6 research outputs found
Quantum-limited time-frequency estimation through mode-selective photon measurement
By projecting onto complex optical mode profiles, it is possible to estimate
arbitrarily small separations between objects with quantum-limited precision,
free of uncertainty arising from overlapping intensity profiles. Here we extend
these techniques to the time-frequency domain using mode-selective
sum-frequency generation with shaped ultrafast pulses. We experimentally
resolve temporal and spectral separations between incoherent mixtures of
single-photon level signals ten times smaller than their optical bandwidths
with a ten-fold improvement in precision over the intensity-only Cram\'er-Rao
bound.Comment: Six pages, three figures. Comments welcome
Advances in photonic quantum sensing
Quantum sensing has become a mature and broad field. It is generally related
with the idea of using quantum resources to boost the performance of a number
of practical tasks, including the radar-like detection of faint objects, the
readout of information from optical memories or fragile physical systems, and
the optical resolution of extremely close point-like sources. Here we first
focus on the basic tools behind quantum sensing, discussing the most recent and
general formulations for the problems of quantum parameter estimation and
hypothesis testing. With this basic background in our hands, we then review
emerging applications of quantum sensing in the photonic regime both from a
theoretical and experimental point of view. Besides the state-of-the-art, we
also discuss open problems and potential next steps.Comment: Review in press on Nature Photonics. This is a preliminary version to
be updated after publication. Both manuscript and reference list will be
expande
Reading out Fisher information from the zeros of the point spread function
We show that, for optical systems whose point spread functions exhibit isolated zeros, the information one can gain about the separation between two incoherent point light sources does not scale quadratically with the separation (which is the distinctive dependence causing Rayleigh’s curse) but only linearly. Moreover, the dominant contribution to the separation information comes from regions in the vicinity of these zeros. We experimentally confirm this idea, demonstrating significant superresolution using natural or artificially created spectral doublets