Computers Math

Mechanically responsive molecular crystals are extremely useful in soft robotics, which requires a versatile actuation technology. Crystals driven by the photothermal effect are particularly promising for achieving high-speed actuation. However, the response (bending) observed in these crystals is usually small. Now, scientists from Japan address this issue by inducing large resonated natural vibrations in anisole crystals with UV light illumination at the natural vibration frequency of the crystal.
Every material possesses a unique natural vibration frequency such that when an external periodic force is applied to this material close to this frequency, the vibrations are greatly amplified. In the parlance of physics, this phenomenon is known as “resonance.” Resonance is ubiquitous in our daily life, and, depending on the context, could be deemed desirable or undesirable. For instance, musical instruments like the guitar relies on resonance for sound amplification. On the other hand, buildings and bridges are more likely to collapse under an earthquake if the ground vibration frequency matches their natural frequency.
Interestingly, natural vibration has not received much attention in material actuation, which relies on the action of mechanically responsive crystals. Versatile actuation technologies are highly desirable in the field of soft robotics. Although crystal actuation based on processes like photoisomerisation and phase transitions have been widely studied, these processes lack versatility since they require specific crystals to work. One way to improve versatility is by employing photothermal crystals, which show bending due to light-induced heating. While promising for achieving high-speed actuation, the bending angle is usually small ( More

In the world of computing, we typically think of information as being stored as ones and zeros — also known as binary encoding. However, in our daily life we use ten digits to represent all possible numbers. In binary the number 9 is written as 1001 for example, requiring three additional digits to represent the same thing.
The quantum computers of today grew out of this binary paradigm, but in fact the physical systems that encode their quantum bits (qubit) often have the potential to also encode quantum digits (qudits), as recently demonstrated by a team led by Martin Ringbauer at the Department of Experimental Physics at the University of Innsbruck. According to experimental physicist Pavel Hrmo at ETH Zurich: “The challenge for qudit-based quantum computers has been to efficiently create entanglement between the high-dimensional information carriers.”
In a study published in the journal Nature Communications the team at the University of Innsbruck now reports, how two qudits can be fully entangled with each other with unprecedented performance, paving the way for more efficient and powerful quantum computers.
Thinking like a quantum computer
The example of the number 9 shows that, while humans are able calculate 9 x 9 = 81 in one single step, a classical computer (or calculator) has to take 1001 x 1001 and perform many steps of binary multiplication behind the scenes before it is able to display 81 on the screen. Classically, we can afford to do this, but in the quantum world where computations are inherently sensitive to noise and external disturbances, we need to reduce the number of operations required to make the most of available quantum computers.
Crucial to any calculation on a quantum computer is quantum entanglement. Entanglement is one of the unique quantum features that underpin the potential for quantum to greatly outperform classical computers in certain tasks. Yet, exploiting this potential requires the generation of robust and accurate higher-dimensional entanglement.
The natural language of quantum systems
The researchers at the University of Innsbruck were now able to fully entangle two qudits, each encoded in up to 5 states of individual Calcium ions. This gives both theoretical and experimental physicists a new tool to move beyond binary information processing, which could lead to faster and more robust quantum computers.
Martin Ringbauer explains: “Quantum systems have many available states waiting to be used for quantum computing, rather than limiting them to work with qubits.” Many of today’s most challenging problems, in fields as diverse as chemistry, physics or optimisation, can benefit from this more natural language of quantum computing.
The research was financially supported by the Austrian Science Fund FWF, the Austrian Research Promotion Agency FFG, the European Research Council ERC, the European Union and the Federation of Austrian Industries Tyrol, among others. More

There are high expectations that quantum computers may deliver revolutionary new possibilities for simulating chemical processes. This could have a major impact on everything from the development of new pharmaceuticals to new materials. Researchers at Chalmers University have now, for the first time in Sweden, used a quantum computer to undertake calculations within a real-life case in chemistry.
