Turning light particles into arithmetic building blocks offers great potential for building&nbsp;quantum computers. However, quantum processors based on light particles (photons) are less mature than other platforms. For the purpose of driving research and developing the potential of photonic systems, the German Aerospace Center (Deutsches Zentrum f&uuml;r Luft- und Raumfahrt; DLR) has awarded a contract worth 14 million euros to start-up&nbsp;<a href="https://www.quixquantum.com/" target="_blank" title="External link QuiX Quantum">QuiX Quantum</a>, which will develop prototype photonic quantum computers over the next four years. The contract has been awarded as part of the&nbsp;<a href="https://www.dlr.de/content/en/dossiers/2021/quantum-computing.html" target="_blank" title="Quantum computing">DLR Quantum Computing Initiative</a>.&quot;We are pursuing a range of technological approaches, which we can then evaluate and apply. This is the only way of researching the advantages and disadvantages of different architectures for quantum computers. The strong scientific basis for quantum technologies will be strengthened in industry and research. The initiative targets existing start-ups and the founding of new ones,&quot; says Anke Kaysser-Pyzalla, Chair of the DLR Executive Board.<h2>System with at least 64 qubits planned</h2>Qubits based on photons have the advantage that they can be manipulated using tried and tested optical methods. These qubits &ndash; the arithmetic building blocks &ndash; are also thought to be easily scalable, so their number, and thus their computing power, can be significantly increased. The light particles for the photonic platforms can be produced by a laser. The greatest challenge presented by photonic systems is that photons are comparatively elusive and do not interact directly with each other. Quantum computers cannot function without interaction or&nbsp;entanglement.Creating&nbsp;quantum gates to overcome this hurdle requires new, innovative concepts. The photonic quantum computer in this project works differently from most quantum computers, such as those based on&nbsp;ions or&nbsp;NV centres. Instead of running quantum gates in a circuit-like manner, calculations are conducted through a series of measurements. This process is called measurement-based quantum computing.An eight-qubit quantum processor should be ready within three years. The researchers are aiming to achieve a system with at least 64 qubits by the end of the project. QuiX Quantum&#39;s photonic quantum computer processes information in an entangled quantum state made up of many photons. &quot;The entanglement of the photons occurs in the waveguides of our processors. The waveguides guide the light through the processor in the same way as the electrical conductor paths in a conventional processor. With active control elements, we can allow photons to interact (interfere) or specifically change their phase. Adaptive measurements can be made on the generated quantum state with the help of single photon detectors. This is how qubits are encoded, processed and measured,&quot; explains Stefan Hengesbach of QuiX Quantum. The company is also supplied by M&uuml;nster-based start-up&nbsp;<a href="https://pixelphotonics.com/" target="_blank" title="External link Pixel Photonics">Pixel Photonics</a>. QuiX Quantum has already developed a photonic processor in the form of a reprogrammable interferometer. As part of the contract, QuiX Quantum will provide DLR with a prototype of this processor, complete with 12 input channels next year. This will allow researchers to acquire some initial experience in the use of a photonic quantum computer.<h2>DLR institutes and QuiX Quantum jointly developing applications</h2>Over the coming weeks, QuiX Quantum employees will move into the DLR innovation centre in&nbsp;<a href="https://www.dlr.de/content/en/sites/ulm.html" target="_blank" title="Ulm">Ulm</a>. The companies work in close proximity to the DLR institutes there and those at the similar innovation centre in&nbsp;<a href="https://www.dlr.de/content/en/sites/hamburg.html" target="_blank" title="Hamburg">Hamburg</a> &quot;By bringing QuiX Quantum on board, we are integrating another company into our Quantum Computing Initiative and developing the range of technologies at our disposal, in this case specifically for photonic quantum computing. Another player in the quantum computing ecosystem will assist us in advancing with this technology at our innovation centre in Ulm,&quot; says Robert Axmann, Head of the DLR Quantum Computing Initiative. The photonic platform planned here will pave the way for universal computing operations, which means that the prototype quantum computer is not limited to solving specific problems. The DLR institutes will develop applications on this system in collaboration with the start-up.

Structure of a photonic quantum computer. Credit: ©QuiX Quantum/Daniel Verkijk

The start-up QuiX Quantum will develop prototype photonic quantum computers over the next four years.

Computing with light

In this episode, we talk about how performance limitations of current microchips are being addressed by utilizing novel materials like graphene and bioinspired designs to address the needs of next generation computing and electronics. As always, you can find these and other interesting &amp; impactful engineering articles on Wevolver.com.&nbsp;<iframe height="200px" width="100%" frameborder="no" scrolling="no" seamless="" src="https://player.simplecast.com/4c563405-4ade-4b6a-9070-a75a7d327eef?dark=false" class="fr-draggable" data-lf-yt-playback-inspected-kn9eq4roawkarlvp="true" data-lf-form-tracking-inspected-kn9eq4roawkarlvp="true" data-lf-vimeo-playback-inspected-kn9eq4roawkarlvp="true"></iframe><hr>This podcast is sponsored by <a href="https://www2.mouser.com/" id="isPasted" rel="nofollow" target="_blank">Mouser Electronics</a>. &nbsp; &nbsp;&nbsp;<img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjU0MDAxNTk1MjgwLU1vdXNlci1zcG9uc29yLTEtYS5qcGciLCJlZGl0cyI6eyJyZXNpemUiOnsid2lkdGgiOjk1MCwiZml0IjoiY292ZXIifX19" style="width: 766px;" class="fr-fic fr-dib"><hr>(3:46) - Graphene-hBN Computing(16:44) - Spiderweb MicrochipsEpisode 72 was brought to you by Mouser Electronics, Farbod &amp; Daniel’s favorite electronics distributor. Click <a href="https://www.mouser.com/applications/wide-bandgap-beyond-silicon/" target="_blank">here</a> to read the article discussing &nbsp;how scientists are looking beyond silicon for the future of computer chips.<hr>About the podcast:Every day, some of the most innovative universities, companies, and individual technology developers share their knowledge on Wevolver. To ensure we can also provide this knowledge for the growing group of podcast listeners, we started a collaboration with two young engineers, Daniel Scott Mitchell &amp; Farbod Moghaddam who discuss the most interesting content in this podcast series.&nbsp;To learn more about this show, please visit the <a href="https://www.wevolver.com/profile/the.next.byte" target="_blank">shows page</a>. By following the page, you will get automatic updates by email when a new show is published.Be sure to give us a follow and review on <a href="https://podcasts.apple.com/nl/podcast/the-next-byte/id1548255861?l=en" rel="nofollow" target="_blank">Apple</a> podcasts, <a href="https://open.spotify.com/show/6lPPsRtegnivsRUEsQ09R7?si=IPMiah7xT_apJtPjqvXMlA" rel="nofollow" target="_blank">Spotify</a>, and most of your favorite podcast platforms!Take a few seconds to leave us a review. It really helps! <a href="https://apple.co/2RIsbZ2" rel="nofollow" target="_blank">https://apple.co/2RIsbZ2&nbsp;</a>if you do it and send us proof, we’ll give you a shoutout on the show.

