Sub-Fourier Frequency Resolution with a Quantum Sensor
ORAL
Abstract
Resolution of the frequency components of a time-dependent signal is conventionally limited by the total measurement time. This limits spectroscopy of signals with short coherence times. Here, we demonstrate sub-Fourier resolution of the frequency components of an incoherent signal with at most two frequencies using a quantum sensor. In particular, we pick a measurement time at which the quantum sensor will be in an eigenstate if there is only one frequency and perform a measurement in that basis. Thus, we take advantage of the fact that quantum projection noise approaches zero as the measured state approaches a basis state. Using this protocol, we are able to measure a frequency separation of 200Hz with a sensitivity of $11~Hz/\sqrt{\rm{Hz}}$ at a measurement time of only 2ms.
*S.M. acknowledges support by an appointment to the Intelligence Community Postdoctoral Research Fellowship Program at UC Berkeley, administered by Oak Ridge Institute for Science and Education through an interagency agreement between the U.S. Department of Energy and the Office of the Director of National Intelligence.
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