When we deform the material, we find that we can also control the coherence of spin and we can get that information just by launching an acoustic wave through the material. It provides an important new handle on an intrinsic property of a material that we can use to control the quantum state embedded within that material.”The research was co-authored by Boyang Jiang. It was supported by the National Science Foundation under the RAISE-TAQS Award 1839164 and grant DMR-1231319.&nbsp;

Control of atomic vacancies with sound waves could improve communications and offer new control for quantum computing

Using sound to test devices, control qubits

Ordinary pencil lead holds extraordinary properties when shaved down to layers as thin as an atom. A single, atom-thin sheet of graphite, known as graphene, is just a tiny fraction of the width of a human hair. Under a microscope, the material resembles a chicken-wire of carbon atoms linked in a hexagonal lattice.Despite its waif-like proportions, scientists have found over the years that graphene is exceptionally strong. And when the material is stacked and twisted in specific contortions, it can take on surprising electronic behavior.Now, MIT physicists have discovered another surprising property in graphene: When stacked in five layers, in a rhombohedral pattern, graphene takes on a very rare, “multiferroic” state, in which the material exhibits both unconventional magnetism and an exotic type of electronic behavior, which the team has coined ferro-valleytricity.“Graphene is a fascinating material,” says team leader Long Ju, assistant professor of physics at MIT. “Every layer you add gives you essentially a new material. And now this is the first time we see ferro-valleytricity, and unconventional magnetism, in five layers of graphene. But we don’t see this property in one, two, three, or four layers.”The discovery could help engineers design ultra-low-power, high-capacity data storage devices for classical and quantum computers.“Having multiferroic properties in one material means that, if it could save energy and time to write a magnetic hard drive, you could also store double the amount of information compared to conventional devices,” Ju says.His team&nbsp;<a href="https://dspace.mit.edu/handle/1721.1/152434" target="_blank">reports their discovery</a> today in&nbsp;Nature. MIT co-authors include lead author Tonghang Han, plus Zhengguang Lu, Tianyi Han, and Liang Fu; along with Harvard University collaborators Giovanni Scuri, Jiho Sung, Jue Wang, and Hongkun Park; and Kenji Watanabe and Takashi Taniguchi of the National Institute for Materials Science in Japan.<h2>A preference for order</h2>A ferroic material is one that displays some coordinated behavior in its electric, magnetic, or structural properties. A magnet is a common example of a ferroic material: Its electrons can coordinate to spin in the same direction without an external magnetic field. As a result, the magnet points to a preferred direction in space, spontaneously.Other materials can be ferroic through different means. But only a handful have been found to be multiferroic — a rare state in which multiple properties can coordinate to exhibit multiple preferred states. In conventional multiferroics, it would be as if, in addition to the magnet pointing toward one direction, the electric charge also shifts in a direction that is independent from the magnetic direction. &nbsp;Multiferroic materials are of interest for electronics because they could potentially increase the speed and lower the energy cost of hard drives. Magnetic hard drives store data in the form of magnetic domains — essentially, microscopic magnets that are read as either a 1 or a 0, depending on their magnetic orientation. The magnets are switched by an electric current, which consumes a lot of energy and cannot operate quickly. If a storage device could be made with multiferroic materials, the domains could be switched by a faster, much lower-power electric field. Ju and his colleagues were curious about whether multiferroic behavior would emerge in graphene. The material’s extremely thin structure is a unique environment in which researchers have discovered otherwise hidden, quantum interactions. In particular, Ju wondered whether graphene would display multiferroic, coordinated behavior among its electrons when arranged under certain conditions and configurations.“We are looking for environments where electrons are slowed down — where their interactions with the surrounding lattice of atoms is small, so that their interactions with other electrons can come through,” Ju explains. “That’s when we have some chance of seeing interesting collective behaviors of electrons.”The team carried out some simple calculations and found that some coordinated behavior among electrons should emerge in a structure of five graphene layers stacked together in a rhombohedral pattern. (Think of five chicken-wire fences, stacked and slightly shifted such that, viewed from the top, the structure would resemble a pattern of diamonds.)“In five layers, electrons happen to be in a lattice environment where they move very slowly, so they can interact with other electrons effectively,” Ju says. “That’s when electron correlation effects start to dominate, and they can start to coordinate into certain preferred, ferroic orders.”<h2>Magic flakes</h2>The researchers then went into the lab to see whether they could actually observe multiferroic behavior in five-layer graphene. In their experiments, they started with a small block of graphite, from which they carefully exfoliated individual flakes. They used optical techniques to examine each flake, looking specifically for five-layer flakes, arranged naturally in a rhombohedral pattern.“To some extent, nature does the magic,” said lead author and graduate student Han. “And we can look at all these flakes and tell which has five layers, in this rhombohedral stacking, which is what should give you this slowing-down effect in electrons.”The team isolated several five-layer flakes and studied them at temperatures just above absolute zero. In such ultracold conditions, all other effects, such as thermally induced disorders within graphene, should be dampened, allowing interactions between electrons, to emerge. The researchers measured electrons’ response to an electric field and a magnetic field, and found that indeed, two ferroic orders, or sets of coordinated behaviors, emerged.The first ferroic property was an unconventional magnetism: The electrons coordinated their orbital motion, like planets circling in the same direction. (In conventional magnets, electrons coordinate their “spin” — rotating in the same direction, while staying relatively fixed in space.)The second ferroic property had to do with graphene’s electronic “valley.” In every conductive material, there are certain energy levels that electrons can occupy. A valley represents the lowest energy state that an electron can naturally settle. As it turns out, there are two possible valleys in graphene. Normally, electrons have no preference for either valley and settle equally into both.But in five-layer graphene, the team found that the electrons began to coordinate, and preferred to settle in one valley over the other. This second coordinated behavior indicated a ferroic property that, combined with the electrons’ unconventional magnetism, gave the structure a rare, multiferroic state.“We knew something interesting would happen in this structure, but we didn’t know exactly what, until we tested it,” says co-first author Lu, a postdoc in Ju’s group. “It’s the first time we’ve seen a ferro-valleytronics, and also the first time we’ve seen a coexistence of ferro-valleytronics with unconventional ferro-magnet.”The team showed they could control both ferroic properties using an electric field. They envision that, if engineers can incorporate five-layer graphene or similar multiferroic materials into a memory chip, they could, in principle, use the same, low-power electric field to manipulate the material’s electrons in two ways rather than one, and effectively double the data that could be stored on a chip compared to conventional multiferroics. While that vision is far from practical realization, the team’s results break new ground in the search for better, more efficient electronic, magnetic and valleytronic devices.This research was done, in part, using the electron-beam lithography facility run by MIT.nano, and is funded, in part, by the National Science Foundation and the Sloan Foundation.