In this episode, we talk about how performance limitations of current microchips are being addressed by utilizing novel materials like graphene and bioinspired designs to address the needs of next generation computing and electronics.

Podcast: Spiderweb Inspired & Graphene Enhanced Microchips

This article was first published on <a href="https://news.mit.edu/2022/quantum-circuits-robust-noise-0321" id="isPasted" rel="noopener noreferrer" target="_blank">MIT News</a>.<hr>Quantum computing continues to advance at a rapid pace, but one challenge that holds the field back is mitigating the noise that plagues quantum machines. This leads to much higher error rates compared to classical computers.This noise is often caused by imperfect control signals, interference from the environment, and unwanted interactions between qubits, which are the building blocks of a <a href="https://news.mit.edu/2020/explained-quantum-engineering-1210" target="_blank">quantum computer</a>. Performing computations on a quantum computer involves a “quantum circuit,” which is a series of operations called quantum gates. These quantum gates, which are mapped to the individual qubits, change the quantum states of certain qubits, which then perform the calculations to solve a problem.But quantum gates introduce noise, which can hamper a quantum machine’s performance.Researchers at MIT and elsewhere are working to overcome this problem by developing a technique that makes the quantum circuit itself resilient to noise. (Specifically, these are “parameterized” quantum circuits that contain adjustable quantum gates.) The team created a framework that can identify the most robust quantum circuit for a particular computing task and generate a mapping pattern that is tailored to the qubits of a targeted quantum device.Their framework, called QuantumNAS (noise adaptive search), is much less computationally intensive than other search methods and can identify quantum circuits that improve the accuracy of machine learning and quantum chemistry tasks. When the researchers used their technique to identify quantum circuits for real quantum devices, their circuits outperformed those generated using other methods.“The key idea here is that, without this technique, we have to sample each individual quantum circuit architecture and mapping scenario in the design space, train them, evaluate them, and if it is not good we have to throw it away and start over. But using this method, we can obtain many different circuits and mapping strategies at once with no need for many times of training,” says Song Han, an associate professor in the Department of Electrical Engineering and Computer Science (EECS) and senior author of the paper.Joining Han on the paper are lead author Hanrui Wang and Yujun Lin, both EECS graduate students; Yongshan Ding, an assistant professor of computer science at Yale University; David Z. Pan, the Silicon Laboratories Endowed Chair in Electrical Engineering at the University of Texas at Austin, and UT Austin grad student Jiaqi Gu; Fred Chong, the Seymour Goodman Professor in the Department of Computer Science at the University of Chicago; and Zirui Li, an undergraduate student at the Shanghai Jiao Tong University. The research will be presented at the IEEE International Symposium on High-Performance Computer Architecture.<h2>Many design choices</h2>Constructing a parameterized quantum circuit involves selecting a number of quantum gates, which are physical operations the qubits will perform. This is no easy task, since there are many types of gates to choose from. A circuit can also have any number of gates, and the positions of those gates — which physical qubits they map to — can vary.“With so many different choices, the design space is extremely large. The challenge is how to design a good circuit architecture. With QuantumNAS, we want to design that architecture so it can be very robust to noise,” says Wang.The researchers focused on variational quantum circuits, which use quantum gates with trainable parameters that can learn a machine learning or quantum chemistry task. To design a variational quantum circuit, typically a researcher must either hand-design the circuit or use rule-based methods to design the circuit for a particular task, and then try to find the ideal set of parameters for each quantum gate through an optimization process.In the naïve search method, in which possible circuits are evaluated individually, the parameters for each candidate quantum circuit must be trained, which results in a massive computational overhead. But the researcher also must identify the ideal number of parameters and the circuit architecture in the first place.In classical <a href="https://news.mit.edu/2017/explained-neural-networks-deep-learning-0414" target="_blank">neural networks</a>, including more parameters often increases the model’s accuracy. But in variational quantum computing, more parameters require more quantum gates, which introduce more noise.With QuantumNAS, the researchers seek to reduce the overall search and training cost while identifying the quantum circuit that contains the ideal number of parameters and appropriate architecture to maximize accuracy and minimize noise.<h2>Building a “SuperCircuit”</h2>To do that, they first design a “SuperCircuit,” which contains all the possible parameterized quantum gates in the design space. That SuperCircuit will be used to generate smaller quantum circuits that can be tested.They train the SuperCircuit once, and then because all other candidate circuits in the design space are subsets of the SuperCircuit, they inherit corresponding parameters that have already been trained. This reduces the computational overhead of the process.Once the SuperCircuit has been trained, they use it to search for circuit architectures that meet a targeted objective, in this case high robustness to noise. The process involves searching for quantum circuits and qubit mappings at the same time using what is known as an evolutionary search algorithm.This algorithm generates some quantum circuit and qubit mapping candidates, then evaluates their accuracy with a noise model or on a real machine. The results are fed back to the algorithm, which selects the best performing parts and uses them to start the process again until it finds the ideal candidates.“We know that different qubits have different properties and gate error rates. Since we’re only using a subset of the qubits, why don’t we use the most reliable ones? We can do this through co-search of the architecture and qubit mapping,” Wang explains.Once the researchers have arrived at the best quantum circuit, they train its parameters and perform quantum gate pruning by removing any quantum gates that have values close to zero, since they don’t contribute much to the overall performance. Removing theses gates reduces sources of noise and further improves the performance on real quantum machines. Then they fine-tune the remaining parameters to recover any accuracy that was lost.After that step is complete, they can deploy the quantum circuit to a real machine.When the researchers tested their circuits on real quantum devices, they outperformed all the baselines, including circuits hand-designed by humans and others made using other computational methods. In one experiment, they used QuantumNAS to produce a noise-robust quantum circuit that was used to estimate the ground state energy for a particular molecule, which is an important step in quantum chemistry and drug discovery. Their method made a more accurate estimation than any of the baselines.Now that they have shown the effectiveness of QuantumNAS, they want to use these principles to make the parameters in a quantum circuit robust to noise. The researchers also want to improve the scalability of a quantum neural network by training a quantum circuit on a real quantum machine, rather than a classical computer.“This is an interesting work that searches for noise-robust ansatz and qubit mapping of parametric quantum circuits,” says Yiyu Shi, a professor of computer science and engineering at the University of Notre Dame, who was not involved with this research. “Different from the naive search method that trains and evaluates a large number of candidates individually, this work trains a SuperCircuit and uses it to evaluate many candidates, which is much more efficient."“In this work, Hanrui and collaborators alleviate the challenge of searching for an efficient parametrized quantum circuit by training one SuperCircuit and using it to evaluate many candidates which becomes very efficient as it requires one training procedure. Once the SuperCircuit is trained, it can be used to search for the circuit ansatz and qubit mapping. After training the SuperCircuit, we can use it to search for the circuit ansatz and qubit mapping. The evaluation process is done using noise models or running on the real quantum machine,” says Sona Najafi, a research scientist at IBM Quantum who was not involved with this work. “The protocol has been tested using IBMQ quantum machines on VQE and QNN tasks demonstrating more accurate ground state energy and higher classification accuracy.”&nbsp;To encourage more work in this area, the researchers created an open-source library, called <a href="https://github.com/mit-han-lab/torchquantum" target="_blank">TorchQuantum</a>, that contains information about their projects, tutorials, and tools that can be used by other research groups.<hr>"Reprinted with permission of&nbsp;<a href="https://news.mit.edu/2022/quantum-circuits-robust-noise-0321" id="isPasted" rel="noopener noreferrer" target="_blank">MIT News</a>"

