quantum_mechanics (22)

Quantum Robustness...

A study demonstrates that a combination of two materials, aluminum and indium arsenide, forming a device called a Josephson junction could make quantum bits more resilient. Credit: University of Copenhagen image/Antonio Fornieri

 

Topics: Computer Science, Quantum Computing, Quantum Mechanics


Researchers have been trying for many years to build a quantum computer that industry could scale up, but the building blocks of quantum computing, qubits, still aren't robust enough to handle the noisy environment of what would be a quantum computer.

A theory developed only two years ago proposed a way to make qubits more resilient through combining a semiconductor, indium arsenide, with a superconductor, aluminum, into a planar device. Now, this theory has received experimental support in a device that could also aid the scaling of qubits.

This semiconductor-superconductor combination creates a state of "topological superconductivity," which would protect against even slight changes in a qubit's environment that interfere with its quantum nature, a renowned problem called "decoherence."

The device is potentially scalable because of its flat "planar" surface – a platform that industry already uses in the form of silicon wafers for building classical microprocessors.

The work, published in Nature, was led by the Microsoft Quantum lab at the University of Copenhagen's Niels Bohr Institute, which fabricated and measured the device. The Microsoft Quantum lab at Purdue University grew the semiconductor-superconductor heterostructure using a technique called molecular beam epitaxy, and performed initial characterization measurements.

 

New robust device may scale up quantum tech, researchers say, Kayla Wiles, Purdue University

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Super State...

Super state: three independent groups have caught sight of supersolidity. (Courtesy: iStock/3quarks)

 

Topics: Bose-Einstein Condensate, Condensed Matter Physics, Electromagnetism, Quantum Mechanics


Atomic systems that behave very much like supersolids have been created independently by teams of physicists in Italy, Germany have Austria. The teams have shown that dipolar quantum gases trapped by magnetic fields can spontaneously separate into arrays of coherent droplets, providing a system closer to the original conception of a supersolid.


The supersolid phase is a counterintuitive quantum state of matter that has both crystalline order and frictionless flow at very low temperatures. The phenomenon is related to superfluidity and was predicted 50 years ago by Soviet physicists Alexander Andreev and Ilya Lifschitz. However, supersolidity has proved frustratingly difficult to observe.

In a superfluid, the energy required to create a density modulation generally increases as the modulation’s wavelength gets shorter. At one characteristic wavelength, however, the energy takes a sudden dip – much as waves pass more easily through a crystal when the wavelength equals the separation between the atoms. If the superfluid were cold enough, Andreev and Lifschitz reasoned, the energy required would drop to zero at this wavelength. The superfluid would then spontaneously separate into tiny droplets, effectively forming an ordered crystal.

 

Supersolid behavior spotted in dipolar quantum gases, Tim Wogan, Physics World

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