We construct a distinct class of nonlinear displaced Kerr states by application of the displacement operator upon a state which is prepared by sending the well-known photon-added coherent state through a normal Kerr medium. A sketch for the experimental setup for preparing the state is suggested. We evaluate some statistical properties such as the photon number distribution, Mandel's Q parameter, Husimi-Q and Wigner functions, and quadrature squeezing for the nonlinear displaced Kerr state and then analyze the nonclassicality in terms of these standard parameters. We reduce the infinite-level problem to a truncated discrete two-level system by using a low Kerr parameter approximation and then convert the generated nonclassicality into bipartite entanglement between the two modes of an output state of a linear optical device. © 2016 Optical Society of America.

Rupamanjari Ghosh

SNU Management

Chatterjee A.

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Nonlinear displaced Kerr state and its nonclassical properties

Journal of the Optical Society of America B: Optical Physics

We investigate the states generated in continuous variable (CV) optical fields by operating them with a number-conserving operator of the type sa + ta, formed by the generalized superposition of products of field annihilation (a) and creation (a) operators, with s2 + t2 = 1. Such an operator is experimentally realizable and can be suitably manipulated to generate nonclassical optical states when applied on single- and two-mode coherent, thermal and squeezed input states. At low intensities, these nonclassical states can interact with a secondary mode via a linear optical device to generate two-mode discrete entangled states, which can serve as a resource in quantum information protocols. The advantage of these operations are tested by applying the generated entangled states as quantum channels in CV quantum teleportation, under the Braunstein and Kimble protocol. We observe that, under these operations, while the average fidelity of CV teleportation is enhanced for the nonclassical channel formed using input squeezed states, it remains at the classical threshold for input coherent and thermal states. This is due to the fact that though these operations can introduce discrete entanglement in all input states, it enhances the EinsteinPodoloskyRosen correlations only in the nonclassical squeezed state inputs, leading to an advantage in CV teleportation. This shows that nonclassical optical states generated using the above operations on classical coherent and thermal state inputs are not useful for CV teleportation. This investigation could prove useful for the efficient implementation of noisy non-Gaussian channels, formed by linear operations, in future teleportation protocols. © 2015 IOP Publishing Ltd Printed in the UK.

Fulltext

Journal of Physics B: Atomic, Molecular and Optical Physics

Generating continuous variable entangled states for quantum teleportation using a superposition of number-conserving operations

We consider an experimentally realizable scheme for manipulating quantum states using a general superposition of products of field annihilation (â) and creation (â †) operators of the type (sââ † + tâ †â), with s 2 + t 2 = 1. Such an operation, when applied on states with classical features, is shown to introduce strong nonclassicality. We quantify the generated degree of nonclassicality by the negative volume of Wigner distribution in the phase space and investigate two other observable nonclassical features, sub-Poissonian statistics and squeezing. We find that the operation introduces negativity in the Wigner distribution of an input coherent state and changes the Gaussianity of an input thermal state. This provides the possibility of engineering quantum states with specific nonclassical features. © 2012 IOP Publishing Ltd.