Long-baseline interferometry using single photon states as a non-local oscillator

Matthew Brown, Valerian Thiel, Markus Allgaier, Michael Raymer, Brian Smith, Paul Kwiat, John Monnier

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Recent proposals suggest that distributed single photons serving as a 'non-local oscillator' can outperform coherent states as a phase reference for long-baseline interferometric imaging of weak sources [1,2]. Such nonlocal quantum states distributed between telescopes can, in-principle, surpass the limitations of conventional interferometric-based astronomical imaging approaches for very-long baselines such as: signal-to-noise, shot noise, signal loss, and faintness of the imaged objects. Here we demonstrate in a table-top experiment, interference between a nonlocal oscillator generated by equal-path splitting of an idler photon from a pulsed, separable, parametric down conversion process and a spectrally single-mode, quasi-thermal source. We compare the single-photon nonlocal oscillator to a more conventional local oscillator with uncertain photon number. Both methods enabled reconstruction of the source's Gaussian spatial distribution by measurement of the interference visibility as a function of baseline separation and then applying the van Cittert-Zernike theorem [3,4]. In both cases, good qualitative agreement was found with the reconstructed source width and the known source width as measured using a camera. We also report an increase of signal-to-noise per 'faux' stellar photon detected when heralding the idler photon. 1593 heralded (non-local oscillator) detection events led to a maximum visibility of ∼17% compared to the 10412 unheralded (classical local oscillator) detection events, which gave rise to a maximum visibility of ∼10% - the first instance of quantum-enhanced sensing in this context.

Original languageEnglish (US)
Title of host publicationQuantum Computing, Communication, and Simulation II
EditorsPhilip R. Hemmer, Alan L. Migdall
ISBN (Electronic)9781510649019
StatePublished - 2022
Externally publishedYes
EventQuantum Computing, Communication, and Simulation II 2022 - Virtual, Online
Duration: Feb 20 2022Feb 24 2022

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


ConferenceQuantum Computing, Communication, and Simulation II 2022
CityVirtual, Online


  • Nonlocal Oscillator
  • Quantum Sensing
  • Very-Long-Baseline Interferometry

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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