When stacked in five layers in a rhombohedral pattern, graphene takes on a rare “multiferroic” state, in which the material’s electrons (illustrated here as spheres) exhibit two preferred electronic states: an unconventional magnetism (represented as orbits around each electron), and “valley,” or a preference for one of two energy states (depicted in red versus blue). The results could help advance more powerful magnetic memory devices. Image: Sampson Wilcox, RLE

A newly discovered type of electronic behavior could help with packing more data into magnetic memory devices.

From a five-layer graphene sandwich, a rare electronic state emerges

This article originally appeared in <a href="https://engineering.princeton.edu/news/2023/10/11/illuminating-errors-creates-new-paradigm-quantum-computing" target="_blank" rel="noopener noreferrer">Princeton University</a> and has been republished with permission.<hr>Researchers have developed a method that can reveal the location of errors in quantum computers, making them up to ten times easier to correct. This will significantly accelerate progress towards large-scale quantum computers capable of tackling the world’s most challenging computational problems, the researchers said.Led by Princeton University’s <a href="https://ece.princeton.edu/people/jeff-thompson" target="_blank">Jeff Thompson</a>, the team demonstrated a way to identify when errors occur in quantum computers more easily than ever before. This is a new direction for research into quantum computing hardware, which more often seeks to simply lower the probability of an error occurring in the first place.A <a href="https://www.nature.com/articles/s41586-023-06438-1" target="_blank">paper</a> detailing the new approach was published in Nature on Oct. 11. Thompson’s collaborators include Shruti Puri at Yale University and Guido Pupillo at the University of Strasbourg.Physicists have been inventing new qubits – the core component of quantum computers – for nearly three decades, and steadily improving those qubits to be less fragile and less prone to error. But some errors are inevitable no matter how good qubits get. The central obstacle to the future development of quantum computers is being able to correct for these errors. However, to correct an error, you first have to figure out if an error occurred, and where it is in the data. And typically, the process of checking for errors introduces more errors, which have to be found again, and so on.Quantum computers’ ability to manage those inevitable errors has remained more or less stagnant over that long period, according to Thompson, associate professor of electrical and computer engineering. He realized there was an opportunity in biasing certain kinds of errors.“Not all errors are created equal,” he said.<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1697112488641-Thompson-erasure-for-web-02.jpg" style="width: 766px;" class="fr-fic fr-dib">At the heart of this quantum computer, lasers control the states of individual atoms, manipulating information based on the extremely subtle physics of those atoms’ energy levels. Photo by Frank WojciechowskiThompson’s lab works on a type of quantum computer based on neutral atoms. Inside the ultra-high vacuum chamber that defines the computer, qubits are stored in the spin of individual ytterbium atoms held in place by focused laser beams called optical tweezers. In this work, a team led by graduate student Shuo Ma used an array of 10 qubits to characterize the probability of errors occurring while first manipulating each qubit in isolation, then manipulating pairs of qubits together.They found error rates near the state of the art for a system of this kind: 0.1 percent per operation for single qubits and 2 percent per operation for pairs of qubits.<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1697112509360-Qbit-erasure-final-Illustration-2048x1152.jpg" style="width: 766px;" class="fr-fic fr-dib">A team led by Jeff Thompson, associate professor of electrical and computer engineering, pioneered an approach to more efficient error correction in quantum computers. (Illustration by Gabriele Meilikhov/Muza Productions)However, the main result of the study is not only the low error rates, but also a different way to characterize them without destroying the qubits. By using a different set of energy levels within the atom to store the qubit, compared to previous work, the researchers were able to monitor the qubits during the computation to detect the occurrence of errors in real time. This measurement causes the qubits with errors to emit a flash of light, while the qubits without errors remain dark and are unaffected.This process converts the errors into a type of error known as an erasure error. Erasure errors have been studied in the context of qubits made from photons, and have long been known to be simpler to correct than errors in unknown locations, Thompson said. However, this work is the first time the erasure-error model has been applied to matter-based qubits. It follows a <a href="https://www.nature.com/articles/s41467-022-32094-6" target="_blank">theoretical proposal</a> last year from Thompson, Puri and Shimon Kolkowitz of the University of California-Berkeley.In the demonstration, approximately 56 percent of one-qubit errors and 33 percent of two-qubit errors were detectable before the end of the experiment. Crucially, the act of checking for errors doesn’t cause significantly more errors: The researchers showed that checking increased the rate of errors by less than 0.001 percent. According to Thompson, the fraction of errors detected can be improved with additional engineering.The researchers believe that, with the new approach, close to 98 percent of all errors should be detectable with optimized protocols. This could reduce the computational costs of implementing error correction by an order of magnitude or more.Other groups have already started to adapt this new error detection architecture. Researchers at Amazon Web Services and a separate group at Yale have independently shown how this new paradigm can also improve systems using superconducting qubits.“We need advances in many different areas to enable useful, large-scale quantum computing. One of the challenges of systems engineering is that these advances that you come up with don’t always add up constructively. They can pull you in different directions,” Thompson said. “What’s nice about erasure conversion is that it can be used in many different qubits and computer architectures, so it can be deployed flexibly in combination with other developments.”Additional authors on the paper “High-fidelity gates with mid-circuit erasure conversion in a metastable neutral atom qubit” include Shuo Ma, Genyue Liu, Pai Peng, Bichen Zhang, and Alex P. Burgers, at Princeton; Sven Jandura at Strasbourg; and Jahan Claes at Yale. This work was supported in part by the Army Research Office, the Office of Naval Research, DARPA, the National Science Foundation and the Sloan Foundation.