Researchers have developed a technique for making quantum computing more resilient to noise, which boosts performance. Image: Christine Daniloff, MIT

Researchers have developed a technique for making quantum computing more resilient to noise, which boosts performance.

Making quantum circuits more robust

This article was first published on <a href="https://news.mit.edu/2022/physicists-discover-secret-sauce-behind-exotic-properties-new-quantum-material-0121" id="isPasted" rel="noopener noreferrer" target="_blank">MIT News</a>.<hr>MIT physicists and colleagues have discovered the “secret sauce” behind some of the exotic properties of a new quantum material that has transfixed physicists due to those properties, which include superconductivity. Although theorists had predicted the reason for the unusual properties of the material, known as a kagome metal, this is the first time that the phenomenon behind those properties has been observed in the laboratory.“The hope is that our new understanding of the electronic structure of a kagome metal will help us build a rich platform for discovering other quantum materials,” says Riccardo Comin, the Class of 1947 Career Development Associate Professor of Physics at MIT, whose group led the study. That, in turn, could lead to a new class of superconductors, new approaches to quantum computing, and other quantum technologies.The work is&nbsp;<a href="https://www.nature.com/articles/s41567-021-01451-5" target="_blank">reported</a> in the Jan. 13 online issue of the journal&nbsp;Nature Physics.Classical physics can be used to explain any number of phenomena that underlie our world — until things get exquisitely small. Subatomic particles like electrons and quarks behave differently, in ways that are still not fully understood. Enter quantum mechanics, the field that tries to explain their behavior and resulting effects.The kagome metal at the heart of the current work is a new quantum material, or one that manifests the exotic properties of quantum mechanics at a macroscopic scale. In 2018 Comin and Joseph Checkelsky, MIT’s Mitsui Career Development Associate Professor of Physics, led the first study on the electronic structure of kagome metals, spurring interest into this family of materials. Members of the kagome metal family are composed of layers of atoms arranged in repeating units similar to a Star of David or sheriff’s badge. The pattern is also common in Japanese culture, particularly as a basket-weaving motif.“This new family of materials has attracted a lot of attention as a rich new playground for quantum matter that can exhibit exotic properties such as unconventional superconductivity, nematicity, and charge-density waves,” says Comin.Unusual propertiesSuperconductivity and hints of charge density wave order in the new family of kagome metals studied by Comin and colleagues were discovered in the laboratory of Professor Stephen Wilson at the University of California at Santa Barbara, where single crystals were also synthesized (Wilson is a coauthor of the&nbsp;Nature Physics&nbsp;paper). The specific kagome material explored in the current work is made of only three elements (cesium, vanadium, and antimony) and has the chemical formula CsV3Sb5.The researchers focused on two of the exotic properties that a kagome metal shows when cooled below room temperatures. At those temperatures, electrons in the material begin to exhibit collective behavior. “They talk to each other, as opposed to moving independently,” says Comin.One of the resulting properties is superconductivity, which allows a material to conduct electricity extremely efficiently. In a regular metal, electrons behave much like people dancing individually in a room. In a kagome superconductor, when the material is cooled to 3 kelvins (about -454 degrees Fahrenheit) the electrons begin to move in pairs, like couples at a dance. “And all these pairs are moving in unison, as if they were part of a quantum choreography,” says Comin.At 100 K, the kagome material studied by Comin and collaborators exhibits yet another strange kind of behavior known as charge density waves. In this case, the electrons arrange themselves in the shape of ripples, much like those in a sand dune. “They’re not going anywhere; they’re stuck in place,” Comin says. A peak in the ripple represents a region that is rich in electrons. A valley is electron-poor. “Charge density waves are very different from a superconductor, but they’re still a state of matter where the electrons have to arrange in a collective, highly organized fashion. They form, again, a choreography, but they’re not dancing anymore. Now they form a static pattern.”Comin notes that kagome metals are of great interest to physicists in part because they can exhibit both superconductivity and charge density waves. “These two exotic phenomena are often in competition with one another, therefore it is unusual for a material to host both of them.”<h2>The secret sauce?</h2>But what is behind the emergence of these two properties? “What causes the electrons to start talking to each other, to start influencing each other? That is the key question,” says first author Mingu Kang, a graduate student in the MIT Department of Physics also affiliated with the Max Planck POSTECH Korea Research Initiative. That’s what the physicists report in&nbsp;Nature Physics. “By exploring the electronic structure of this new material, we discovered that the electrons exhibit an intriguing behavior known as an electronic singularity,” Kang says. This particular singularity is named for Léon&nbsp;van Hove, the Belgian physicist who first discovered it.The van Hove singularity involves the relationship between the electrons’ energy and velocity. Normally, the energy of a particle in motion is proportional to its velocity squared. “It’s a fundamental pillar of classical physics that [essentially] means the greater the velocity, the greater the energy,” says Comin. Imagine a Red Sox pitcher hitting you with a fast ball. Then imagine a kid trying to do the same. The pitcher’s ball would hurt a lot more than the kid’s, which has less energy.What the Comin team found is that in a kagome metal, this rule doesn’t hold anymore. Instead, electrons traveling with different velocities happen to all have the same energy. The result is that the pitcher’s fast ball would have the same physical effect as the kid’s. “It’s very counterintuitive,” Comin says. He noted that relating the energy to the velocity of electrons in a solid is challenging and requires special instruments at two international synchrotron research facilities: Beamline 4A1 of the Pohang Light Source and Beamline 7.0.2 (MAESTRO) of the Advanced Light Source at Lawrence Berkeley National Lab.Comments Professor Ronny Thomale of the Universität Würzburg (Germany): "Theoretical physicists&nbsp;(including my group)&nbsp;have predicted&nbsp;the&nbsp;peculiar nature of van Hove singularities on the kagome lattice, a crystal structure made of corner-sharing triangles.&nbsp;Riccardo Comin has now provided the first experimental verification of these theoretical suggestions." Thomale was not involved in the work.When many electrons exist at once with the same energy in a material, they are known to interact much more strongly. As a result of these interactions, the electrons can pair up and become superconducting, or otherwise form charge density waves. “The presence of a van Hove singularity in a material that has both makes perfect sense as the common source for these exotic phenomena” adds Kang. “Therefore, the presence of this singularity is the ‘secret sauce’ that enables the quantum behavior of kagome metals.”The team’s new understanding of the relationship between energy and velocities in the kagome material “is also important because it will enable us to establish new design principles for the development of new quantum materials,” Comin says. Further, “we now know how to find this singularity in other systems.”<h2>Direct feedback</h2>When physicists are analyzing data, most of the time that data must be processed before a clear trend is seen. The kagome system, however, “gave us direct feedback on what’s happening,” says Comin. “The best part of this study was being able to see the singularity right there in the raw data.”Additional authors of the Nature Physics paper are Shiang Fang of Rutgers University; Jeung-Kyu Kim, Jonggyu Yoo, and Jae-Hoon Park of Max Planck POSTECH/Korea Research Initiative and Pohang University of Science and Technology (Korea); Brenden Ortiz of the University of California, Santa Barbara; Jimin Kim of the Institute for Basic Science (Korea); Giorgio Sangiovanni of the Universität Würzburg (Germany); Domenico Di Sante of the University of Bologna (Italy) and the Flatiron Institute; Byeong-Gyu Park of Pohang Light Source (Korea); Sae Hee Ryu, Chris Jozwiak, Aaron Bostwick and Eli Rotenberg of Lawrence Berkeley National Laboratory; and Efthimios Kaxiras of Harvard University.<hr>"Reprinted with permission of <a href="https://news.mit.edu/2022/physicists-discover-secret-sauce-behind-exotic-properties-new-quantum-material-0121" id="isPasted" rel="noopener noreferrer" target="_blank">MIT News</a>"

A visualization of the zero-energy electronic states — also known as a "Fermi surface" — from the kagome material studied by MIT’s Riccardo Comin and colleagues Credits: Image courtesy of the Comin Laboratory.

New work on superconducting kagome metal will aid design of other unusual quantum materials, with many potential applications.

Physicists discover "secret sauce" behind exotic properties of a new quantum material