“Quantum computers could in theory be used to handle cases where electrons and atomic nuclei move in more complicated ways. If we can learn to utilise their full potential, we should be able to advance the boundaries of what is possible to calculate and understand,” says Martin Rahm, Associate Professor in Theoretical Chemistry at the Department of Chemistry and Chemical Engineering, who has led the study.
Within the field of quantum chemistry, the laws of quantum mechanics are used to understand which chemical reactions are possible, which structures and materials can be developed, and what characteristics they have. Such studies are normally undertaken with the help of super computers, built with conventional logical circuits. There is however a limit for which calculations conventional computers can handle. Because the laws of quantum mechanics describe the behaviour of nature on a subatomic level, many researchers believe that a quantum computer should be better equipped to perform molecular calculations than a conventional computer.
“Most things in this world are inherently chemical. For example, our energy carriers, within biology as well as in old or new cars, are made up of electrons and atomic nuclei arranged in different ways in molecules and materials. Some of the problems we solve in the field of quantum chemistry are to calculate which of these arrangements are more likely or advantageous, along with their characteristics,” says Martin Rahm.
A new method minimises errors in the quantum chemical calculations
There is still a way to go before quantum computers can achieve what the researchers are aiming for. This field of research is still young and the small model calculations that are run are complicated by noise from the quantum computer’s surroundings. However, Martin Rahm and his colleagues have now found a method that they see as an important step forward. The method is called Reference-State Error Mitigation (REM) and works by correcting for the errors that occur due to noise by utilising the calculations from both a quantum computer and a conventional computer.

“The study is a proof-of-concept that our method can improve the quality of quantum-chemical calculations. It is a useful tool that we will use to improve our calculations on quantum computers moving forward,” says Martin Rahm.
The principle behind the method is to first consider a reference state by describing and solving the same problem on both a conventional and a quantum computer. This reference state represents a simpler description of a molecule than the original problem intended to be solved by the quantum computer. A conventional computer can solve this simpler version of the problem quickly. By comparing the results from both computers, an exact estimate can be made for the amount of error caused by noise. The difference between the two computers’ solutions for the reference problem can then be used to correct the solution for the original, more complex, problem when it is run on the quantum processor. By combining this new method with data from Chalmers’ quantum computer Särimner* the researchers have succeeded in calculating the intrinsic energy of small example molecules such as hydrogen and lithium hydride. Equivalent calculations can be carried out more quickly on a conventional computer, but the new method represents an important development and is the first demonstration of a quantum chemical calculation on a quantum computer in Sweden.
“We see good possibilities for further development of the method to allow calculations of larger and more complex molecules, when the next generation of quantum computers are ready,” says Martin Rahm.
Quantum computer built at Chalmers
The research has been conducted in close collaboration with colleagues at the Department of Microtechnology and Nanoscience. They have built the quantum computers that are used in the study, and helped perform the sensitive measurements that are needed for the chemical calculations.

“It is only by using real quantum algorithms that we can understand how our hardware really works and how we can improve it. Chemical calculations are one of the first areas where we believe that quantum computers will be useful, so our collaboration with Martin Rahm’s group is especially valuable,” says Jonas Bylander, Associate Professor in Quantum Technology at the Department of Microtechnology and Nanoscience.
More about the research
Read the article Reference-State Error Mitigation: A Strategy for High Accuracy Quantum Computation of Chemistry in the Journal of Chemical Theory and Computation.
The article is written by Phalgun Lolur, Mårten Skogh, Werner Dobrautz, Christopher Warren, Janka Biznárová, Amr Osman, Giovanna Tancredi, Göran Wendin, Jonas Bylander, and Martin Rahm. The researchers are active at Chalmers University of Technology.
The research has been conducted in cooperation with the Wallenberg Centre for Quantum Technology (WACQT) and the EU-project OpensuperQ. OpensuperQ connects universities and companies in 10 European countries with the aim of building a quantum computer, and its extension will contribute further funding to researchers at Chalmers for their work with quantum chemical calculations.