Researchers led by Jeff Thompson at Princeton University have developed a technique to make it 10 times easier to correct errors in a quantum computer. Photos by Frank Wojciechowski

Researchers have developed a method that can reveal the location of errors in quantum computers, making them up to ten times easier to correct. This will significantly accelerate progress towards large-scale quantum computers capable of tackling the world’s most challenging computational problems, the researchers said.

Illuminating errors creates a new paradigm for quantum computing

You may be one of those waiting for the quantum computer, the arrival of which we have been told is imminent for several years. Already at this point, DTU Associate Professor Sven Karlsson begins to look a little strained, because among his partners are the two European companies AQT and IQM which produce and sell quantum computers.&ldquo;It&rsquo;s a common misconception that the quantum computer doesn&rsquo;t exist yet. It does already exist, so it&rsquo;s not something we need to wait for. However, the current quantum computers aren&rsquo;t yet all that large, which obviously limits how complicated the calculations can be, but they exist and are being used,&rdquo; says Sven Karlsson.One example is IBM&rsquo;s quantum computers, which anyone can access via the internet. In addition, there are quantum computers in scientific laboratories, in supercomputer centres, at universities, and so on&mdash;worldwide. These are also among the customers to which AQT and IQM sell their products.<h2>Mostly for experiments</h2>It has not yet been possible to build quantum computers with many quantum bits. Quantum bits are used to process the information in the computer, and a low number of quantum bits therefore limits the complexity of the calculations the quantum computer can perform. Sven Karlsson therefore characterizes the current use as primarily experimental, making it possible to play with and understand the technology.&ldquo;The technical level of the current quantum computers is somewhat similar to the first stage of our current computers. When they first appeared in the 1950s, there were only a limited number of them, and, back then, they couldn&rsquo;t make larger calculations than those any calculator can perform today.&rdquo;However, there are examples of calculations performed using a quantum computer. One of the calculations known to Sven Karlsson was done during the coronavirus pandemic. The Italian football league needed to know how best to schedule the matches so that the different football teams came into contact with each other as little as possible to reduce the risk of infection. Likewise, travel distances for the players had to be limited, as travel by air was banned.&ldquo;A quantum computer is well suited for calculations of this type that will take too long for an ordinary supercomputer. The quantum computer can examine many solutions simultaneously and is therefore more efficient at such calculations than a supercomputer,&rdquo; says Sven Karlsson.<h2>Connects to supercomputers</h2>Sven Karlsson and his colleagues&rsquo; collaboration with AQT and IQM includes developing the hardware and software needed to connect the quantum computer to supercomputers.&ldquo;The future quantum computers will initially largely be connected to the relatively few high-performance computing centres with supercomputers that exist worldwide. The centres have already built an infrastructure with the right competences to operate the quantum computers, and it also makes sense to invest in relation to the existing centres. Today, a quantum computer costs around DKK 150 million, so it&rsquo;s a relatively large investment,&rdquo; says Sven Karlsson.The quantum computer will not replace supercomputers. Instead, it will supplement them and be used for highly specific calculations. Nor will the quantum computer have its own user interface, but must be accessed via the supercomputers.<h2>Standardization</h2>As a result of the current budding production of quantum computers worldwide, large-scale standardization work is being initiated. It includes standards for all the hardware and software parts that make up a quantum computer. The hope is to prevent inexpediencies that we struggle with in other technological areas, such as only being able to use one charger type for our mobile phone.&ldquo;We would like to develop joint standards so that, throughout the world, we have the same understanding and use of the different components that make up a quantum computer. This must be done already at this early stage, so that we don&rsquo;t risk individual countries or parts of the world introducing different standards,&rdquo; says Sven Karlsson.Sven Karlsson leads a group of researchers and practitioners with in-depth experience with and knowledge of quantum computers, who will meet in the coming years to create recognized standards that can be used in future production.

