Quantum stopwatch stores time in a quantum memory

Physicists have developed a "quantum stopwatch"--a method that stores time (in the form of states of quantum clocks) in a quantum memory. In doing so, the method avoids the accumulation of errors that usually occurs when measuring the duration of a sequence of events. In this way, the quantum stopwatch increases the accuracy of measuring time at the quantum level, which is essential for applications such as GPS, astronomy research, and distributed computing.