*Särimner is the name of a quantum processor with five qubits, or quantum bits, built by Chalmers within the framework of the Wallenberg Center for Quantum Technology (WACQT). Its name is borrowed from Nordic mythology, in which the pig Särimner was butchered and eaten every day, only to be resurrected. Särimner has now been replaced by a larger computer with 25 qubits and the goal for WACQT is to build a quantum computer with 100 qubits that can solve problems far beyond the capacity of today’s best conventional super-computers. More

5G communications’ superfast download speeds rely on the high frequencies that drive the transmissions. But the highest frequencies come with a tradeoff.
Frequencies at the upper end of the 5G spectrum hold the greatest amount of data and could be critical to high-resolution augmented and virtual reality, video streaming, video conferencing, and services in crowded urban areas. But those high-end frequencies are easily blocked by walls, furniture and even people. This has been a hurdle to achieving the technology’s full potential.
Now, a team led by Princeton researchers has developed a new device to help higher-frequency 5G signals, known as millimeter-wave or mmWave, overcome this obstacle. The device, called mmWall, is about the size of a small tablet. It can steer mmWave signals to reach all corners of a large room, and, when installed in a window, can bring signals from an outdoor transmitter indoors. The researchers presented their work on mmWall at the USENIX Symposium on Networked Systems Design and Implementation in Boston on April 19.
While computers and smartphones often connect to Wi-Fi indoors to get the best data speeds, outdoor 5G base stations could someday replace Wi-Fi systems and provide high-speed connectivity both indoors and outdoors, preventing glitches when devices switch between networks, said Kun Woo Cho, a Ph.D. student in Princeton’s Department of Computer Science and the lead author of the research. Boosting 5G signals with technology like mmWall will be crucial to this broader adoption, she said.
The mmWall is an accordion-like array of 76 vertical panels that can both reflect and refract radio waves at frequencies above 24 gigahertz, the lower bound of mmWave signals. These frequencies can provide a bandwidth five to 10 times greater than the maximum capability of 4G networks. The device can steer beams around obstacles, as well as efficiently align the beams of transmitter and receiver to establish connections quickly and maintain them seamlessly.
“Wireless transmissions at these higher frequencies resemble beams of light more than a broadcast in all directions, and so get blocked easily by humans and other obstacles,” said senior study author Kyle Jamieson, a professor of computer science who leads the Princeton Advanced Wireless Systems Lab (PAWS).
The mmWall surface is the first to be able to reflect such transmissions in such a way that the angle of reflection does not equal the angle of incidence, sidestepping a classic law of physics. The device can also “refract transmissions that hit one side of the surface through at a different angle of departure, and is fully electronically reconfigurable within microseconds, allowing it to keep up with the ‘line rate’ of tomorrow’s ultra-fast networks,” said Jamieson.
Each panel of mmWall holds two meandering lines of thin copper wire, flanking a line of 28 broken circles made of thicker wire, which constitute meta-atoms — materials whose geometry is designed to achieve tunable electrical and magnetic properties. Applying controlled electrical current to these meta-atoms can change the behavior of the mmWave signals that interact with the mmWall surface — dynamically steering the signals around obstacles by shifting their paths by up to 135 degrees.
“Just by changing the voltage, we can tune the phase,” or the relationship between the incoming and outgoing radio waves, said Cho. “We can basically steer to any angle for transmission and reflection. State-of-the-art surfaces generally only work for reflection or only work for transmission, but with this we can do both at any arbitrary angle with high amplitude.”
The process is analogous to light waves slowing down when they pass through a glass of water, said Cho. The water changes the direction of the light waves and makes objects appear distorted when viewed through the water.