Quantum computers are being manufactured and used. But they cannot yet make the large-scale calculations that are expected to be possible in the future.

The quantum computer exists, but is not all that powerful

<a href="https://physics.cornell.edu/eun-ah-kim" target="_blank">Eun-Ah Kim</a>, professor of physics in the College of Arts and Sciences, and Google researchers report the first demonstration of two-dimensional particles, called non-Abelian anyons, that are the key ingredient for realizing topological quantum computing, a promising method of introducing fault resistance to quantum computing.&ldquo;<a href="https://www.nature.com/articles/s41586-023-05954-4" target="_blank">Non-Abelian Braiding of Graph Vertices in a Superconducting Processor</a>&rdquo; published May 11 in Nature. The experiment with Google Quantum AI, first posted to arXiv in October, is built on&nbsp;<a href="https://news.cornell.edu/stories/2023/04/physicists-take-step-toward-fault-tolerant-quantum-computing" target="_blank">the ground-breaking theory</a> also posted to arXiv in October and published in March by Kim and co-author Yuri Lensky, a former postdoctoral researcher in the&nbsp;<a href="https://www.lassp.cornell.edu/" target="_blank">Laboratory of Atomic and Solid State Physics</a>.Theorized about for 40 years but not realized in theory or experiment until 2022 by Kim and collaborators, non-Abelian anyons can, in certain 2D systems, produce a measurable record of their movement when two of them exchange positions. They retain a sort of memory, making it possible to tell when two of them have been exchanged, despite being completely identical.The resulting trail through space-time &ndash; known as a &ldquo;braid&rdquo; &ndash; could protect bits of quantum information by storing them nonlocally and could be used in a platform for protected quantum bits (qubits), Kim said.Google experimentalists used one of their superconducting quantum processors to observe the peculiar behavior of non-Abelian anyons for the first time and demonstrated how this phenomenon could be used to perform quantum computations. Error correction systems based on qubits will be necessary for quantum computing as the field develops.Following the protocol laid out in Kim and Lensky&rsquo;s theoretical work, Google Quantum AI experimentalists created and moved non-Abelian anyons physically on a 2D grid of qubits resembling a checkerboard. To realize non-Abelian anyons, they stretched and squashed the quantum state of qubits laid out on the grid, letting the qubits form more general graphs.Although backed by robust mathematics, Kim said, a simple geometric and creative insight is at the heart of both theory and experiment realizing non-Abelian anyons in the physical world.&ldquo;We needed to introduce a new theoretical framework relying on the mathematics of gauge theories,&rdquo; Kim said, &ldquo;to implement the edge-swinging moves on the device and predict quantum measurement outcomes.&ldquo;It looks simple, but the particles remember the history,&rdquo; Kim said. &ldquo;If you want this to be the technology of the future, you want it to be simple and straightforward.&rdquo;In a series of experiments, the Google researchers observed the behavior of these non-Abelian anyons and how they interacted with the more mundane particles in the setup. Weaving the two types of particles around each other led to bizarre phenomena; particles disappeared, reappeared and shapeshifted from one type to another, Google researchers said.Most importantly, the researchers observed the hallmark behavior of non-Abelian anyons researchers have been seeking for years: Swapping two of them caused a measurable change in the quantum state of their system. Finally, they demonstrated how braiding non-Abelian anyons might be used in quantum computations, creating a well-known quantum entangled state called the Greenberger-Horne-Zeilinger (GHZ) state by braiding several non-Abelian anyons together.Kim, co-chair of Cornell&rsquo;s&nbsp;<a href="https://provost.cornell.edu/academic-initiatives/radical-collaboration/quantum/" target="_blank">Quantum Science and Technology Radical Collaboration</a>&nbsp;initiative, called thiswork a major advance in both condensed matter physics and quantum information science.&ldquo;Our observations represent an important milestone in the study of topological systems, and present a new platform for exploring the rich physics of non-Abelian anyons,&rdquo; Kim said. &ldquo;Moreover, through the future inclusion of error correction, it opens a new path towards fault-tolerant quantum computing.&rdquo;

Researchers report the first demonstration of two-dimensional particles, called non-Abelian anyons, that are the key ingredient for realizing topological quantum computing, a promising method of introducing fault resistance to quantum computing.

