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
Researchers used interference patterns from a laser to measure time
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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 …