Cho mathematically analyzed different parameters of the meta-atoms’ geometry to arrive at the optimal size, shape and arrangement for the copper meta-atoms and the pathways between them, which were fabricated with standard printed circuit board technology and mounted on a 3D-printed frame. In designing mmWall, the team aimed to use the smallest possible meta-atoms (each has a diameter of less than a millimeter), in order to optimize their interaction with mmWaves, as well as to simplify the device’s fabrication and minimize the amount of copper. The mmWall also uses only microwatts of electricity, about 1,000 times less than Wi-Fi routers which use an average of about 6 watts.
Cho tested mmWall’s ability to transmit and steer mmWave signals in a 900-square-foot lab in Princeton’s Computer Science building. With a transmitter in the room, mmWall improved the signal-to-noise ratio at nearly all of the 23 spots tested around the room. And when the transmitter was placed outdoors, mmWall again boosted signals all around the room, including in roughly 40% of spots that had been completely blocked without the use of mmWall. More

In the future, communications networks and computers will use information stored in objects governed by the microscopic laws of quantum mechanics. This capability can potentially underpin communication with greatly enhanced security and computers with unprecedented power. A vital component of these technologies will be memory devices capable of storing quantum information to be retrieved at will.
Virginia Lorenz, a professor of physics at the University of Illinois Urbana-Champaign, studies Lambda-type optical quantum memory devices, a promising technology that relies on light interacting with a large group of atoms. She is developing a device based on hot metallic vapor with graduate student Kai Shinbrough. As the researchers work towards a practical device, they are also providing some of the first theoretical analyses of Lambda-type devices. Most recently, they reported the first variance-based sensitivity analysis describing the effects of experimental noise and imperfections in Physical Review A.
“Prior to this paper, you would just have to assume that everything in the quantum memory behaves ideally,” Shinbrough said. “This is the first time that things like noise have been considered, and the results of our analyses inform experimental design.”
Lambda-type quantum memory uses a collection of atoms that interacts with two kinds of light: single photons containing quantum information that are absorbed, and powerful laser pulses controlling when the photons’ information is absorbed and released. There are several storage-and-retrieval protocols that rely on different mechanisms, and the best choice is determined by the properties of the atoms and the controlling laser pulses.
Past analyses of these protocols assumed ideal conditions. Effects like device noise and small errors in experimental settings were not discussed. Shinbrough and Lorenz needed to understand these effects to develop a robust quantum memory device, so they filled this gap in the literature. They analyzed the impact of both random device noise and slow overall drift in experimental parameters on a Lambda-type device’s memory efficiency, a measure of how often the device works as intended.
“The techniques we used are well established in classical physics and engineering, but we’re applying them to a quantum system for the first time,” Shinbrough said.
In addition to considering how noise and drift in experimental parameters individually impact device performance, the researchers used the technique of Sobol’ sensitivity analysis to study how the simultaneous variation of all parameters impacts the memory efficiency. This allowed them to identify the parameters that had the most significant impact for each protocol and determine how variations in different parameters combine.
Shinbrough explained that the central result of this analysis is understanding how different experimental parameters may be tuned to compensate for imperfections in different settings. He gave the example of variation in the arrival times of the control pulse and the single photon. Each memory mechanism relies on a carefully tuned delay in the arrival times. If this delay begins to drift, then the control pulse can be made to last longer in time so the overlap with the single photon is roughly the same and the impact on memory efficiency is mitigated.
The results of this analysis have informed Shinbrough and Lorenz’s experimental efforts. The researchers found that certain effects like variations in the hot metal vapor are often negligible while others like the characteristics of the controlling pulse can have a significant impact on experimental performance.
“Our analyses have allowed us to develop a better-informed experiment taking full advantage of our device’s properties,” Lorenz said. “Moreover, we have developed a framework that allows others to perform the same analyses for their experiments.” More

The 2022 Nobel Prize in Physics was awarded to Alain Aspect, John Clauser, and Anton Zeilinger for their works on “quantum nonlocality” in quantum mechanics. Quantum nonlocality is a phenomenon where connected particles can affect each other instantly, regardless of the distance separated.