Cornell, Google first to detect key to quantum computing future

<article id="isPasted"><a href="https://www.dlr.de/content/en/glossary/q/qubit.html" target="_blank" title='Link to glossary entry "Qubit"'>Qubits</a> are the processing units of <a href="https://www.dlr.de/content/en/glossary/q/quantum-computer.html" target="_blank" title='Link to glossary entry "Quantum computer"'>quantum computers</a>. They can be created in various different ways. One option is the creation of solid-state spin qubits in materials such as diamonds, in which qubits get stuck in defects that are specifically inserted into the structure of diamond crystals. The German Aerospace Center (Deutsches Zentrum f&uuml;r Luft- und Raumfahrt; DLR) has now awarded two contracts related to this activity as part of the <a href="https://qci.dlr.de/en/start/" target="_blank" title="External link DLR Quantum Computing Initiative (QCI)">DLR Quantum Computing Initiative (QCI)</a>. Over the next three and a half years, <a href="https://www.advanced-quantum.de/" target="_blank" title="External link Advanced Quantum GmbH">Advanced Quantum</a> from Allmersbach (Baden-W&uuml;rttemberg) will develop quality assurance procedures to accompany the creation of the modified diamond structures and other solid bodies that are suitable for qubits. <a href="https://diatope.com/" target="_blank" title="External link Diatope GmbH">Diatope</a> from Ummendorf (Baden-W&uuml;rttemberg) produces high-quality diamond layers with nitrogen-vacancy (NV) centres. The contracts amount to a total of 13 million euros.&quot;Start-ups benefit particularly from the DLR Quantum Computing Initiative; the young companies are effectively integrated into the development of a commercial ecosystem for quantum computing. This can lead to an industrial base that is internationally competitive and strengthens Germany as a technological location in this key technology,&quot; says Anna Christmann, Commissioner of the German Federal Ministry for Economic Affairs and Climate Action (<a href="https://www.bmwk.de/Navigation/EN/Home/home.html" target="_blank" title="External link Federal Ministry for Economic Affairs and Climate Action - BMWK">BMWK)</a> for the Digital Economy and Start-ups.&ldquo;Nitrogen-vacancy centres in diamond are considered particularly suitable spin qubits for use in the construction of quantum computers,&rdquo; says Robert Axmann, Head of the DLR Quantum Computing Initiative. &ldquo;To continue to make technological progress in this field, it is vital to have these spin qubits available in high quality and sufficient number. That is what these contracts aim to achieve.&rdquo; One of the advantages of diamond-based qubits is that they operate at room temperature. Superconducting systems, which are also solids, are comparatively well developed, but they require extremely low operating temperatures. &ldquo;For quantum computing, it is still unclear which systems scale well &ndash; in other words, allow for higher numbers of qubits &ndash; and eliminate or make it possible to correct errors. That makes it all the more important to investigate multiple qubit technologies,&rdquo; adds Axmann.<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1673658811696-red-fluorescence-of-a-diamond-with-nv-centres.jpg" style="width: 300px;" class="fr-fic fr-dib">Red flu&shy;o&shy;res&shy;cence from a di&shy;a&shy;mond with NV cen&shy;tres. Credit: &copy; Advanced Quantum GmbH&nbsp;<h2>Manufacturers reap mutual benefits</h2>The two start-ups support and accelerate the further development of quantum computers based on nitrogen-vacancy (NV) centres in diamond. They also ensure that the manufactured qubits have consistent properties. The awarded contracts will specifically develop and expand the ecosystem for the field of quantum computers based on solid-state spins and are closely interlinked with the contracts awarded for the <a href="https://www.dlr.de/content/en/articles/news/2022/04/20221212_how_diamonds_become_qubits.html" target="_blank" title="How diamonds become qubits">construction of quantum computers based on NV centres</a>.Advanced Quantum is working on quality assurance procedures for solid-state spin qubits. The defects in diamonds and other materials will be controlled with laser beams, microwaves and radio frequencies. In order to represent the properties of the spin qubits in as much detail as possible, Advanced Quantum also carries out an analysis of the samples at cryogenic (ultra-low) temperatures.Diatope produces quantum hardware based on NV centres. Diatope grows ultra-pure diamond layers in a controlled process and then implants nitrogen ions into the crystal structure. The diamonds are then heated. As a result, they regain their lattice structure, which was disrupted by the incorporation of the nitrogen ion. Diatope builds special systems to carry out these individual processes and then works to optimise their operation.&ldquo;These contracts have been awarded with close collaboration in mind, not just between the two projects, but also with other industry partners and DLR institutes involved in the DLR Quantum Computing Initiative. Everyone involved will benefit, and we will see advancements in the quantum computing ecosystem in Germany as a whole,&rdquo; says Karla Loida, Project Lead for the DLR Quantum Computing Initiative. Both start-ups will use laboratories at the DLR Innovation Centre in <a href="https://www.dlr.de/content/en/sites/ulm.html" target="_blank" title="Ulm">Ulm</a>. The Ulm site and the DLR Innovation Centre in <a href="https://www.dlr.de/content/en/sites/hamburg.html" target="_blank" title="Hamburg">Hamburg</a> offer synergies with local DLR institutes and other <a href="https://qci.dlr.de/en/start/" target="_blank" title="External link DLR Quantum Computing Initiative (QCI)">projects</a> involved in the DLR Quantum Computing Initiative.<h2>The DLR Quantum Computing Initiative</h2>The DLR Quantum Computing Initiative is overseeing the development of prototype quantum computers with different architectures over a period of four years. The associated technologies and applications are also being developed. DLR is bringing together established companies, start-ups and other research institutions in order to facilitate the development of significant technological advances.DLR has been granted funding by the Federal Ministry for Economic Affairs and Climate Action (BMWK), enabling it to award large-scale contracts to companies. DLR is contributing its own skills and research activities to the development and is focusing on technology transfer to industry.<h2>Rapid computations with quantum bits</h2>Quantum computers are an important technology for the future. They can perform calculations and simulations in specific fields of application much faster than conventional supercomputers. Their use is possible, for example, in the transport and energy sectors, but also in fundamental research or even in satellite operations. Quantum computers work on the basis of <a href="https://www.dlr.de/content/en/glossary/q/quantum-mechanics-quantum-physics.html" target="_blank" title='Link to glossary entry "Quantum mechanics / Quantum physics"'>quantum physics</a>. Their quantum bits (qubits) can not only assume the states 0 and 1, but also intermediate values, distinguishing then from conventional computers and allowing them to be so powerful. At DLR, several institutes are already working with quantum technologies. There is also a great need at DLR to conduct research on and with quantum computers in the future.</article>