A semiconducting material that performed a quantum “flip” from a conductor to an insulator above room temperature has been developed at the University of Michigan. It potentially brings the world closer to a new generation of quantum devices and ultra-efficient electronics. Observed in two-dimensional layers of tantalum sulfide only a single atom thick, the exotic electronic structure that supported this quantum flip was previously only stable at ultra-cold temperatures of -100 degrees Fahrenheit. The new material remains stable at up to 170 degrees Fahrenheit.“We’ve opened up a new playground for the future of electronic and quantum materials,” said Robert Hovden, a U-M assistant professor of materials science and engineering and corresponding author on the paper in Nature Communications. “It represents a whole new way to access exotic states.” Hovden explains that exotic quantum properties—like the ability to switch from a conductor to an insulator—could be key to the next generation of computing, providing more ways to store information and faster switching between states. That could lead to far more powerful and more energy-efficient devices.&nbsp;<img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjQyNzY1ODg2OTYzLU1pY3Jvc2NvcHlfYmVmb3JlX2FmdGVyLTYxMXgxMDI0LmpwZyIsImVkaXRzIjp7InJlc2l6ZSI6eyJ3aWR0aCI6OTUwLCJmaXQiOiJjb3ZlciJ9fX0=" style="width: 766px;" class="fr-fic fr-dib">This electron microscopy image shows the atoms within individual two-dimensional layers of tantalum sulfide before and after the heat treating process. Before heat-treating, all layers are bonded with octahedral geometry. After heat-treating, most layers are bonded with prismatic geometry. The remaining octahedral layers exhibit ordered charged density waves and have switched from conductor to insulator. The white scale bar represents two nanometers. Credit: Suk Hyun Sun, University of Michigan&nbsp;Today’s electronics use tiny electronic switches to store data; ”on” is one and “off” is zero, and the data disappears when the power is turned off. Future devices could use other states, like “conductor” or “insulator” to store digital data, requiring only a quick blip of energy to switch between states rather than a steady stream of electricity.&nbsp;In the past, however, such exotic behavior has only been observed in materials at super-cold temperatures. The ultimate goal is to develop materials that can quickly “flip” from one state to another on demand and at room temperature. Hovden says this research could be an important step in that direction.“Previous research at ultra-cold temperatures has shown that it’s possible to make these kinds of flips happen on demand, over and over again,” he said. “That wasn’t the focus of this project, but the fact that we were able to keep even one flip stable at room temperature opens a lot of exciting possibilities.”The flip from conductor to insulator is supported by a phenomenon called a charge density wave—an ordered, crystal-like pattern of positive and negative electrical charge that occurs spontaneously in certain conditions. “Charge density waves have been observed before in bulk samples of tantalum sulfide, but the material had to be at ultra-cold temperatures,” Hovden said. “By interleaving several two-dimensional layers together, we were able to make it much more stable.” The team began by fabricating a sample of several single-atom-thick layers of tantalum sulfide sandwiched together. Each layer was a semiconductor in what’s called an octahedral state, which refers to a specific arrangement of tantalum and sulfur atoms. And while some charge density waves were present, they were too unstable and disordered to give rise to exotic behavior like a conductor-insulator flip.<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1642767067015-ezgif-2-46b645eee2.gif" style="width: 766px;" class="fr-fic fr-dib">This electron microscopy video shows layers of tantalum sulfide converting from octahedral to prismatic state during the heat-treating process. Video: Suk Hyun Sun, University of MichiganBut Suk Hyun Sung, a graduate researcher in Hovden’s lab and the first author on the paper, changed the sample’s properties by heating it in an oxygen-free environment while observing the process under an electron microscope. As the sample heated, layers began to switch, one by one, into a prismatic state—a different arrangement of the same atoms.When most, but not all, layers had switched to prismatic state, Sung cooled the sample back to room temperature. He found that the layers that remained in the octahedral state were exhibiting charge density waves that were orderly and stable, and stayed that way at temperatures of up to 170 degrees Fahrenheit. In addition, those layers had flipped from semiconductors to insulators.“Most 2D materials are subject to all the defects of whatever they’re sitting on, whatever’s in the air, and that makes them very unstable” Sung said. “But we discovered that when octahedral layers are nestled between several prismatic layers, they’re much more stable.” The team is examining the phenomenon further, tweaking more variables of the process and testing mechanisms to control the exotic behaviors spurred by the charge density waves. For now, the new discovery has given them an important glimpse into the workings of quantum states and two-dimensional materials.<hr>The work was performed in part at the <a href="https://lnf.umich.edu/" target="_blank">U-M Lurie Nanofabrication Facility</a>, and it includes contributions from researchers at Cornell University, the U.S. Naval Research Laboratory and the Chinese Academy of Sciences.The research team also includes U-M materials science and engineering assistant professor John T. Heron; U-M assistant professor of electrical engineering and computer science Parag B. Deotare; U-M materials science and engineering graduate student researchers Steve Novakov, Xiangpeng Luo, Jiseok Gim and Nguyen Vu; U-M electrical engineering and computer science graduate student research assistant Zidong Li, U-M College of Literature, Science and the Arts Associate Professor of Physics Kai Sun; U-M College of Literature, Science and the Arts Assistant Professor of Physics Liuyan Zhao; Kavil Institute at Cornell for Nanoscale Science researcher Lena F. Kourkoutis; Cornell Department of Physics researcher Ismail El Baggari; U.S Naval Research Laboratory material science and technology researcher Todd Brintlinger; and Chinese Academy of Sciences Institute of Solid State Physics researchers Yu Liu, Wenjian Lu and Yuping Sun.

Discovery could pave the way to high speed, low-energy quantum computing.

