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Topological insulators are innovative materials that conduct electricity on the surface, but act as insulators on the inside. Physicists at the University of Basel and the Istanbul Technical University have begun investigating how they react to friction. Their experiment shows that the heat generated through friction is significantly lower than in conventional materials. This is due to a new quantum mechanism, the researchers report in the scientific journal Nature Materials.

Thanks to their unique electrical properties, topological insulators promise many innovations in the electronics and computer industries, as well as in the development of quantum computers. The thin surface layer can conduct electricity almost without resistance, resulting in less heat than traditional materials. This makes them of particular interest for electronic components.

Furthermore, in topological insulators, the electronic friction—i.e. the electron-mediated conversion of electrical energy into heat—can be reduced and controlled. Researchers of the University of Basel, the Swiss Nanoscience Institute (SNI) and the Istanbul Technical University have now been able to experimentally verify and demonstrate exactly how the transition from energy to heat through friction behaves—a process known as dissipation.

Quantum computers have the potential to someday far outperform our traditional machines, thanks to their ability to store data on “qubits” that can exist in two states at once. That sounds good in theory, but in practice it’s hard to make materials that can do that and stay stable for long periods of time. Now, researchers from Johns Hopkins University have found a superconducting material that naturally stays in two states at once, which could be an important step towards quantum computers.

Our current computers are built on the binary system. That means they store and process information as binary “bits” – a series of ones and zeroes. This system has worked well for us for the better part of a century, but the general rate of computing progress has started to slow down in recent years.

Quantum computers could turn that trend on its head. The key is the use of qubits, which can store data as either a one, a zero or both at the same time – much like Schrödinger’s famous thought experiment with the cat that’s both alive and dead at the same time. Using that extra power, quantum computers would be able to outperform traditional ones at tasks involving huge amounts of data, such as AI, weather forecasting, and drug development.

Researchers have successfully used sound waves to control quantum information in a single electron, a significant step towards efficient, robust quantum computers made from semiconductors.

The international team, including researchers from the University of Cambridge, sent high-frequency sound waves across a modified semiconductor device to direct the behaviour of a single electron, with efficiencies in excess of 99 percent. The results are reported in the journal Nature Communications.

A quantum computer would be able to solve previously unsolvable computational problems by taking advantage of the strange behaviour of particles at the subatomic scale, and quantum phenomena such as entanglement and superposition. However, precisely controlling the behaviour of quantum particles is a mammoth task.

Searching for new substances and developing new techniques in the chemical industry: tasks that are often accelerated using computer simulations of molecules or reactions. But even supercomputers quickly reach their limits. Now researchers at the Max Planck Institute of Quantum Optics in Garching (MPQ) have developed an alternative, analogue approach. An international team around Javier Argüello-Luengo, Ph.D. candidate at the Institute of Photonic Sciences (ICFO), Ignacio Cirac, Director and Head of the Theory Department at the MPQ, Peter Zoller, Director at the Institute of Quantum Optics and Quantum Information in Innsbruck (IQOQI), and others have designed the first blueprint for a quantum simulator that mimics the quantum chemistry of molecules. Like an architectural model can be used to test the statics of a future building, a molecule simulator can support investigating the properties of molecules. The results are now published in the scientific journal Nature.

Using hydrogen, the simplest of all molecules, as an example, the global team of physicists from Garching, Barcelona, Madrid, Beijing and Innsbruck theoretically demonstrate that the quantum simulator can reproduce the behaviour of a real molecule’s electron shell. In their work, they also show how experimental physicists can build such a simulator step by step. “Our results offer a new approach to the investigation of phenomena appearing in quantum chemistry,” says Javier Argüello-Luengo. This is highly interesting for chemists because classical computers notoriously struggle to simulate chemical compounds, as molecules obey the laws of quantum physics. An electron in its shell, for example, can rotate to the left and right simultaneously. In a compound of many particles, such as a molecule, the number of these parallel possibilities multiplies. Because each electron interacts with each other, the complexity quickly becomes impossible to handle.

