A quantum memory may be all scientists need to beat the limit of Heisenberg’s uncertainty principle, according to a paper published in Nature Physics. According to a group of researchers, maximally entangling a particle with a quantum memory and measuring one of the particle’s variables, like its position, should snap the quantum memory in a corresponding state, which could then be measured. This would allow them to do something long thought verboten by the laws of physics: figure out the state of certain pairs of variables at the exact same time with an unprecedented amount of certainty.
Our ability to observe particles at the quantum level is currently limited by Heisenberg’s uncertainty principle. Heisenberg noticed that when someone measured one variable of a particle, such as its position, there were some other variables, like momentum, that could not be simultaneously measured with as much precision—there was a small amount of uncertainty applied to one or both of the measurements.
The physical reasoning behind this is hard to follow. But Paul Dirac, another physicist, made up a scenario to illustrate why some variables have this contentious relationship.
Dirac pointed out that one of the only ways to measure a particle’s position is by bouncing a photon off of it, and seeing where and how that photon lands on a detector. How the photon lands completely describes the particle’s position, but by hitting it, the measurement changes the particle’s momentum.
Likewise, a measure of momentum would change the particle’s position. Because of this quirk, scientists thought it was impossible to know certain pairs of variables that affect one another at the same exact time with a very high degree of precision.
Then along came entanglement. When two particles are entangled, reading even one variable of one of the particles collapses the wavefunction of both particles, giving finite values to all related variables.
The cadre of scientists behind the current paper realized that, by using the process of entanglement, it would be possible to essentially use two particles to figure out the complete state of one. They might even be able to measure incompatible variables like position and momentum. The measurements might not be perfectly precise, but the process could allow them to beat the limit of the uncertainty principle.
Quantum memory may topple Heisenberg’s uncertainty principle.