Plas­ma ball in a growth re­ac­tor. Credit: © CO / Diatope GmbH

Qubits are the processing units of quantum computers. They can be created in various different ways. One option is the creation of solid-state spin qubits in materials such as diamonds, in which qubits get stuck in defects that are specifically inserted into the structure of diamond crystals.

Start-ups grow diamond qubits

This article was first published on&nbsp;<a href="https://news.mit.edu/2023/quantum-interconnects-photon-emission-0105" id="isPasted" rel="noopener noreferrer" target="_blank">MIT News</a>. &nbsp;<hr>Quantum computers hold the promise of performing certain tasks that are intractable even on the world&rsquo;s most powerful supercomputers. In the future, scientists anticipate using quantum computing to emulate materials systems, simulate quantum chemistry, and optimize hard tasks, with impacts potentially spanning finance to pharmaceuticals.However, realizing this promise requires resilient and extensible hardware. One challenge in building a large-scale&nbsp;<a href="https://news.mit.edu/2020/explained-quantum-engineering-1210" target="_blank">quantum computer</a> is that researchers must find an effective way to interconnect quantum information nodes &mdash; smaller-scale processing nodes separated across a computer chip. Because quantum computers are fundamentally different from classical computers, conventional techniques used to communicate electronic information do not directly translate to quantum devices. However, one requirement is certain: Whether via a classical or a quantum interconnect, the carried information must be transmitted and received.&nbsp; &nbsp;&nbsp;To this end, MIT researchers have developed a quantum computing architecture that will enable extensible, high-fidelity communication between superconducting quantum processors. In&nbsp;<a href="https://www.nature.com/articles/s41567-022-01869-5" target="_blank">work published today</a> in&nbsp;Nature Physics, MIT researchers demonstrate step one, the deterministic emission of single photons &mdash; information carriers &mdash; in a user-specified direction. Their method ensures quantum information flows in the correct direction more than 96 percent of the time.Linking several of these modules enables a larger network of quantum processors that are interconnected with one another, no matter their physical separation on a computer chip.&ldquo;Quantum interconnects are a crucial step toward modular implementations of larger-scale machines built from smaller individual components,&rdquo; says Bharath Kannan PhD &rsquo;22, co-lead author of a research paper describing this technique.&ldquo;The ability to communicate between smaller subsystems will enable a modular architecture for quantum processors, and this may be a simpler way of scaling to larger system sizes compared to the brute-force approach of using a single large and complicated chip,&rdquo; Kannan adds.Kannan wrote the paper with co-lead author Aziza Almanakly, an electrical engineering and computer science graduate student in the Engineering Quantum Systems group of the Research Laboratory of Electronics (RLE) at MIT. The senior author is William D. Oliver, an MIT professor of electrical engineering and computer science and of physics, an MIT Lincoln Laboratory Fellow, director of the Center for Quantum Engineering, and associate director of RLE.<h2>Moving quantum information</h2>In a conventional classical computer, various components perform different functions, such as memory, computation, etc. Electronic information, encoded and stored as bits (which take the value of 1s or 0s), is shuttled between these components using interconnects, which are wires that move electrons around on a computer processor.But quantum information is more complex. Instead of only holding a value of 0 or 1, quantum information can also be both 0 and 1 simultaneously (a phenomenon known as superposition). Also, quantum information can be carried by particles of light, called photons. These added complexities make quantum information fragile, and it can&rsquo;t be transported simply using conventional protocols.A quantum network links processing nodes using photons that travel through special interconnects known as waveguides. A waveguide can either be unidirectional, and move a photon only to the left or to the right, or it can be bidirectional.Most existing architectures use unidirectional waveguides, which are easier to implement since the direction in which photons travel is easily established. But since each waveguide only moves photons in one direction, more waveguides become necessary as the quantum network expands, which makes this approach difficult to scale. In addition, unidirectional waveguides usually incorporate additional components to enforce the directionality, which introduces communication errors.&ldquo;We can get rid of these lossy components if we have a waveguide that can support propagation in both the left and right directions, and a means to choose the direction at will. This &lsquo;directional transmission&rsquo; is what we demonstrated, and it is the first step toward bidirectional communication with much higher fidelities,&rdquo; says Kannan.Using their architecture, multiple processing modules can be strung along one waveguide. A remarkable feature the architecture design is that the same module can be used as both a transmitter and a receiver, he says. And photons can be sent and captured by any two modules along a common waveguide.&ldquo;We have just one physical connection that can have any number of modules along the way. This is what makes it scalable. Having demonstrated directional photon emission from one module, we are now working on capturing that photon downstream at a second module,&rdquo; Almanakly adds.<h2>Leveraging quantum properties</h2>To accomplish this, the researchers built a module comprising four qubits.Qubits are the building blocks of quantum computers, and are used to store and process quantum information. But qubits can also be used as photon emitters. Adding energy to a qubit causes the qubit to become excited, and then when it de-excites, the qubit will emit the energy in the form of a photon.However, simply connecting one qubit to a waveguide does not ensure directionality. A single qubit emits a photon, but whether it travels to the left or to the right is completely random. To circumvent this problem, the researchers utilize two qubits and a property known as quantum interference to ensure the emitted photon travels in the correct direction.The technique involves preparing the two qubits in an entangled state of single excitation called a Bell state. This quantum-mechanical state comprises two aspects: the left qubit being excited and the right qubit being excited. Both aspects exist simultaneously, but which qubit is excited at a given time is unknown.When the qubits are in this entangled Bell state, the photon is effectively emitted to the waveguide at the two qubit locations simultaneously, and these two &ldquo;emission paths&rdquo; interfere with each other. Depending on the relative phase within the Bell state, the resulting photon emission must travel to the left or to the right. By preparing the Bell state with the correct phase, the researchers choose the direction in which the photon travels through the waveguide.They can use this same technique, but in reverse, to receive the photon at another module.&ldquo;The photon has a certain frequency, a certain energy, and you can prepare a module to receive it by tuning it to the same frequency. If they are not at the same frequency, then the photon will just pass by. It&rsquo;s analogous to tuning a radio to a particular station. If we choose the right radio frequency, we&rsquo;ll pick up the music transmitted at that frequency,&rdquo; Almanakly says.The researchers found that their technique achieved more than 96 percent fidelity &mdash; this means that if they intended to emit a photon to the right, 96 percent of the time it went to the right.Now that they have used this technique to effectively emit photons in a specific direction, the researchers want to connect multiple modules and use the process to emit and absorb photons. This would be a major step toward the development of a modular architecture that combines many smaller-scale processors into one larger-scale, and more powerful, quantum processor.&ldquo;The work demonstrates an on-demand quantum emitter, in which the interference of the emitted photon from an entangled state defines the direction, beautifully manifesting the power of waveguide quantum electrodynamics,&rdquo; says Yasunobu Nakamura, director of the RIKEN Center for Quantum Computing, who was not involved with this research. &ldquo;It can be used as a fully programmable quantum node that can emit/absorb/pass/store quantum information on a quantum network and as an interface for a bus connecting multiple quantum computer chips.&rdquo;<hr>&quot;Reprinted with permission of&nbsp;<a href="https://news.mit.edu/2023/quantum-interconnects-photon-emission-0105" id="isPasted" rel="noopener noreferrer" target="_blank">MIT News</a>&quot; &nbsp;