As a way out, in 1982, the American physicist Richard Feynman suggested the following: We should simulate quantum systems by reconstructing them as simplified models in the laboratory from individual atoms, which are inherently quantum, and therefore implying a parallelism of the possibilities by default. Today, quantum simulators are already in use, for example to imitate crystals. They have a regular, three-dimensional atomic lattice which is imitated by several intersecting laser beams, the “optical lattice.” The intersection points form something like wells in an egg carton into which the atoms are filled. The interaction between the atoms can be controlled by amplifying or attenuating the rays. This way researchers gain a variable model in which they can study atomic behavior very precisely.

It’s not yet clear whether a theory that unites general relativity and quantum mechanics would permit time travel.

A new paper from researchers at the University of Chicago introduces a technique for compiling highly optimized quantum instructions that can be executed on near-term hardware. This technique is particularly well suited to a new class of variational quantum algorithms, which are promising candidates for demonstrating useful quantum speedups. The new work was enabled by uniting ideas across the stack, spanning quantum algorithms, machine learning, compilers, and device physics. The interdisciplinary research was carried out by members of the EPiQC (Enabling Practical-scale Quantum Computation) collaboration, an NSF Expedition in Computing.

Adapting to a New Paradigm for Quantum Algorithms

The original vision for quantum algorithms dates to the early 1980s, when physicist Richard Feynman proposed performing molecular simulations using just thousands of noise-less qubits (quantum bits), a practically impossible task for traditional computers. Other algorithms developed in the 1990s and 2000s demonstrated that thousands of noise-less qubits would also offer dramatic speedups for problems such as database search, integer factoring, and matrix algebra. However, despite recent advances in quantum hardware, these algorithms are still decades away from scalable realizations, because current hardware features noisy qubits.

Researchers from Aalto University and VTT Technical Research Centre of Finland have built a super-sensitive bolometer, a type of thermal radiation detector. The new radiation detector, made of a gold-palladium mixture makes it easier to measure the strength of electromagnetic radiation in real time. Bolometers are used widely in thermal cameras in the construction industry and in satellites to measure cosmic radiation.

The new developments may help bolometers find their way to quantum computers. If the new radiation detector manages to function as well in space as it does in the laboratory, it can also be used to measure cosmic microwave background radiation in space more accurately.

“The new detector is extremely sensitive, and its noise level—how much the signal bounces around the correct value, is only one tenth of the noise of any other bolometer. It is also a hundred times faster than previous low-noise radiation detectors,” says Mikko Möttönen, who works as a joint Professor of Quantum Technology at Aalto University and VTT.

Researchers at EPFL have created a metallic microdevice in which they can define and tune patterns of superconductivity. Their discovery, which holds great promise for quantum technologies of the future, has just been published in Science.

In superconductors, electrons travel with no resistance. This phenomenon currently only occurs at very low temperatures. There are many practical applications, such as magnetic resonance imaging (MRI). Future technologies, however, will harness the total synchrony of electronic behavior in superconductors—a property called the phase. There is currently a race to build the world’s first quantum computer, which will use phases to perform calculations. Conventional superconductors are very robust and hard to influence, and the challenge is to find new materials in which the superconducting state can be easily manipulated in a device.

EPFL’s Laboratory of Quantum Materials (QMAT), headed by Philip Moll, has been working on a specific group of unconventional superconductors known as heavy fermion materials. The QMAT scientists, as part of a broad international collaboration between EPFL, the Max Planck Institute for Chemical Physics of Solids, the Los Alamos National Laboratory and Cornell University, made a surprising discovery about one of these materials, CeIrIn₅.

A team of Northwestern University researchers is the first to document the role chemistry will play in next generation computing and communication. By applying their expertise to the field of Quantum Information Science (QIS), they discovered how to move quantum information on the nanoscale through quantum teleportation—an emerging topic within the field of QIS. Their findings were published in the journal, Nature Chemistry, on September 23, 2019, and have untold potential to influence future research and application.

Quantum teleportation allows for the transfer of quantum information from one location to another, in addition to a more secure delivery of that information through significantly improved encryption.

The QIS field of research has long been the domain of physicists, and only in the past decade has drawn the attention and involvement of chemists who have applied their expertise to exploit the quantum nature of molecules for QIS applications.