Quantum tech: Semiconductor "flipped" to insulator above room temp

This article was first published on <a href="https://www.csail.mit.edu/news/language-quantum-computing" id="isPasted" rel="noopener noreferrer" target="_blank">MIT News</a>.<hr>Time crystals. Microwaves. Diamonds. What do these three disparate things have in common?Quantum computing. Unlike traditional computers that use bits, quantum computers use qubits to encode information as zeros or ones, or both at the same time. Coupled with a cocktail of forces from quantum physics, these fridge-sized machines can process a whole lot of information – but they’re far from flawless. Just like our regular computers, we need to have the right programming languages to properly compute on quantum computers.Programming quantum computers requires awareness of something called “entanglement”, a&nbsp;<a href="https://www.afr.com/technology/quantum-computing-101-what-s-superposition-entanglement-and-a-qubit-20191218-p53l2j" target="_blank">computational multiplier for qubits</a> of sorts, which translates to a lot of power. When two qubits are entangled, actions on one qubit can change the value of the other even when they are physically separated, giving rise to Einstein’s characterization of “spooky action at a distance.” But that potency is equal parts a source of weakness. When programming, discarding one qubit without being mindful of its entanglement with another qubit can destroy the data stored in the other, jeopardizing the correctness of the program.Scientists from MIT’s Computer Science and Artificial Intelligence (CSAIL) aimed to do some unraveling by creating their own programming language for quantum computing called “Twist.” Twist can describe and verify which pieces of data are entangled in a quantum program, through a language a classical programmer can understand. The language uses a concept called purity, which enforces the absence of entanglement and results in more intuitive programs, with ideally fewer bugs. For example, a programmer can use Twist to say that the temporary data generated as garbage by a program is not entangled with the program’s answer, making it safe to throw away.While the nascent field can feel a little flashy and futuristic, with images of mammoth wiry gold machines coming to mind, quantum computers have potential for computational breakthroughs in classically unsolvable tasks, like cryptographic and communication protocols, search, and computational physics and chemistry. One of the key challenges in computational sciences is dealing with the complexity of the problem and the amount of computation needed. Whereas a classical digital computer would need a very large exponential number of bits to be able to process such a simulation, a quantum computer could do it, potentially, using a very small number of qubits – if the right programs are there.“Our language Twist allows a developer to write safer quantum programs by explicitly stating when a qubit must not be entangled with another,” said MIT PhD student Charles Yuan, the lead author on a paper about Twist. “Because understanding quantum programs requires understanding entanglement, we hope that Twist paves the way to languages that make the unique challenges of quantum computing more accessible to programmers.”<h2>Untangling quantum entanglement</h2>Imagine a wooden box that has a thousand cables protruding out from one side. You can pull any cable all the way out of the box, or push it all the way in.After you do this for a while, the cables form a pattern of bits – zeros and ones – depending on whether they’re in or out. This box represents the memory of a classical computer. A program for this computer is a sequence of instructions for when and how to pull on the cables.Now imagine a second, identical looking box. This time, you tug on a cable, and see that as it emerges, a couple of other cables are pulled back inside. Clearly, inside the box, these cables are somehow entangled with each other.The second box is an analogy for a quantum computer, and understanding the meaning of a quantum program requires understanding the entanglement present in its data. But detecting entanglement is not straightforward. You can’t see into the wooden box, so the best you can do is try pulling on cables and carefully reason about which are entangled. In the same way, quantum programmers today have to reason about entanglement by hand. This is where the design of Twist helps massage some of those interlaced pieces.&nbsp;The scientists designed Twist to be expressive enough to write out programs for well-known quantum algorithms and identify bugs in their implementations. To evaluate Twist's design, they modified the programs to introduce some kind of bug that would be relatively subtle for a human programmer to detect, and showed that Twist could automatically identify the bugs and reject the programs.They also measured how well the programs performed in practice in terms of runtime, which had less than four percent overhead over existing quantum programming techniques.For those wary of quantum’s “seedy” reputation in its potential to break encryption systems, Yuan says it’s still not very well known to what extent quantum computers will actually be able to reach their performance promises in practice. “There's a lot of research that's going on in post-quantum cryptography, which exists because even quantum computing is not all-powerful. So far, there's a very specific set of applications in which people have developed algorithms and techniques where a quantum computer can outperform classical computers.”