Entanglement improvement of entangled coherent state via multiphoton catalysis

Abstract

Based on the conditional measurement and beam splitters, multi-photon catalysis is introduced to each mode of even entangled coherent states (EECSs). The resulted states belong to a kind of Laguerre polynomials excited EECSs. Then the entanglement properties of resulted state are examined according to EPR correlation, concurrence and the teleportation fidelity. For the symmetrical beam splitters, these three quantities can be improved by multi-photon catalysis (⩾3) and only EPR correlation can be enhanced by zero-photon catalysis. Our optimal results over transmissivities of beam splitters show that the unit concurrence can be achieved for all non-zero photon catalysis which indicates that the optimized output approaches Belltype state. In addition, two single-photon catalysis and zero-photon catalysis present better performance for the improvement of both the EPR correlation and the teleportation fidelity in small and large amplitude regions, respectively. Particularly, it is interesting to notice that both of them can be optimized to be constant for zero-photon catalysis when the amplitude exceeds a certain threshold.

Continuous-variable quantum key distribution with non-Gaussian quantum catalysis

“…where L n (·) denotes the Laguerre polynomials (see Refs. [42,43] for the detailed calculation). By using the generating function of Laguerre polynomials, i.e.,…”

“…The reason may be that for the single-photon BSQC, extra adding the model of quantum catalysisÔ m before Alice taking heterodyne detection can be regarded as the generation of trusted noise controlled by Alice, thereby resulting in the diminution of the Holevo bound S G (B:E). However, for the two-photon QC-CVQKD system, the BSQC [cyan dashdotted line] and SSQC [orange dotted line] are worse than the original one, resulted from the fact that the more photons are catalyzed, the higher the non-Gaussianity is, thereby making the more noise to the covariance matrix [42,43]. In addition, Within the shortening distance, the secret key of the QC-CVQKD system is worse than that of the original system because of the limitation of the success probability of quantum catalysis.…”

“…In order to overcome the limitation, in this paper, we propose an improved modulation scheme for CVQKD by using another non-Gaussian operation, the quantum catalysis (QC) [41], which can be implemented with current experimental technologies. Attractively, the quantum catalysis operation is a feasible way to enhance the nonclassicality [42] and the entanglement property of Gaussian entangled states [43], thereby has become one of the research hotspots in quantum physics. Different from the previous studied photon-subtraction operations, although no photon is subtracted and added in quantum catalysis process, quantum catalysis can be applied to facilitate the conversion of the target ensemble, which could prevent the loss of information effectively.…”

Off-Resonance Control and All-Optical Switching: Expanded Dimensions in Nonlinear Optics

“…The terms is also used in a different connection relating to beam splitting. Here, optical catalysts have been extensively studied [10][11][12][13] and suggested as a method for improved performance of continuous-variable quantum key distribution systems [14]. Moreover, in connection to the photolysis of isolated phenol molecules, a strong off-resonant infrared electromagnetic field has recently been shown to lower the activation barrier to photolysis via a dynamic Stark shift [15], signifying a form of optical catalysis whose effect is also analogous those detailed in this review.…”

Multimode CV‐QKD with non‐Gaussian operations

“…CV‐QKD protocols with non‐Gaussian operations, such as photon subtraction and photon catalysis, has garnered great interest over the past few years 1‐9 . This is so partially because such operations are critical steps for quantum information tasks such as quantum error correction 10 and noiseless amplification, 11‐13 and that they have the potential to enhance the level of entanglement of entangled states such as Einstein‐Podolsky‐Rosen (EPR) states 14‐18 . It is natural to hypothesize that non‐Gaussian states can also boost the secret key rate of entanglement‐based CV‐QKD protocols.…”