This image shows a module composed of superconducting qubits that can be used to directionally emit microwave photons. Image: Krantz NanoArt

Researchers have demonstrated directional photon emission, the first step toward extensible quantum interconnects.

New quantum computing architecture could be used to connect large-scale devices

Quantum computers are considered the computers of the future.&nbsp;A and O are quantum bits (qubits), the smallest computing unit of quantum computers.&nbsp;Because they not only have two states, but also states in between, qubits process more information in less time.&nbsp;However, maintaining such a state for longer is difficult and depends in particular on the material properties.&nbsp;A KIT research team has now created qubits that are 100 times more sensitive to material defects - a crucial step in eradicating them.&nbsp;The team published the results in the journal&nbsp;Nature Materials (DOI:&nbsp;<a href="https://www.nature.com/articles/s41563-022-01417-9" target="_blank">10.1038/s41563-022-01417-9</a> ).Quantum computers can process large amounts of data faster because they carry out many calculation steps in parallel.&nbsp;The information carrier of the quantum computer is the qubit.&nbsp;With qubits, there is not only the information &ldquo;0&rdquo; and &ldquo;1&rdquo;, but also values in between.&nbsp;The difficulty at the moment, however, lies in making qubits that are small enough and can be switched fast enough to carry out quantum calculations.&nbsp;Superconducting circuits are considered a promising option here.&nbsp;Superconductors are materials that have no electrical resistance at extremely low temperatures and therefore conduct electricity without loss.&nbsp;This is crucial for preserving the quantum state of the qubits and connecting them together efficiently.&nbsp;<h2>Gralmonium Qubits: Superconducting and Sensitive</h2>KIT researchers have succeeded in developing novel and unconventional superconducting qubits.&nbsp;&ldquo;The heart of a superconducting qubit is a so-called Josephson junction, which is used to store quantum information.&nbsp;It is precisely at this point that we have made a decisive change,&quot; says Dr.&nbsp;Ioan M. Pop from the Institute for Quantum Materials and Technologies of KIT (IQMT).&nbsp;Typically, such Josephson junctions for superconducting quantum bits are created by separating two layers of aluminum with a thin oxide barrier.&nbsp;&quot;In contrast, for our qubits we only use a single layer of &#39;granular aluminum&#39;, a superconductor made of aluminum grains a few nanometers in size embedded in an oxide matrix,&quot; says Pop.&nbsp;As a result, the material itself forms a three-dimensional network of Josephson junctions.&nbsp;&quot;Excitingly, the entire properties of our qubit are dominated by a tiny constriction of only 20 nanometers.&nbsp;As a result, it acts like a magnifying glass for microscopic material defects in superconducting qubits and offers a promising perspective for their improvement,&quot; adds Simon G&uuml;nzler from IQMT.<h2>All of a piece: Qubits made entirely of granular aluminum</h2>The qubits developed by the team are a fundamental advancement of a previously tested approach with so-called fluxonium qubits.&nbsp;In this previous version, parts were made of granular aluminum and other parts were conventionally made of aluminum.&nbsp;In the current work, the researchers went the decisive step further and produced the complete qubits from granular aluminum.&nbsp;&quot;It&#39;s like simply cutting a quantum circuit out of a metal film.&nbsp;This results in completely new possibilities for industrial production with etching processes and expanded areas of application for the qubits, for example in strong magnetic fields,&quot; says Dennis Rieger from the Physics Institute of KIT.The authors also protected this invention with a European patent.<hr>Original publication D. Rieger, S. G&uuml;nzler, M. Spiecker, P. Paluch, P. Winkel, L. Hahn, JK Hohmann, A. Bacher, W. Wernsdorfer, and IM Pop: Granular Aluminum Nanojunction Fluxonium Qubit.&nbsp;Nature Materials, 2022. DOI: 10.1038/s41563-022-01417-9&nbsp;<a href="https://www.nature.com/articles/s41563-022-01417-9" target="_blank">https://www.nature.com/articles/s41563-022-01417-9</a>

