quantum entanglement tagged posts

The tiny YbMgGaO4 crystal, here perched on a stand for testing, appears to be the next extremely rare material to produce an equally as rare observable quantum spin liquid. Credit: Georgia Tech / Martin Mourigal

Inside a new exotic crystal, physicist Martin Mourigal has observed strong indications of “spooky” action, and lots of it. The results of his experiments, if corroborated over time, would mean that the type of crystal is a rare new material that can produce an observable quantum spin liquid. Currently, only a small handful of materials are believed to possibly have these properties. This new crystal was synthesized for the first time only a year ago.

A “liquid” found inside a solid object may sound confusing to many people...

Ghost imaging ANU. Credit: ANU

ANU physicists have used ‘ghost imaging’ technique to create an image of an object from atoms that never interact with it. This is the first time that ghost imaging has been achieved using atoms, although it has previously been demonstrated with light, leading to applications being developed for imaging and remote sensing through turbulent environments.The atom-based result may lead to a new method for quality control of nanoscale manufacturing, including atomic scale 3D printing.

A/Professor Andrew Truscott said the experiment relied on correlated pairs of atoms. The pairs were separated by ~6cm and used to generate an image of the ANU logo. “One atom in each pair was directed towards a mask with the letters ‘ANU’ cut-out…...

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...

Some measurements of entanglement violate monogamy, yet are geometrically faithful; others are monogamous but not faithful. Credit: Lancien et al. ©2016 American Physical Society

As expected, “monogamous” and “faithful” mean something a little different in the quantum world than they do in everyday language. When quantified by standard means, entanglement cannot be both monogamous and faithful at the same time. The results may be relevant when assessing the security of quantum cryptographic schemes, which rely on the monogamy of entanglement, and may also help to better understand the long-standing “firewall debate” related to the behavior of black holes.

Monogamy is considered to be a defining property of entanglement. Eg...