Quantum watch is a ‘completely new way of measuring time’

A quantum stopwatch made of lasers and helium atoms can measure the time that has passed with complete accuracy, without counting seconds like other clocks

Physics 24 October 2022

Experiment in photonic laboratory with laser

Researchers used interference patterns from a laser to measure time


A quantum watch can tell time without counting it. This stopwatch-like method of observing quantum experiments is a deceptively simple – and always accurate – way to measure the passage of time.

Marta Berholts at Uppsala University in Sweden and her colleagues based the clock on a type of experiment called a pump-probe experiment. In these tests, a “pump” laser pulse is sent into a cloud of atoms, raising them to higher energy levels, and then another, less powerful “probe” pulse is …

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