Time as a “which-path” witness
Abstract: In Einstein's general theory of relativity, time depends locally on gravity; in standard quantum theory, time is global - all clocks “tick” uniformly. In my talk I will present our demonstration of 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. By 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. Time permitting, I will also present preliminary results regarding Stern-Gerlach interferometry and the emergence of time-irreversibility.
Host: Trey Porto: X50854 and Bill Phillips X 57653