We have examined both single and entangled two-mode multiphoton coherent states and shown how the ‘Janus-faced’ properties between two partner states are mirrored in appropriate tomograms. Entropic squeezing, quadrature squeezing and higher-order squeezing properties for a wide range of nonclassical states are estimated directly from tomograms. We have demonstrated how squeezing properties of two-mode entangled states produced at the output port of a quantum beamsplitter are sensitive to the relative phase between the reflected and transmitted fields. This feature allows for the possibility of tuning the relative phase to enhance squeezing properties of the state. Finally, we have examined the manner in which decoherence affects squeezing and the changes in the optical tomogram of the state due to interaction with the environment. © 2018 Informa UK Limited, trading as Taylor &amp; Francis Group.

S. Lakshmi Bala

Department Of Physics

Pradip Laha

V. Balakrishnan

Optical beam splitters

Optical tomography

Quantum optics

COHERENT STATE

Decoherence

HIGHER-ORDER SQUEEZING

MODE ENTANGLED STATE

NONCLASSICAL PROPERTIES

QUADRATURE SQUEEZING

QUANTUM BEAMSPLITTER

UNCERTAINTY RELATION

Quantum entanglement

Fulltext

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Journal of Modern Optics

We investigate the advantages of extracting the degree of entanglement in bipartite systems directly from tomograms, as it is the latter that are readily obtained from experiments. This would provide a superior alternative to the standard procedure of assessing the extent of entanglement between subsystems after employing the machinery of state reconstruction from the tomogram. The latter is both cumbersome and involves statistical methods, while a direct inference about entanglement from the tomogram circumvents these limitations. In an earlier paper, we had identified a procedure to obtain a bipartite entanglement indicator directly from tomograms. To assess the efficacy of this indicator, we now carry out a detailed investigation using two nonlinear bipartite models by comparing this tomographic indicator with standard markers of entanglement such as the subsystem linear entropy and the subsystem von Neumann entropy and also with a commonly used indicator obtained from inverse participation ratios. The two-model systems selected for this purpose are a multilevel atom interacting with a radiation field, and a double-well Bose–Einstein condensate. The role played by the specific initial states of these two systems in the performance of the tomographic indicator is also examined. Further, the efficiency of the tomographic entanglement indicator during the dynamical evolution of the system is assessed from a time-series analysis of the difference between this indicator and the subsystem von Neumann entropy. © 2019, Springer Science+Business Media, LLC, part of Springer Nature.

Quantum Information Processing

Estimation of entanglement in bipartite systems directly from tomograms

Several nonclassical effects displayed by wave packets governed by nonlinear Hamiltonians can be identified and assessed directly from tomograms without attempting to reconstruct the Wigner function or the density matrix explicitly. We have demonstrated this for both single-mode and bipartite systems. We have shown that a wide spectrum of effects such as the revival phenomena, quadrature squeezing, and Hong-Mandel and Hillery type higher-order squeezing in a generic single-mode system and the double-well Bose-Einstein condensate (BEC) can be obtained from appropriate tomograms in a straightforward manner. We have examined the manner in which decoherence affects the nature of the state of a generic single-mode system at specific instants during temporal evolution. We have investigated entropic squeezing of the subsystem state of a bipartite system as it evolves in time, solely from tomograms. The procedures that we have demonstrated can be readily adapted to multimode systems. Further, for the double-well BEC we have identified an indicator of entanglement between subsystems that can be obtained directly from the tomogram. This mirrors the qualitative behavior of the subsystem von Neumann entropy and the subsystem linear entropy. © 2017 IOP Publishing Ltd.

Journal of Physics B: Atomic, Molecular and Optical Physics

Signatures of nonclassical effects in optical tomograms

We present, for the isospectral family of oscillator Hamiltonians, a systematic procedure for constructing raising and lowering operators satisfying any prescribed "distorted" Heisenberg algebra (including the q-generalization). This is done by means of an operator transformation implemented by a shift operator. The latter is obtained by solving an appropriate partial isometry condition in the Hubert space. Formal representations of the nonlocal operators concerned are given in terms of pseudo-differential operators. Using the new annihilation operators, new classes of coherent states are constructed for isospectral oscillator Hamiltonians. The corresponding Fock-Bargmann representations are also considered, with specific reference to the order of the entire function family in each case. ©1998 American Institute of Physics.

Journal of Mathematical Physics

Ladder operators for isospectral oscillators

Journal of the Optical Society of America B

Signatures of entanglement in an optical tomogram

Physical Review A

Visualizing revivals and fractional revivals in a Kerr medium using an optical tomogram

Physical Review Letters

Experimental Generation of Squeezed Cat States with an Operation Allowing Iterative Growth

Estimation of nonclassical properties of multiphoton coherent states from optical tomograms

Journal	Data powered by TypesetJournal of Modern Optics
Publisher	Data powered by TypesetTaylor and Francis Ltd.
ISSN	09500340
Open Access	No