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

The highly automated and connected vehicles of the future will require powerful computer systems that perform sophisticated calculations and process huge amounts of data.&nbsp;30 partners from industry and research are developing suitable processors, interfaces and system architectures in the CeCaS project.&nbsp;The Karlsruhe Institute of Technology (KIT) is involved with two institutes in the project coordinated by Infineon.&nbsp;The Federal Ministry of Research supports CeCaS within the MANNHEIM initiative.&nbsp;The next generations of vehicles will be increasingly automated and networked in order to move more and more autonomously on the road and gradually relieve drivers.&nbsp;This requires enormous computing power, which only the most powerful computer systems can provide - whether in the vehicles themselves, along the roads or in the higher-level data centers.&nbsp;In addition to internal communication systems connected to the outside world, the vehicles require a central computer.&nbsp;This, in turn, consists of sub-components that perform sophisticated calculations, process huge amounts of data and have to achieve maximum reliability.<h2>KIT and TUM have assumed scientific coordination</h2>&nbsp;In the CeCaS (stands for: CentralCarServer) research project, 30 partners from industry and research are working on the architectures, the software engineering principles and the forms of implementation for future high-performance computers in cars.&nbsp;Infineon Technologies AG is responsible for coordinating the overall project.&nbsp;The KIT with Professor J&uuml;rgen Becker, head of the Institute for Information Processing Technology (ITIV), and Professor J&ouml;rg Henkel, head of the research area Embedded Electronic Systems at the Institute for Technical Informatics (ITEC-CES), as well as the Technical University of Munich ( TUM) with Professor Alois Knoll, Head of the Chair for Robotics, Artificial Intelligence and Real-Time Systems (AIR).&nbsp;&quot;The development of energy- and cost-efficient high-performance computers with full automotive qualifications, which meet the enormous demands on computing power and complexity in a scalable manner, makes a decisive contribution to the future viability and technological sovereignty of the German automotive industry,&quot; says Becker.&nbsp;In CeCaS, automotive supercomputing is created that meets the highest standards of safety and reliability.&nbsp;The project consortium designs processors, interfaces and system architectures.&nbsp;A flexible software environment is tailored to the requirements of the latest algorithms in automobiles - especially, but not only, for the use of artificial intelligence (AI).<h2>Hardware accelerators enable highly effective image processing</h2>In CeCaS, the KIT has taken over the design of novel multi-purpose hardware accelerators for highly effective image processing including the integration of reliable AI in the automobile.&nbsp;The innovative accelerators are connected via high-speed interfaces and integrated into the high-performance processors.&nbsp;The researchers are particularly focusing on the AI components between the sensor nodes and the central computer.&nbsp;In addition, the KIT is working within CeCaS on new development tools for the analysis and compliance with real-time criteria as well as on comprehensive benchmarking software for evaluating the hardware accelerator.&nbsp;&quot;Progress in automotive technology is directly dependent on progress in computer technology and information technology - but above all on the ability of the automotive industry to use modern chip technologies for itself,&quot; explains Becker.&nbsp;&quot;CeCaS supports the German automotive industry in playing a leading role in global competition, even in the digital age.&quot;&nbsp;<h2>About CeCaS</h2>The Federal Ministry of Education and Research (BMBF) is funding CeCaS in its MANNHEIM initiative, named after the birthplace of the automobile, with around 46 million euros.&nbsp;The total project volume is almost 90 million euros.&nbsp;CeCaS is scheduled for three years.The 30 cooperation partners of the MANNHEIM-CeCaS project are: Bosch, Continental Automotive, ZF Friedrichshafen, Hella, AVL Software &amp; Functions, Ambrosys, Infineon Technologies AG (coordination; with Infineon Technologies Dresden GmbH &amp; Co. KG and Infineon Technologies Semiconductor GmbH), core concept , Berlin Nanotest and Design, Missing Link Electronics, Inchron, Gl&uuml;ck Engineering, STTech, Steinbeis ZFW, Swissbit Germany, Karlsruhe Institute of Technology (KIT) with the institutes ITIV and ITEC-CES, FZI Research Center for Information Technology, Technical University of Munich with the chairs AIR , LIS and SEC, Munich University of Applied Sciences, L&uuml;beck University, Chemnitz University of Technology, Fraunhofer ENAS, IMWS, IPMS and IZM.&nbsp;

Computer systems in future highly automated and networked cars must perform sophisticated calculations, process huge amounts of data and achieve maximum reliability. (Icon graphic: © kaptn – stock.adobe.com, KIT)

The CeCaS research project creates processors, interfaces and system architectures for highly automated networked vehicles - KIT develops hardware accelerators and benchmarking software