The properties of Gralmonium qubits are dominated by a tiny constriction of just 20 nanometers, which acts like a magnifying glass for microscopic material defects. (Graphic: Dennis Rieger, KIT)

KIT researchers are working on a new qubit approach - publication in Nature Materials

More stable states for quantum computers

The time it takes medicines to move from discovery to approved use for patients can take decades and cost billions of dollars. Now, a $1.2 million National Science Foundation grant will help a team of Penn State researchers study the use of quantum computer-based artificial intelligence (AI) to see if quantum computers can bring drugs to patients faster and cheaper.Quantum computing differs from classical computers because quantum devices use quantum bits &mdash; or qubits &mdash; rather than classical bits. While bits can only be in binary positions of 1 and 0, qubits rely on the quantum mechanical principle of superposition that allow them to be in 1 and 0 positions simultaneously. Qubits can also be entangled, which means their states are intricately correlated. Theoretically, the devices&rsquo; computational potential increases exponentially for every qubit the scientists can entangle.According to&nbsp;<a href="https://www.eecs.psu.edu/departments/directory-detail-g.aspx?q=szg212" target="_blank">Swaroop Ghosh</a>, associate professor of electrical engineering and computer science and the grant&rsquo;s principal investigator, these strange &mdash; but scientifically proven &mdash; abilities give quantum computers the possibility of delivering exponentially more processing power to better handle certain complex problems.Ghosh added that using artificial intelligence (AI) models designed for quantum computers could be ideal for drug discovery, an area limited by current classical computing processing power.&ldquo;Quantum AI models are claimed to be more expressive compared to the classical neural networks -&mdash; in other words, they have higher capability to approximate a desired functionality compared to the classical AI models of similar scale,&rdquo; said Ghosh. &ldquo;Quantum computers bring effective sampling capabilities so they may be able to model useful distributions of drug-like molecules more efficiently than classical computers. Evolution of quantum primitives, such as quantum memory, can offer further speedup for machine learning tasks since the training data can be directly processed in the quantum domain.&rdquo;According to&nbsp;<a href="https://pennstate.pure.elsevier.com/en/persons/nikolay-dokholyan" target="_blank">Nikolay V. Dokholyan</a>, G. Thomas Passananti Professor, Penn State College of Medicine and co-principal investigator for the project, quantum computers could cut down on costs associated with finding drugs, as well as shorten the time it takes these needed treatments to reach patients.&ldquo;Drug discovery is a lengthy process that can span a decade and costs billions of dollars,&rdquo; said Dokholyan, who is also an associate of&nbsp;<a href="http://www.icds.psu.edu/" target="_blank">Penn State Institute for Computational and Data Science</a> (ICDS). &ldquo;Currently, the pace of Federal Drug Administration (FDA) approval of new compounds is only about 40 novel compounds per year. Accelerating drug discovery by computationally screening a massive number of compounds promises to significantly reduce the costs and time for finding effective new cures against diseases. &nbsp;Unlike the traditional computational drug screening approaches that target libraries of billions of compounds, utilizing Quantum Computers along with novel AI-driven algorithms promise to cover a vastly larger chemical space.&rdquo;Creating drugs quickly and cheaply means that lives will be saved, according to Ghosh.&ldquo;We lose millions of lives every year to diseases like cancer, for example, and the recent pandemic also indicated that we are ill-prepared to find effective drugs quickly,&rdquo; said Ghosh.The researchers are particularly interested in leveraging quantum AI to design drug treatments that could inhibit Ras family of proteins, which would be important for cancer treatments and cures.

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