Generation of degenerate, factorizable, pulsed squeezed light at telecom   wavelengths
  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. 
Thomas Gerrits, Martin J. Stevens, Burm Baek, Brice Calkins, Adriana   Lita, Scott Glancy, Emanuel Knill, Sae Woo Nam, Richa...
quant-ph physics.optics