Quantum measurement precision approaches Heisenberg limit

From PhysOrg.com:

Now, using techniques from machine learning, physicists Alexander Hentschel and Barry Sanders from the University of Calgary have recently shown how to generate measurement procedures that can outperform the best previous strategy in achieving highly precise quantum measurements. The new level of precision approaches the Heisenberg limit, which is an important goal of quantum measurement. Such quantum-enhanced measurements are useful in several areas, such as atomic clocks, gravitational wave detection, and measuring the optical properties of materials.

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Atom interferometer provides most precise test yet of Einstein's gravitational redshift

From PhysOrg.com:

While airplane and rocket experiments have proved that gravity makes clocks tick more slowly - a central prediction of Albert Einstein's general theory of relativity - a new experiment in an atom interferometer measures this slowdown 10,000 times more accurately than before, and finds it to be exactly what Einstein predicted.

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'Quantum Logic Clock' Based on Aluminum Ion is Now World's Most Precise Clock

From PhysOrg.com:

Physicists at the National Institute of Standards and Technology have built an enhanced version of an experimental atomic clock based on a single aluminum atom that is now the world’s most precise clock, more than twice as precise as the previous pacesetter based on a mercury atom.

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A better definition for the kilogram? Scientists propose a precise number of carbon atoms

A better definition for the kilogram? Scientists propose a precise number of carbon atoms from PhysOrg.com

How much is a kilogram? It turns out that nobody can say for sure, at least not in a way that won’t change ever so slightly over time. The official kilogram – a cylinder cast 118 years ago from platinum and iridium and known as the International Prototype Kilogram or “Le Gran K” – has been losing mass, about 50 micrograms at last check. The change is occurring despite careful storage at a facility near Paris.

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