A self-interfering clock as a "which path" witness

Yair Margalit, Zhifan Zhou, Shimon Machluf, Daniel Rohrlich, Yonathan Japha, Ron Folman

Research output: Contribution to journalArticlepeer-review

53 Scopus citations

Abstract

In Einstein's general theory of relativity, time depends locally on gravity; in standard quantum theory, time is global - all clocks "tick" uniformly. We demonstrate a new tool for investigating time in the overlap of these two theories: a self-interfering clock, comprising two atomic spin states. We prepare the clock in a spatial superposition of quantum wave packets, which evolve coherently along two paths into a stable interference pattern. If we make the clock wave packets "tick" at different rates, to simulate a gravitational time lag, the clock time along each path yields "which path" information, degrading the pattern's visibility. In contrast, in standard interferometry, time cannot yield "which path" information. This proof-of-principle experiment may have implications for the study of time and general relativity and their impact on fundamental effects such as decoherence and the emergence of a classical world.

Original languageEnglish
Pages (from-to)1205-1208
Number of pages4
JournalScience
Volume349
Issue number6253
DOIs
StatePublished - 11 Sep 2015

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