&nbsp;An important next step is using Twist to create higher-level quantum programming languages. Most quantum programming languages today still resemble assembly language, stringing together low-level operations, without mindfulness towards things like data types and functions, and what’s typical in classical software engineering.“Quantum computers are error-prone and difficult to program. By introducing and reasoning about the ‘purity’ of program code, Twist takes a big step towards making quantum programming easier by guaranteeing that the quantum bits in a pure piece of code cannot be altered by bits not in that code,” says Fred Chong, the Seymour Goodman Professor of Computer Science at the University of Chicago and Chief Scientist at Super.tech.&nbsp;<hr>Reprinted with permission of&nbsp;<a href="https://www.csail.mit.edu/news/language-quantum-computing" id="isPasted" rel="noopener noreferrer" target="_blank">MIT News</a>"

Quantum computing. Unlike traditional computers that use bits, quantum computers use qubits to encode information as zeros or ones, or both at the same time.

A language for Quantum computing

<div id="isPasted" itemprop="description">“IBM and Google currently have the world’s most powerful quantum computers,” says Prof. Edoardo Charbon, head of the Advanced Quantum Architecture Laboratory (AQUA Lab) in EPFL’s School of Engineering. “IBM has just unveiled a 127-qubit machine, while Google’s is 53 qubits.” The scope for making quantum computers even faster is limited, however, due to an upper bound on the number of qubits. But a team of engineers led by Charbon, in collaboration with researchers in the U.K., has just developed a promising method for breaking through this technological barrier. Their approach can read qubits more efficiently, meaning more of them can be packed into quantum processors. Their findings appear in Nature Electronics.<h2>Biochemistry and cryptography</h2>Quantum computers don’t work like the computers we’re used to. Instead of having a separate processor and memory chip, the two are combined into a single unit known as a qubit. These computers use quantum properties such as superposition and entanglement to perform complicated calculations that regular computers could never do in a reasonable timeframe. Potential applications for quantum computers include biochemistry,cryptography and more. The machines used by research groups today have around a dozen qubits. “Our challenge now is to interconnect more qubits into quantum processors – we’re talking hundreds, even thousands – in order to boost the computers’ processing power,” says Charbon. The number of qubits is currently limited by the fact that there’s no technology yet available that can read all the qubits rapidly. “Complicating things further, qubits operate at temperatures close to absolute zero, or –273.15oC,” says Charbon. “That makes reading and controlling them even harder. What engineers typically do is use machines at room temperature and control each qubit individually.”<h2>“It’s a real breakthrough”</h2>Andrea Ruffino, a PhD student at Charbon’s lab, has developed a method enabling nine qubits to be read simultaneously and effectively. What’s more, his approach could be scaled up to larger qubit matrices. “Our method is based on using time and frequency domains,” he explains. “The basic idea is to reduce the number of connections by having three qubits work with a single bond.” EPFL doesn’t have a quantum computer, but that didn’t stop Ruffino. He found a way to emulate qubits and run experiments under nearly the same conditions as those in a quantum computer. “I incorporated quantum dots, which are nanometer-sized semiconductor particles, into a transistor. That gave me something that works the same as qubits,” says Ruffino. He’s the first PhD student in the AQUA Lab to study this topic for his thesis. “Andrea showed that his method works with integrated circuits on regular computer chips, and at temperatures approaching qubit ones,” says Charbon. “It’s a real breakthrough that could lead to systems of large qubit matrices integrated with the necessary electronics. The two types of technology could work together simply, effectively and in a reproducible manner.”<hr>References</div><a href="https://www.nature.com/articles/s41928-021-00687-6" rel="noopener" target="_blank">"A cryo-CMOS chip that integrates silicon quantum dots and multiplexed dispersive readout electronics",&nbsp;Andrea Ruffino,&nbsp;Tsung-Yeh Yang,&nbsp;John Michniewicz,&nbsp;Yatao Peng,&nbsp;Edoardo Charbon&nbsp;&amp;&nbsp;Miguel Fernando Gonzalez-Zalba</a>

Engineers at EPFL have developed a method for reading several qubits – the smallest unit of quantum data – at the same time. Their method paves the way to a new generation of even more powerful quantum computers.

