Continuous Variable Entanglement in an Optical Parametric Oscillator Based on a Nondegenerate Four Wave Mixing Process in Hot Alkali Atoms

Abstract

We present the measurement of entanglement between twin beams generated with a doubly resonant optical parameter oscillator (OPO) based on four-wave mixing in hot 85 Rb vapor above threshold. This is the first measurement of entanglement in an OPO with χ (3) media above threshold. We reconstruct the covariance matrix for several configurations and with a full picture of the four side band mode state, we study entanglement between all possible bi-partitions. We show a robust generation of entanglement with stronger generation for a specific pair of modes. For this system, we show that atomic density is a determinant factor for generation and loss of quantum correlations. The generation of entangled fields by an atomic OPO close to atomic resonance of alkali atoms enables natural integration into quantum networks.

Covariance matrix reconstruction of nonclassical light generated in an on-chip optical parametric oscillator

“…The characterization of microcavity chosen from now quality factors, losses and expected squeezing are summarized in table 3.1. It is worth to note that the finesse of the optical cavity is of same order of magnitude of typical mirror-based OPOs [14,19,130].…”

“…In that sense nonclassical light may exercise a central role in future technologies as quantum information carriers that interconnect different on-chip quantum systems in future integrated quantum networks [2]. A recent review exploring the different aspects of several materials that are used in quantum photonics can be found in [13] The Laboratory of Coherent Manipulation of Atoms and Light (LMCAL) is specialized in the generation of bright nonclassical light by means of optical parametric oscillation [14][15][16][17][18][19], achieved by continuously pumping non-linear media in an optical resonator [20,21] above a certain optical power threshold. Low-threshold oscillation is attained by taking advantage of silicon-based materials third-order nonlinearity, dispersion group velocity [22] and the high confinement of light in integrated optical microcavities [23,24].…”