quantum computers tagged posts

43Ca+ qubit states and Raman transitions used for sideband cooling, single-qubit and two-qubit gates. Credit: arxiv.org/abs/1512.04600

The team achieved the logic gate, which places 2 atoms in a state of quantum entanglement and is the fundamental building block of quantum computing, with a precision (or fidelity) substantially greater than the previous world record. Quantum entanglement—a phenomenon described by Einstein as ‘spooky’ but which is at the heart of quantum technologies—occurs when 2 particles stay connected, such that an action on one affects the other, even when they are separated by great distances

The precision of the gate is a measure of how well quantum entanglement works: in our case, 99...

This is Tim Burgess with a silicon wafer on which nanostructures are grown. Credit: Stuart Hay, ANU

This will help in development of low-cost biomedical sensors, quantum computing, and a faster internet. Researcher Tim Burgess added atoms of zinc to lasers 1/100 the diameter of a human hair and made of gallium arsenide – a material used extensively in smartphones and other electronic devices. The impurities led to a 100X improvement in the amount of light from the lasers.

“Normally you wouldn’t even bother looking for light from nanocrystals of gallium arsenide – we were initially adding zinc simply to improve the electrical conductivity,” said Mr Burgess, a PhD student, ANU. “It was only when I happened to check for light emission that I realised we were onto something.”

Gallium arsenide ...

An ORNL-led research team used neutrons (depicted as spheres) to determine the magnetic structure (seen as blue arrows) of an osmium-based material. X-rays (seen as purple waves) revealed the presence of a strong spin orbit effect (illustrated in red). Credit: ORNL/Jill Hemman

An elusive massless particle could exist in a magnetic crystal structure, revealed by neutron and X-ray research. The team studied a material containing the dense element osmium and documented 2 conditions required for the presence of Weyl fermions -predicted in 1929 and observed experimentally in 2015. Researchers are looking for other materials that could host them to harness their unique properties in spintronics and advanced computing applications such as quantum computers.

“Once you have a material that hosts th...

Artistic impression of the sample, the pulse sequence, and the density matrix. Credit: Image by Antti Paraoanu

A superconducting qubit is an artificial atom fabricated on a silicon chip as an electrical circuit made of capacitors and tunnel junctions. This technology is one of the most promising for the realization of quantum computers.

In the experiment, the circuit was operated in a regime where it no longer absorbs or emits electromagnetic waves of certain frequency, as if it would be hiding under an invisibility cloak – hence the term “dark state.” Then, by using a sequence of microwave pulses, the team employed the dark state to realize a transfer of population from the ground energy level to the second energy level, without populating the first energy level...