Entanglement and the Einstein-Podolsky-Rosen paradox with coupled intracavity optical down-converters

Abstract

We show that two evanescently coupled ͑2͒ parametric down-converters inside a Fabry-Perot cavity provide a tunable source of quadrature squeezed light, Einstein-Podolsky-Rosen ͑EPR͒ correlations and quantum entanglement. Analyzing the operation in the below threshold regime, we show how these properties can be controlled by adjusting the coupling strengths and the cavity detunings. As this can be implemented with integrated optics, it provides a possible route to rugged and stable EPR sources.

Bright bichromatic entanglement and quantum dynamics of sum frequency generation

“…In the figure, we have used the labels EPRij to represent the product V inf (X i )V inf (Ŷ i ) and have chosen a regime where the linearisation process is valid. We also note here that previous coupled systems which have been predicted to produce entangled outputs via evanescently coupled intracavity χ (2) and χ (3) processes could also be arranged asymmetrically and thus may also be good candidates for the production of asymmetric steering [35,45,46,47,48].…”

Entanglement Generated in a Semiconductor Microcavity

“…In our system the elements of covariance matrix can be obtained as Figure 2 plots the logarithmic negativity characterized CV entanglement between the cavity and exciton with different values of the coefficient χ , where the loss rate at the fundamental frequency is twice that of the coupling coefficient g. It shows that the maximum values E N move away from zero frequency, and the spectra becomes bifurcated with the coefficient χ increasing. This is different than the cases interacted with ξ (2) coupling [42], where setting the detunings being equal in strength to the evanescent coupling meant the optimal correlations were found at zero quadrature angle. The different behaviors can be account for nonlinear coefficient χ interaction with itself altering the quadrature angles at which the preferable correlations can be measured [43].…”

Object reconstruction from multiplexed quantum ghost images using reduction technique

“…There are various ways of producing multi-frequency entangled light beams. The required states can be obtained, e. g., in consecutive coupled parametric interactions in nonlinear crystals located either outside [11,12] or inside [13] an optical resonator, in nonlinear waveguide structures [14,15] where modes are coupled through evanescent modes, in a spatially modulated pump beam [16]. The considered GI multiplexing employs four-frequency entangled quantum states formed through parametric decay of pump photons into two photons with different frequencies that are mixed in the same crystal with pump photons, which produces photons with sum frequencies [17,18].…”

“…Obviously, in the setup under consideration they will be the same as in [9,10]. After integration over the area of the beam in the object arm (over r 1 ) intensity correlation functions of the second order, in accordance with (13), (14), becomes…”