A new way to make quantum measurements

Blind billiards

Physicists have been trying to unravel the laws which quantum particles follow, but they seem to bow down to none. Quantum mechanics goes against the most basic principles of classic physics, so much so that even Einstein himself referred to quantum entanglement as “spooky action at a distance.” More than a century of attempts to understand particles and we’re still left with probabilities instead of certainties.

German physicist Werner Heisenberg’s uncertainty principle states that precisely measuring an atom’s location, even with something as gentle as light, is impossible because everything (including light) has a momentum, and would move the atoms around upon contact. When scientists identify atomic locations, what they get are measurements of where they moved the atoms to instead of where the atoms originally were.

Dealing with atoms in an entangled state makes quantum measurements inaccurate on an even larger scale. In this strange phenomenon, one particle is linked to another regardless of distance and moving one affects the other particle instantly and directly.

A way around it

Physicists led by T. J. Elliott from the University of Oxford in the UK were able to gather basic information about the main group of atoms, such as the density of atoms and their proximity to one another while entangled, without messing up the entanglement. Their research, published in Physical Review A, showed that by measuring not the atoms themselves, but the outliers’ behavior, they can obtain a better understanding of the density of atoms in a less intrusive, less destructive manner.

This is also considered a breakthrough because physicists can now see what atoms are doing, instead of only seeing what they did. Simulations show the new method is applicable to a wide range of entangled quantum systems, and can be modified to measure other properties such as magnetization of entangled atoms, opening the possibility to better understand particle behavior.