Imagine you owned a pair of gloves. These gloves are a pair and therefore correlated in some way, no matter how far apart they are. One day, you place one of the gloves into your backpack and hop on a flight to travel to another country, while the other glove remains at home. According to quantum nonlocality, if you changed the color of the glove you brought with you, the color of the glove back home would instantaneously change too, despite being separated by a large distance.
Nonlocality violates many of the concepts predicted by classical physics, where particles’ properties are predetermined and change occurs only through direct physical interaction or fields propagated at a finite speed. Nonlocality has a wide array of implications for understanding the future of reality, quantum mechanics, and the development of quantum technologies.
There exist several ways to define and interpret nonlocality. For instance, a set of mathematical expressions called the Bell and CHSH inequalities demonstrates nonlocality by violating inequalities. Meanwhile, Lucien Hardy proposed an alternative interpretation of quantum nonlocality in 1992 when he developed the Hardy Paradox.
Suppose there are three quantities A, B, and C, where A is greater than B and B is greater than C. Intuitively, and according to a fundamental mathematical property known as the transitive property (or local hidden variable theories in physics), this would render A greater than C.
However, Hardy noted that there is still room for a situation where C is greater than A. This violates the transitive property, and such violations are possible in the quantum world when particles are entangled with each other. In other words, this is nonlocality.
We can use “rock-paper-scissors” to imagine this. While it is evident that rock beats scissors and scissors beat paper, it is impossible for the rock to beat paper. Paper beating rock does not align with any mathematical reasoning, hence why it is a paradox.
A recent study, published in the journal American Physical Review A, has made interesting revelations about the Hardy nonlocality. The study was co-authored by Dr. Le Bin Ho from Tohoku University’s Frontier Research Institute for Interdisciplinary Sciences (FRIS).
“The Hardy nonlocality has significant implications for understanding fundamental quantum mechanics, and it is vital for strengthening the probability of nonlocal,” said Le. “We used quantum computers and methods to investigate the measurement of Hardy nonlocality to improve its probability.”
Le and his colleagues did this by proposing a theoretical framework for attaining a higher nonlocal probability. They verified this by using a theoretical model and a quantum simulation.
Despite previous studies showing the opposite, they discovered that nonlocal probability increases as the number of particles grows. This suggests that quantum effects persist even at larger scales, further challenging classical theories of physics.
Le says these findings have important ramifications for understanding quantum mechanics and its potential applications in communications. “Understanding quantum nonlocality can lead to groundbreaking technological advancements, such as the secure transmission of information through quantum communication via nonlocality resources.” More

Quantum teleportation is a technique allowing the transfer of quantum information between two distant quantum objects, a sender and a receiver, using a phenomenon called quantum entanglement as a resource. The unique feature of this process is that the actual information is not transferred by sending quantum bits (qubits) through a communication channel connecting the two parties; instead, the information is destroyed at one location and appears at the other one without physically travelling between the two. This surprising property is enabled by quantum entanglement, accompanied by the transmission of classical bits.
There is a deep interest in quantum teleportation nowadays within the field of quantum communications and quantum networks because it would allow the transfer of quantum bits between network nodes over very long distances, using previously shared entanglement. This would help the integration of quantum technologies into current telecommunication networks and extend the ultra-secure communications enabled by these systems to very long distances. In addition, quantum teleportation permits the transfer of quantum information between different kinds of quantum systems, e.g. between light and matter or between different kinds of quantum nodes.
