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Interfacial superconductivity and the quantum anomalous Hall effect have been developed by layer-by-layer material fabrication.

A new method created by Pritzker School of Molecular Engineering (PME) researchers can help determine the origin of electronic states in designed materials.

Assistant Professor Shuolong Yang and his colleagues created a method for better understanding magnetic topological insulators, which have unique surface properties that could make them useful in quantum information science technologies.

A giant orbital magnetic moment exists in graphene quantum dots, according to new work by physicists at the University of California Santa Cruz in the US. As well as being of fundamental interest for studying systems with relativistic electrons – that is those travelling at near-light speeds – the work could be important for quantum information science since these moments could encode information.

Graphene, a sheet of carbon just one atom thick, has a number of unique electronic properties, many of which arise from the fact that it is a semiconductor with a zero-energy gap between its valence and conduction bands. Near where the two bands meet, the relationship between the energy and momentum of charge carriers (electrons and holes) in the material is described by the Dirac equation and resembles that of a photon, which is massless.

These bands, called Dirac cones, enable the charge carriers to travel through graphene at extremely high, “ultra-relativistic” speeds approaching that of light. This extremely high mobility means that graphene-based electronic devices such as transistors could be faster than any that exist today.

Graphene is found to exhibit a magnetoresistance dwarfing that of all known materials at room temperature—a behavior that may lead to new magnetic sensors and help decipher the physics of strange metals.

One might expect that, two decades after its discovery, graphene would have exhausted its potential for surprises. But the thinnest, strongest, most conductive of all materials has now added another record to its tally. A collaboration that includes graphene’s codiscoverer and Nobel laureate Andre Geim of the University of Manchester, UK, reports that graphene can have a room-temperature magnetoresistance—a magnetic-field-induced change in electrical resistivity—that’s 100 times larger than that of any known material [1]. Graphene’s giant magnetoresistance could lead to novel magnetic-field sensors but also offer an experimental window into exotic quantum regimes of electrical conduction that might be related to the mysterious “strange metals.”

Magnetoresistance, which occurs both in bulk materials and multilayer structures, found a killer app in magnetic-field sensors such as those used to read data from magnetic memories. Researchers have long been interested in the limits of this phenomenon, which has led to discoveries of “giant,” “colossal,” and “extraordinary” forms of magnetoresistance. The associated materials exhibit resistivity changes of up to 1,000,000% when exposed to magnetic fields of several teslas (T). The largest effects, however, require extremely low temperatures that can only be reached with impractical liquid-helium cooling systems.

Even if you are not a quantum physicist, you will most likely have heard of Schrödinger’s famous cat. Erwin Schrödinger came up with the feline that can be alive and dead at the same time in a thought experiment in 1935. The obvious contradiction—after all, in everyday life we only ever see cats that are either alive or dead—has prompted scientists to try to realize analogous situations in the laboratory. So far, they have managed to do so using, for instance, atoms or molecules in quantum mechanical superposition states of being in two places at the same time.

At ETH, a team of researchers led by Yiwen Chu, professor at the Laboratory for Solid State Physics, has now created a substantially heavier Schrödinger cat by putting a small crystal into a superposition of two oscillation states. Their results, which have been published this week in the journal Science, could lead to more robust quantum bits and shed light on the mystery of why quantum superpositions are not observed in the macroscopic world.

In Schrödinger’s original thought experiment, a cat is locked up inside a metal box together with a radioactive substance, a Geiger counter and a flask of poison. In a certain time-frame—an hour, say—an atom in the substance may or may not decay through a quantum mechanical process with a certain probability, and the decay products might cause the Geiger counter to go off and trigger a mechanism that smashes the flask containing the poison, which would eventually kill the cat.

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 traveling 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.

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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.

Year 2021 😗😁

Researchers say algorithms can simulate an infinite quantum system on finite quantum computers in interesting advance for quantum tech.

So-called “higher symmetries” are illuminating everything from particle decays to the behavior of complex quantum systems.