What is time, exactly, and how can we keep track of it? As strange as it may seem, physicists are still looking for precise answers to these questions. In quantum mechanics, time plays a different role from other quantities such as position, energy and momentum, as it is not an observable that can be measured directly. Moreover, the equations of quantum mechanics do not single out a preferred direction of time. How can one then rely on the laws of quantum mechanics to keep track of time?
An international collaboration including ICTP postdoctoral fellow Ludmila Viotti and ICTP senior research scientist Rosario Fazio might have just found a route to answering this question by proposing a protocol to build a high-precision clock that exploits the properties of quantum mechanics. In an article published in Physical Review Letters, they suggest that the properties of time crystals, a new quantum phase of matter recently predicted and experimentally explored, could be used for timekeeping.