Quantum teleportation was theoretically proposed in the early 90s and experimental demonstrations were carried out by several groups around the world. While the scientific community has gained extensive experience on how to perform these experiments, there is still an open question on how to teleport information in a practical way, allowing reliable and fast quantum communication over an extended network. It seems clear that such an infrastructure should be compatible with the current telecommunications network. In addition, the protocol of quantum teleportation requires a final operation to be applied on the teleported qubit, conditioned on the result of the teleportation measurement (transmitted by classical bits), in order to transfer the information faithfully and at a higher rate, a feature called active feed-forward. This means that the receiver requires a device known as a quantum memory that can store the qubit without degrading it until the final operation can be implemented. Finally, this quantum memory should be able to operate in a multiplexed fashion to maximize the speed of teleporting information when the sender and the receiver are far away. To date, no implementation had incorporated these three requirements in the same demonstration.
In a recent study published in Nature Communications, ICFO researchers Dario Lago-Rivera, Jelena V. Rakonjac, Samuele Grandi, led by ICREA Prof. at ICFO Hugues de Riedmatten have reported achieving long distance teleportation of quantum information from a photon to a solid-state qubit, a photon stored in a multiplexed quantum memory. The technique involved the use of an active feed-forward scheme, which, together with the multimodality of the memory, has allowed maximization of the teleportation rate. The proposed architecture was compatible with the telecommunications channels, and thus enabling future integration and scalability for long-distance quantum communication.
How to achieve quantum teleportation
The team built two experimental setups, that in the jargon of the community are usually called Alice and Bob. The two setups were connected by a 1km optical fiber spun up in a spool, to emulate a physical distance between the parties.

Three photons were involved in the experiment. In the first setup, Alice, the team used a special crystal to create two entangled photons: the first photon at 606 nm, called signal photon, and the second photon called idler photon, compatible with the telecommunications infrastructure. Once created, “we kept the first 606 nm photon at Alice and stored it in a multiplexed solid-state quantum memory, holding it in the memory for future processing. At the same time, we took the telecom photon created at Alice and sent it through the 1km of optical fiber to reach the second experimental setup, called Bob,” Dario Lago recalls.
In this second setup, Bob, the scientists had another crystal where they created a third photon, where they had encoded the quantum bit they wanted to teleport. Once the third photon was created, the second photon had arrived to Bob from Alice, and this is where the core of the teleportation experiment takes place.
Teleporting information over 1km
The second and third photons interfered with each other through what is known as a Bell State measurement (BSM). The effect of this measurement was to mix the state of the second and third photon. Thanks to the fact that the first and second photons were entangled to begin with, i.e. their joint state was highly correlated, the result of the BSM was that of transferring the information encoded in the third photon to the first one, stored by Alice in the quantum memory, 1 km away. As Dario Lago and Jelena Rakonjac mention, “we are capable of transferring information between two photons that were never in contact before, but connected through a third photon that was indeed entangled with the first. The uniqueness of this experiment lies in the fact that we employed a multiplexed quantum memory capable of storing the first photon for long enough such that by the time Alice found out that the interaction had happened, we were still able to process the teleported information as the protocol requires.”
This processing that Dario and Jelena mention was the active feed-forward technique mentioned earlier. Depending on the outcome of the BSM, a phase-shift was applied to the first photon after storage in the memory. In this way, the same state would always be encoded in the first photon. Without this, half of the teleportation events would have to be discarded. Moreover, the multimodality of the quantum memory allowed them to increase the teleportation rate beyond the limits imposed by the 1 km separation between them without degrading the quality of the teleported qubit. Overall, this resulted in a teleportation rate three times higher than for a single-mode quantum memory, only limited by the speed of the classical hardware.
Scalability and Integration
The experiment carried out by this group in 2021, where they achieved for the first time entanglement of two multimode quantum memories separated by 10 meters and heralded by a photon at the telecommunication wavelength, has been the precursor of this experiment.
As Hugues de Riedmatten emphasizes, “Quantum teleportation will be crucial for enabling high-quality long-distance communication for the future quantum internet. Our goal is to implement quantum teleportation in more and more complex networks, with previously distributed entanglement. The solid-state and multiplexed nature of our quantum nodes as well as their compatibility with the telecom network make them a promising approach to deploy the technology over long distance in the installed fiber network.”
