Gaussian-State Theory of Two-Photon Imaging

TL;DR

This paper extends Gaussian-state analysis to two biphoton imaging scenarios, demonstrating that classical states with phase-sensitive cross correlations can replicate quantum resolution performance in far-field diffraction and broadband lens imaging.

Contribution

It introduces a Gaussian-state framework for additional biphoton imaging setups, showing classical states can match quantum resolution through phase-sensitive correlations.

Findings

Resolution depends on phase-sensitive cross correlation.

Classical states can replicate quantum imaging resolution.

Gaussian-state analysis applies to new imaging configurations.

Abstract

Biphoton states of signal and idler fields--obtained from spontaneous parametric downconversion (SPDC) in the low-brightness, low-flux regime--have been utilized in several quantum imaging configurations to exceed the resolution performance of conventional imagers that employ coherent-state or thermal light. Recent work--using the full Gaussian-state description of SPDC--has shown that the same resolution performance seen in quantum optical coherence tomography and the same imaging characteristics found in quantum ghost imaging can be realized by classical-state imagers that make use of phase-sensitive cross correlations. This paper extends the Gaussian-state analysis to two additional biphoton-state quantum imaging scenarios: far field diffraction-pattern imaging; and broadband thin-lens imaging. It is shown that the spatial resolution behavior in both cases is controlled by the nonzero phase-sensitive cross correlation between the signal and idler fields. Thus, the same resolution can be achieved in these two configurations with classical-state signal and idler fields possessing a nonzero phase-sensitive cross correlation.