Making quantum computers even more powerful

The world's first room-temperature quantum computer is in the final stages of development and is set to be installed at the Pawsey Supercomputing Centre in Perth and activated later this year.&nbsp;Unlike other quantum computers, this lunchbox-sized invention does not need extreme sub-zero temperatures to work and is on the cusp of being the most powerful computer ever created. &nbsp;&nbsp;Quantum computers promise a new era in ultra-secure networks, artificial intelligence and therapeutic drugs, and will be able to solve certain problems much faster than today's computers.&nbsp;Scientists at The Australian National University (ANU) have invented the groundbreaking technology used in the new computer, and are a driving force of the spin-out company Quantum Brilliance that seeks to commercialise the next-generation device.&nbsp;Pawsey and Quantum Brilliance will collaborate with other Australian industry leaders and researchers to develop cutting-edge quantum applications in machine learning, logistics, defence and aerospace.&nbsp;ANU Vice-Chancellor Professor Brian Schmidt said Quantum Brilliance represents the future of quantum computing.&nbsp;"As Australia's national university, ANU is committed to creating the technologies and industries of tomorrow, today. This work is vital to ensuring the future prosperity of our nation and the world," Professor Schmidt said. &nbsp;<div class="fr-img-space-wrap"><img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1617015695876-20210323_ANU2902_Andrew_Horsley_ANU-web.jpg" style="width: 788px;" class="fr-fic fr-dib">Dr. Andrew Horsley, CEO of Quantum Brilliance. Photo: Jamie Kidston/ANU"Quantum Brilliance and its work to develop an affordable room temperature, lunchbox-sized quantum computer that will become part of everyday life is the perfect example of this.&nbsp;</div>"The University's goal to create a billion-dollar company in the next five years will happen by supporting research commercialisation for spin-outs like Quantum Brilliance. &nbsp;"Quantum Brilliance is a company in its early days. But while it is early days, backing it now could lead to huge payoffs for all of us."&nbsp;Quantum Brilliance, led by ANU physicists Dr Marcus Doherty and Dr Andrew Horsley, has used synthetic diamonds to develop quantum microprocessors. &nbsp;The team's innovative platform enables the high computational power of quantum computing to be used for more widespread applications.&nbsp;Dr Horsley, CEO of Quantum Brilliance, said the new computer will transform industries in Australia and around the world.&nbsp;"Because of our unique diamond-based technology, customers can run our quantum computers themselves, and we provide them a full set of tools to explore how quantum can help create new capabilities."&nbsp;Pawsey and Quantum Brilliance will join forces with other Australian industry leaders and researchers as part of Pawsey's <a href="https://anu.us2.list-manage.com/track/click?u=73b3c4bf45063d7aa04d62036&id=cbe395e4b1&e=a3d1be9eda" target="_blank">Quantum Pioneer Program</a> to develop cutting-edge quantum applications in machine learning, logistics, defence, aerospace, quantum finance and quantum research. "I am delighted to see active industry and researcher engagement with quantum computing," Pawsey's Executive Director Mark Stickells said. "We are excited to explore the potential of this technology for Australian researchers to further accelerate their scientific workflows using the potential of quantum computing within the advanced infrastructure of a national research supercomputing centre."

The world's first room-temperature quantum computer is in the final stages of development and is set to be installed at the Pawsey Supercomputing Centre in Perth and activated later this year.

World's first room-temp quantum computer set for release

In this episode, we discuss an AI algorithm that can streamline the mechanical design process, how quantum keys can thwart hackers, and a new generation of li-ion batteries. As always, you can find these and other interesting &amp; impactful engineering articles on Wevolver.com.<iframe height="200px" width="100%" frameborder="no" scrolling="no" seamless="" src="https://player.simplecast.com/65c9eedd-bd52-4a23-a02f-5e92faeaca81?dark=false" 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> EPISODE NOTES(0:57) Order Up! AI Finds the Right Material –&nbsp;Researchers from CMU and UCalgary made an AI algorithm to help designers choose the correct material for a part based on its intended end use.(6:15) Unique Testbed In Eindhoven Paves The Way For Unhackable 'Quantum Internet' –&nbsp;Eindhoven researchers have devised a method to protect our data from hackers with quantum computers.(10:51) New Technique Extends Next-Generation Lithium Metal Batteries –&nbsp;A group from Columbia added potassium to lithium ion batteries to make them safer and longer-lasting.&nbsp;--About the podcast:Every day, some of the most innovative universities, companies, and individual technology developers share their knowledge on Wevolver. To ensure we can also provide this knowledge for the growing group of podcast listeners, we started a collaboration with two young engineers, Daniel Scott Mitchell &amp; Farbod Moghaddam who discuss the most interesting content in this podcast series.&nbsp;To learn more about this show, please visit the <a href="https://www.wevolver.com/profile/the.next.byte" target="_blank">shows page</a>. By following the page, you will get automatic updates by email when a new show is published.Be sure to give us a follow and review on <a href="https://podcasts.apple.com/nl/podcast/the-next-byte/id1548255861?l=en" target="_blank">Apple</a> podcasts, <a href="https://open.spotify.com/show/6lPPsRtegnivsRUEsQ09R7?si=IPMiah7xT_apJtPjqvXMlA" target="_blank">Spotify</a>, and most of your favorite podcast platforms!