Supercomputers to Control Cars of the Future

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

DTU Campus Service at Ris&oslash; operates a server park with supercomputers covering 3,500 square metres. However, the energy does not simply vanish into thin air, but is converted into heat by means of a heat pump at Ris&oslash; Campus. &ldquo;It&rsquo;s possible to channel up to 600 kilowatts of waste heat from the IT equipment into the district heating network at Ris&oslash; Campus. This means that we are self-sufficient with heating four months of the year,&rdquo; says Esben H&oslash;jrup, Technical Project Manager at DTU Campus Service (CAS). For the rest of the year, the surplus energy contributes to a district heating corresponding to 19 percent of Ris&oslash; campus&#39; energy consumption in the same period.<h2>Low carbon footprint</h2>Despite rising electricity prices, it is still worthwhile to run the heat pump that recovers the surplus energy. This is shown by figures from DTU&rsquo;s latest green accounts. &ldquo;We get close to six times as much heat into the district heating network than the electricity consumed by the heat pump. This ratio&mdash;which is called the COP value&mdash;is really impressive,&rdquo; says Bjarke Nonb&oslash;l, Engineer at DTU Campus Service (CAS). Electricity emits more CO2 than district heating&mdash;approximately 2.7 times more per megawatt hour&mdash;but as the heat pump generates about six times more heat, the heat pump is the solution with the lowest carbon emission. &quot;The carbon emission is only 45 per cent of what it would have been with district heating from a utility company,&rdquo; says Bjarke Nonb&oslash;l.<h2>Intelligent control</h2>If electricity prices continue to skyrocket&mdash;or if we have periods of power shortages&mdash;it may be necessary to turn off the heat pump to save power. &ldquo;You can&rsquo;t say that the price of electricity must reach as much as, for example, ten Danish kroner on average before it&rsquo;s worthwhile to buy district heating from outside. The ratio between the electricity price and the district heating price determines whether it&rsquo;s still worthwhile to run the heat pump,&rdquo; says Bjarke Nonb&oslash;l. Therefore, CAS Ris&oslash; is working to develop a system that can monitor in real time whether operation of the heat pump is worthwhile. &ldquo;We regulate our heat production by using PLC&mdash;which is a programmable device&mdash;a small computer specially developed for automation and control of a process, also called &lsquo;process control&rsquo;. For example, opening and closing a valve, controlling temperatures, or controlling flow and pressure,&quot; says Esben H&oslash;jrup and continues:&quot;What we still need to do is to program the fluctuating electricity prices into the PLC environment.&nbsp;In this way, we can completely automatically control whether the heat pump is to supply heat to the campus, or whether we are to get the heat from the district heating company.&rdquo;<h2>Critical look</h2>CAS Ris&oslash; has long been working to reduce its carbon emissions by reducing its energy consumption. At a time when power has become expensive and will remain expensive for a long time to come, however, it raises the question of whether it is a luxury to choose to use power for heating.&ldquo;We have to consider the current prices and our power consumption. Power can be used for most purposes, while heat can primarily be used for heating in buildings. Therefore, we also need to take a critical look at how we can optimize our current heat recovery model using intelligent control,&rdquo; concludes Esben H&oslash;jrup.<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1667560575661-Serverrum.jpg" style="width: 766px;" class="fr-fic fr-dib">In 2021, the server park contributed 2,525.5 [MWh] to DTU Ris&oslash; Campus&#39; district heating network, which makes a contribution of 19% of the total heat consumption.&nbsp;<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1667560610087-Varmeroer-Risoe.jpg" style="width: 766px;" class="fr-fic fr-dib">DTU Ris&oslash; Campus is supplied with heat from the server park during the summer months.&nbsp;

With a heat pump connected to DTU's data center, engineers Esben Højrup and Bjarke Nonbøl from DTU Campus Service utilize waste heat from the cooling servers. The heat pump supplies heat to the district heating network on Risø Campus.

A project at DTU Risø Campus shows that heat recovery is the most sustainable and economical choice—even at a time of rising electricity prices.