Further improvements are already being planned. On the one hand, the team is focused on developing and improving the technology in order to extend the setup to much longer distances while maintaining the efficiency and rates. On the other hand, they also aim at studying and using this technique in the transfer of information between different types of quantum nodes, for a future quantum Internet that will be able to distribute and process quantum information between remote parties. More

A team of UCR electrical engineers and material scientists demonstrated a research breakthrough that may result in wide-ranging advancements in electrical, optical, and computer technologies.
The Marlan and Rosemary Bourns College of Engineering research group, led by distinguished professor Alexander Balandin, has shown in the laboratory the unique and practical function of newly created materials, which they called quantum composites.
These composites consist of small crystals of called “charge density wave quantum materials” incorporated within a polymer (large molecules with repeating structures) matrix. Upon heating or light exposure, charge density wave material undergoes a phase transition that leads to an unusual electrical response of the composites.
Compared to other materials that reveal quantum phenomena, the quantum composites created by Balandin’s group exhibited functionality at a much wider range of temperatures and had a greatly increased ability to store electricity, giving them an excellent potential for utility.
The University of California, Riverside, researchers describe the unique properties in a paper titled “Quantum Composites with Charge-Density-Wave Fillers” published in the journal Advanced Materials. The lead authors of the paper are Zahra Barani and Tekwam Geremew, UCR graduate students with the college’s Department of Electrical and Computer Engineering, who synthesized and tested the composites. Another UCR graduate student Maedeh Taheri is a co-author who helped with electrical measurements. Balandin and Fariborz Kargar, an assistant adjunct professor and project scientist, are the corresponding authors.
The term quantum refers to materials and devices where electrons behave more like waves than particles. The wave nature of electrons can give materials unusual properties that are used in a new generation of computer, electronic and optic technologies.

Materials that reveal quantum phenomena are sought for building quantum computers that go beyond the limitations of most computing that is now based on chips that use binary bits for computations. Such materials are also sought for super-sensitive sensors used for various electronic and optic applications.
But the materials with quantum phenomena have major drawbacks, Balandin said.
“The problem with these materials is that the quantum phenomena are fragile and typically observed only at extremely low temperatures,” he said. “The defects and impurities destroy the electron wave function.”
Remarkably, the charge density wave material in the quantum composites created by Balandin’s lab exhibited functionality as high as 50º C above room temperature. This transition temperature is close to the temperature of the operation of computers and other electronic gadgets, which heat up when they operate. This temperature tolerance opens a possibility for a wide range of applications of quantum composites in electronics and energy storage.
The researchers also found that quantum composites have an unusually high dielectric constant – a metric that characterizes the material’s ability to store electricity. The dielectric constant of the electrically insulating composites increased by more than two orders of magnitude, which allows for smaller and more powerful capacitors used for energy storage.
“Energy storage capacitors can be found in battery-powered applications,” Balandin said. “Capacitors can be used to deliver peak power and provide energy for computer memory during an unexpected shut-off. Capacitors can charge and discharge faster compared to batteries. In order to broaden the use of capacitors for energy storage, one needs to increase the energy per volume. Our quantum composite material may help to achieve this goal.”
Another possible application for quantum composites is reflective coating. The change in the dielectric constant induced by heating, light exposure, or application of an electrical field can be used to change the light reflection from the glasses and windows coated with such composites.
“We hope that our ability to preserve the quantum condensate phases in the charge-density-wave materials even inside disordered composites and even above room temperature can become a game changer for many applications. It is a conceptually different approach for tuning the properties of composites that we use in everyday life,” Balandin added.
The team at UCR collaborated with Megan Stokey, Matthew Hilfiker, and Mathias Schubert, of the University of Nebraska, who conducted some of the optical measurements, and Nicholas Sesing and Tina Salguero of the University of Georgia, who synthesized an ingredient material used in the composite preparation at UCR. More