AI for Mechanical Design, the Key to Thwarting Quantum Hackers, Making Better Batteries

Podcast: AI for Mechanical Design, the Key to Thwarting Quantum Hackers, Making Better Batteries

For years, scientists have looked for ways to cool molecules down to ultracold temperatures, at which point the molecules should slow to a crawl, allowing scientists to precisely control their quantum behavior. This could enable researchers to use molecules as complex bits for quantum computing, tuning individual molecules like tiny knobs to carry out multiple streams of calculations at a time.While scientists have super-cooled atoms, doing the same for molecules, which are more complex in their behavior and structure, has proven to be a much bigger challenge.Now MIT physicists have found a way to cool molecules of sodium lithium down to 200 billionths of a Kelvin, just a hair above absolute zero. They did so by applying a technique called collisional cooling, in which they immersed molecules of cold sodium lithium in a cloud of even colder sodium atoms. The ultracold atoms acted as a refrigerant to cool the molecules even further.Collisional cooling is a standard technique used to cool down atoms using other, colder atoms. And for more than a decade, researchers have attempted to supercool a number of different molecules using collisional cooling, only to find that when molecules collided with atoms, they exchanged energy in such a way that the molecules were heated or destroyed in the process, called &ldquo;bad&rdquo; collisions.In their own experiments, the MIT researchers found that if sodium lithium molecules and sodium atoms were made to spin in the same way, they could avoid self-destructing, and instead engaged in &ldquo;good&rdquo; collisions, where the atoms took away the molecules&rsquo; energy, in the form of heat. The team used precise control of magnetic fields and an intricate system of lasers to choreograph the spin and the rotational motion of the molecules. As result, the atom-molecule mixture had a high ratio of good-to-bad collisions and was cooled down from 2 microkelvins to 220 nanokelvins.&ldquo;Collisional cooling has been the workhorse for cooling atoms,&rdquo; adds Nobel Prize laureate Wolfgang Ketterle, the John D. Arthur professor of physics at MIT.&nbsp;&ldquo;I wasn&rsquo;t convinced that our scheme would work, but since we didn&rsquo;t know for sure, we had to try it. We know now that it works for cooling sodium lithium molecules. Whether it will work for other classes of molecules remains to be seen.&rdquo;Their findings, published today in the journal Nature, mark the first time researchers have successfully used collisional cooling to cool molecules down to nanokelvin temperatures.Ketterle&rsquo;s coauthors on the paper are lead author Hyungmok Son, a graduate student in Harvard University&rsquo;s Department of Physics, along with MIT physics graduate student Juliana Park, and Alan Jamison, a professor of physics at the University of Waterloo and visiting scientist in MIT&rsquo;s Research Laboratory of Electronics.<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1586440710384-MIT-Molecular-Fridge-02.jpg">A new refrigerator for molecules. Sodium atoms (yellow spheres) collide with sodium-lithium molecules (combined-yellow-red-spheres). The atom-molecule mixture is trapped in an optical trap whose effective edge is shown as a white rim. As the trap is loosened (depicted as a dimmer rim), the most energetic sodium atoms leave the trap, providing evaporative cooling. The cooling is transferred to the molecules via elastic collisions. The frost on the molecules indicates that they have reached a temperature of 200 billionths of a degree Kelvin. Figure credit: Pilsu Heo at Micropicture (South Korea)<h2>Reaching ultralow temperatures</h2>In the past, scientists found that when they tried to cool molecules down to ultracold temperatures by surrounding them with even colder atoms, the particles collided such that the atoms imparted extra energy or rotation to the molecules, sending them flying out of the trap, or self-destructing all together by chemical reactions.The MIT researchers wondered whether molecules and atoms, having the same spin, could avoid this effect, and remain ultracold and stable as a result. They looked to test their idea with sodium lithium, a &ldquo;diatomic&rdquo; molecule that Ketterle&rsquo;s group experiments with regularly, consisting of one lithium and one sodium atom.&ldquo;Sodium lithium molecules are quite different from other molecules people have tried,&rdquo; Jamison says. &ldquo;Many folks expected those differences would make cooling even less likely to work. However, we had a feeling these differences could be an advantage instead of a detriment.&rdquo;The researchers fine-tuned a system of more than 20 laser beams and various magnetic fields to trap and cool atoms of sodium and lithium in a vacuum chamber, down to about 2 microkelvins &mdash; a temperature Son says is optimal for the atoms to bond together as sodium lithium molecules.Once the researchers were able to produce enough molecules, they shone laser beams of specific frequencies and polarizations to control the quantum state of the molecules and carefully tuned microwave fields to make atoms spin in the same way as the molecules. &nbsp;&ldquo;Then we make the refrigerator colder and colder,&rdquo; says Son, referring to the sodium atoms that surround the cloud of the newly formed molecules. &ldquo;We lower the power of the trapping laser, making the optical trap looser and looser, which brings the temperature of sodium atoms down, and further cools the molecules, to 200 billionths of a kelvin.&rdquo;The group observed that the molecules were able to remain at these ultracold temperatures for up to one second. &ldquo;In our world, a second is very long,&rdquo; Ketterle says. &ldquo;What you want to do with these molecules is quantum computation and exploring new materials, which all can be done in small fractions of a second.&rdquo;If the team can get sodium lithium molecules to be about five times colder than what they have so far achieved, they will have reached a so-called quantum degenerate regime where individual molecules become indistinguishable and their collective behavior is controlled by quantum mechanics. Son and his colleagues have some ideas for how to achieve this, which will involve months of work in optimizing their setup, as well as acquiring a new laser to integrate into their setup.&nbsp;&ldquo;Our work will lead to discussion in our community why collisional cooling has worked for us but not for others,&rdquo; Son says &ldquo;Perhaps we will soon have predictions how other molecules could be cooled in this way.&rdquo;

 A new “refrigerator” super-cools molecules to nanokelvin temperatures. The technique may enable more complex, molecule-based quantum computing.  Image: José-Luis Olivares, MIT

quantum computing

ORGANIZATIONS.

SHAPING THE INDUSTRY.

Keysight Test and Measurements

National Institute of Standards and Technology

Latest Posts