Heat from supercomputers recycled at DTU

Charged atoms cannot escape from an ion trap, as they are confined by an electromagnetic field. A laser, radio waves or microwaves can then change the state of the charged atoms (ions) in a targeted way, so that they become qubits, the building blocks of quantum computers. The German Aerospace Center (Deutsches Zentrum f&uuml;r Luft- und Raumfahrt; DLR) has now awarded contracts for the advancement of ion trap technology. Prototype quantum computers will be created within four years as part of the <a href="https://www.dlr.de/content/en/dossiers/2021/quantum-computing.html" target="_blank" title="Quantum computing">DLR Quantum Computing Initiative</a>.&quot;DLR is awarding contracts for five projects as part of its Quantum Computing Initiative, with the aim of creating qubits based on ion traps. This technology is considered highly promising and will be explored through targeted research. This takes us one step closer to a programmable, fault-tolerant quantum computer,&quot; says Anke Kaysser-Pyzalla, Chair of the DLR Executive Board. &quot;Through the close cooperation of business and science, synergies are created that strengthen the quantum computing ecosystem and thus also provide start-ups with new opportunities.&quot;The contracts amount to a total of 208.5 million euros. The gradual development of the systems will take place in several phases. &quot;By the end of the projects, we will have quantum computers based on ion trap technology, with at least 50 qubits. At the same time, we are building modular systems that can be scaled up to thousands of qubits,&quot; says Robert Axmann, Head of the DLR Quantum Computing Initiative. &quot;The academic and economic environment at our innovation centres makes them ideal for continued development.&quot;In the future, companies and their employees will be able to make use of offices, laboratories and a clean room in the DLR Innovation Centre in <a href="https://www.dlr.de/content/en/sites/hamburg.html" target="_blank" title="Hamburg">Hamburg</a>. Here and in the DLR Innovation Centre in <a href="https://www.dlr.de/content/en/sites/ulm.html" target="_blank" title="Ulm">Ulm</a>, the companies will also benefit from the close proximity to the DLR institutes and working groups and from working together on the challenges of quantum computing.<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1666879385110-vacuum-chamber-that-stores-ions.jpg" style="width: 766px;" class="fr-fic fr-dib">Vacuum chamber that stores ions. Credit: &copy;eleQtron GmbH<h2>Development work at the DLR Innovation Centre in Hamburg</h2>In a preliminary project, a consortium made up of <a href="https://www.nxp.com/company/about-nxp/worldwide-locations/germany:GERMANY" target="_blank" title="External link NXP Semiconductors Germany GmbH">NXP Semiconductors Germany</a> (Hamburg), <a href="https://www.eleqtron.com/" target="_blank" title="External link eleQtron GmbH">eleQtron</a> (Siegen) and <a href="https://parityqc.com/" target="_blank" title="External link Parity Quantum Computing Germany GmbH">Parity Quantum Computing Germany</a> (Munich) will provide a 10-qubit demonstration model, scheduled to start operation in late 2023. Users will be able to use this quantum computer to gain experience with ion trap systems and advance their development.Two projects involve building prototype quantum computers with at least 50 fully functional qubits on a chip. <a href="https://universalquantum.com/" target="_blank" title="External link Universal Quantum Deutschland GmbH">Universal Quantum Deutschland</a> (D&uuml;sseldorf) and the consortium of <a href="https://qudora.com/" target="_blank" title="External link QUDORA Technologies GmbH">Qudora Technologies</a> (Braunschweig) and NXP Semiconductors Germany (Hamburg) are each developing their own systems. The chip is scalable, which means that the number of qubits and computing power can be increased. Error susceptibility is considered to be one of the greatest challenges in quantum computing, so one area of focus is ensuring that the chip can correct faults.In two other projects, modular, scalable quantum computers are being developed on the basis of ion traps. This involves networking several chips to form a universal quantum computer architecture. The special thing about this is that each module is its own small quantum processor with 10 qubits each. This structure will later grow to comprise many chips with thousands of qubits. Universal Quantum Deutschland (D&uuml;sseldorf) and NXP Semiconductors Germany / eleQtron / Parity Quantum Computing Germany are developing these modular quantum computer prototypes on behalf of DLR.<h2>Ion trap qubits have a relatively long coherence time</h2>&quot;Ion trap systems allow universal arithmetic operations. They are not dedicated to solving specific tasks,&quot; explains Karla Loida, Project Manager for the Quantum Computing Initiative. &quot;Quantum computers based on ion traps have a number of advantages: the qubits are comparatively stable and offer superlative gate properties &ndash; a prerequisite for building high-quality quantum computers. Integration on microchips and innovative chip designs mean that scalability is now within reach.&quot; The technologies required for construction have now reached maturity. Laser systems can be used to provide the necessary cooling and targeted manipulation of qubits. Integration on microchips has also proven successful.The prototype quantum computers developed as part of the projects will be used in research and development at DLR and accessed via a network.<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1666879415163-quantum-processor-using-ion-trap-technology.jpg" style="width: 766px;" class="fr-fic fr-dib">Quantum processor using ion trap technology. Credit: &copy;QUDORA Technologies GmbH<h2>The DLR Quantum Computing Initiative</h2>There are different concepts for the development of quantum computers. It is still unclear which concept will ultimately prevail. DLR is supporting various technology projects in tandem and bringing its own skills and areas of focus to bear on the research and development work involved. Over the next four years, prototype quantum computers with different architectures will be built and the associated technologies and applications developed as part of the <a href="https://www.dlr.de/content/en/dossiers/2021/quantum-computing.html" target="_blank" title="Quantum computing">Quantum Computing Initiative</a>. DLR is getting companies, start-ups and other research institutions involved so that all of the partners can make significant advances together. DLR has been granted funding for this purpose by the 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>), enabling it to award large-scale contracts to companies through tenders.<h2>Rapid calculations with qubits</h2>Quantum computers are a key technology for the future: they can carry out calculations and simulations in specific areas of application much faster than conventional supercomputers. They can be used, for instance, in the transport and energy sector, but also in basic research or to operate satellites. Quantum computers work on the basis of quantum physics. Their quantum bits (qubits) can assume the states 0 and 1 at the same time &ndash; not just one after the other, like conventional computers. This in turn makes quantum computers extremely powerful. Several DLR institutes are already working with quantum technologies. Looking ahead, there is also a great need at DLR to conduct research on and with quantum computers.

Charged atoms cannot escape from an ion trap, as they are confined by an electromagnetic field. A laser, radio waves or microwaves can then change the state of the charged atoms (ions) in a targeted way, so that they become qubits, the building blocks of quantum computers.

Start-ups and companies are developing quantum computers based on ion traps

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.