Multiphoton catalysis with coherent state input: nonclassicality and decoherence

Abstract

We propose a scheme to generate a new kind of non-Gaussian state—the Laguerre polynomial excited coherent state (LPECS)—by using multiphoton catalysis with coherent state input. The nonclassical properties of the LPECS are studied in terms of nonclassical depth, Mandel’s parameter, second-order correlation, quadrature squeezing, and the negativity of the Wigner function (WF). It is found that the LPECS is highly nonclassical and its nonclassicality depends on the amplitude of the coherent state, the catalysis photon number, and the parameters of the unbalanced beam splitter (BS). In particular, the maximum degree of squeezing can be enhanced by increasing the catalysis photon number. In addition, we examine the effect of decoherence using the WF, which shows that the negative region, the characteristic time of decoherence, and the structure of the WF are affected by catalysis photon number and the parameters of the unbalanced BS. Our work provides general analysis on how to prepare polynomial quantum states, which may be useful in the fields of quantum information and quantum computation.

Continuous-variable quantum key distribution with non-Gaussian 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.…”

Continuous‐Variable Entanglement and Wigner‐Function Negativity via Adding or Subtracting Photons

“…Notably, different from the photon addition and subtraction, multiphoton quantum catalysis as a superposition of number‐conserving operation [ 7 ] can enhance or weaken the entanglement of the system without adding/subtracting photons to/from the system. Current researches show that, using this operation and carrying out conditional measurements on beam splitters, coherent superposition states and Laguerre polynomial excited coherent states are theoretically produced, [ 89–91 ] and a series of multiphoton nonclassical states are experimentally prepared. [ 92 ] More recent, Hu et al.…”

Nonclassicality and decoherence of photon-added squeezed coherent Schrödinger kitten states in a Kerr medium

“…The greatest lower bound of the smoothing parameter σ that renders the R-distribution of a relevant quantum state positive semidefinite may be regarded [35] as its measure of nonclassicality. Using this procedure the nonclassical depths of various states have been investigated [35][36][37][38]. Towards evaluating the distribution R(β, β * ; σ) for the quantum state studied here we substitute the P -representation (2.15) in the definition (2.59).…”

“…The nonclassical depth has recently been used [37] to assess the nonclassicality of superposition of quantum states prepared by permutations of nondemolition quadrature experiments and single quanta addition or subtraction. It has also been applied [38] in quantitatively determining the nonclassicality of the non-Gaussian states prepared by utilizing the multiphoton catalysis with coherent state input. We obtain analytical expressions of the R(t)-distribution for the short-lived kitten-like structures, and numerically find that these states are associated with the maximum possible nonclassical depth.…”