arXiv subjects

Priyanka Chowdhury

Publications and source records attributed to Priyanka Chowdhury.

4 recordsLinked to original sources

arXiv2026

Incompatibility of optimized protection of entanglement and teleportation fdelity in the presence of decoherence

Entanglement is the key success of teleporting an unknown quantum state with fidelity higher than classical limit. In the presence of decoherence, entanglement decreases with the strength of interaction between quantum systems and the environment. As a result, teleportation fidelity (TF) decreases. The technique of weak measurement and its reversal help to protect entanglement in the presence of amplitude-damping decoherence. In this work, we have shown that the optimal protection of entanglement does not optimize TF. More specifically, when one of the systems interacts with the environment, optimized TF requires higher strength of reverse weak measurement than optimized entanglement protection. The success probability of optimal protection indicates that higher form of nonlocal correlation plays the key role in optimizing TF. Interestingly, when both systems interact with the environment, optimization of entanglement implies optimization of TF. Therefore, the resources of quantum teleportation along with entanglement need to be explored.

quant-ph↗

arXiv2015

Stronger steerability criterion for more uncertain continuous variable systems

We derive a fine-grained uncertainty relation for the measurement of two incompatible observables on a single quantum system of continuous variables, and show that continuous variable systems are more uncertain than discrete variable systems. Using the derived fine-grained uncertainty relation, we formulate stronger steering criterion that is able to reveal the steerability of N00N states that has hitherto not been possible using other criteria. We further obtain a monogamy relation for our steering inequality which leads to an, in principle, improved lower bound on the secret key rate of a one-sided device independent quantum key distribution protocol for continuous variables.

quant-ph↗

arXiv2014

Einstein-Podolsky-Rosen-steering using quantum correlations in non-Gaussian entangled states

In view of the increasing importance of non-Gaussian entangled states in quantum information protocols like teleportation and violations of Bell inequalities, the steering of continuous variable non-Gaussian entangled states is investigated. The EPR steering for Gaussian states may be demonstrated through the violation of the Reid inequality involving products of the inferred variances of non-commuting observables. However, for arbitrary states the Reid inequality is not always necessary because of the higher order correlations in such states. One then needs to use the entropic steering inequality. We examine several classes of currently important non-Gaussian entangled states, such as the two-dimensional harmonic oscillator, the photon subtracted two mode squeezed vacuum, and the NOON state, in order to demonstrate the steering property of such states. A comparative study of the violation of the Bell-inequality for these states shows that the entanglement present is more easily revealed through steering compared to Bell-violation for several such states.

quant-ph↗

arXiv2013

Nonlocal continuous variable correlations and violation of Bell's inequality for light beams with topological singularities

We consider optical beams with topological singularities which possess Schmidt decomposition and show that such classical beams share many features of two mode entanglement in quantum optics. We demonstrate the coherence properties of such beams through the violations of Bell inequality for continuous variables using the Wigner function. This violation is a consequence of correlations between the $(x, p_x)$ and $(y, p_y)$ spaces which mathematically play the same role as nonlocality in quantum mechanics. The Bell violation for the LG beams is shown to increase with higher orbital angular momenta $l$ of the vortex beam. This increase is reminiscent of enhancement of nonlocality for many particle Greenberger-Horne-Zeilinger states or for higher spins. The states with large $l$ can be easily produced using spatial light modulators.

quant-ph↗