Generation of degenerate, factorizable, pulsed squeezed light at telecom wavelengths

TL;DR

This paper reports on the generation and characterization of degenerate, factorizable, pulsed squeezed light at telecom wavelengths using a periodically poled KTP crystal, demonstrating high-visibility Hong-Ou-Mandel interference and photon number correlations.

Contribution

The work introduces a method to produce nearly factorizable, pulsed squeezed states with minimal unwanted modes at telecom wavelengths, verified through advanced photon detection techniques.

Findings

High-visibility Hong-Ou-Mandel interference (86-95%)

Successful generation of factorizable, pulsed squeezed states

Consistent photon number distribution measurements with different detectors

Abstract

We characterize a periodically poled KTP crystal that produces an entangled, two-mode, squeezed state with orthogonal polarizations, nearly identical, factorizable frequency modes, and few photons in unwanted frequency modes. We focus the pump beam to create a nearly circular joint spectral probability distribution between the two modes. After disentangling the two modes, we observe Hong-Ou-Mandel interference with a raw (background corrected) visibility of 86 % (95 %) when an 8.6 nm bandwidth spectral filter is applied. We measure second order photon correlations of the entangled and disentangled squeezed states with both superconducting nanowire single-photon detectors and photon-number-resolving transition-edge sensors. Both methods agree and verify that the detected modes contain the desired photon number distributions.