Generation of entangled coherent states via cross-phase-modulation in a double electromagnetically induced transparency regime

Abstract

The generation of an entangled coherent state is one of the most important ingredients of quantum information processing using coherent states. Recently, numerous schemes to achieve this task have been proposed. In order to generate travelling-wave entangled coherent states, cross phase modulation, optimized by optical Kerr effect enhancement in a dense medium in an electromagnetically induced transparency (EIT) regime, seems to be very promising. In this scenario, we propose a fully quantized model of a double-EIT scheme recently proposed [D. Petrosyan and G. Kurizki, Phys. Rev. A 65, 33833 (2002)]: the quantization step is performed adopting a fully Hamiltonian approach. This allows us to write effective equations of motion for two interacting quantum fields of light that show how the dynamics of one field depends on the photon-number operator of the other. The preparation of a Schrödinger cat state, which is a superposition of two distinct coherent states, is briefly exposed. This is based on non-linear interaction via double-EIT of two light fields (initially prepared in coherent states) and on a detection step performed using a 50 : 50 beam splitter and two photodetectors. In order to show the entanglement of an entangled coherent state, we suggest to measure the joint quadrature variance of the field. We show that the entangled coherent states satisfy the sufficient condition for entanglement based on quadrature variance measurement. We also show how robust our scheme is against a low detection efficiency of homodyne detectors.

Control of Fano resonances and slow light using Bose-Einstein condensates in a nanocavity

“…These platforms offer the possibility of a generation of highly-sensitive sensors, which are able to detect (for example) weak forces, with a precision limited only by quantum uncertainties [39]. Fano resonances [40,41], optomechanically induced transparency [42] with single [43] and multiple windows [41,44,45], superluminal and subluminal effects [46][47][48][49][50][51][52][53][54][55][56][57][58][59] have also been observed in optomechanical systems, where nano dimensions and normal environmental conditions have paved the new avenues towards stateof-the-art potential applications, such as imaging and cloaking, telecommunication, interferometry, quantumoptomechanical memory and classical signal processing applications [60][61][62][63].…”

A macroscopical entangled coherent state generator in a V configuration atom system

“…Numerous schemes have been proposed to generate such an entangled coherent state [2,3,4,6,7,8,9,10]. A scheme based on a double electromagnetically induced transparency system has been proposed in reference [2].…”

“…Numerous schemes have been proposed to generate such an entangled coherent state [2,3,4,6,7,8,9,10]. A scheme based on a double electromagnetically induced transparency system has been proposed in reference [2]. As for ion trap systems, the vibrational motion of ions [3] and the entanglement swapping [4] seems promising to generate an entangled coherent state.Using Kerr nonlinearity and a 50/50 beam splitter,multidimensional entangled coherent states can be generated on the condition that the initial state is a coherent state and the interaction times are within certain range [5].…”

Deterministic generation of tailored-optical-coherent-state superpositions

“…In principle they allow quantum teleportation and linear quantum gates in a straightforward manner [4]. Although nondeterministic sources could be used for these applications it would clearly be more desirable if a controlled deterministic source was available in the optical domain.Nonlinear optical setups, such as, e.g., a subthreshold optical parametric oscillator or electrically induced transparency type interactions in atomic media, have been suggested as possible sources of such states [5]. Alternatively, traveling-wave coherent-superposition states might be generated by sending a three-level atom in a superposition state of the two lower levels through a high-Q cavity, which couples only one of the levels with a third upper state [6].…”

“…Nonlinear optical setups, such as, e.g., a subthreshold optical parametric oscillator or electrically induced transparency type interactions in atomic media, have been suggested as possible sources of such states [5]. Alternatively, traveling-wave coherent-superposition states might be generated by sending a three-level atom in a superposition state of the two lower levels through a high-Q cavity, which couples only one of the levels with a third upper state [6].…”