Continuous-variable quantum key distribution in non-Markovian channels

Vasile, Ruggero; Olivares, Stefano; Paris, Matteo G. A.; Maniscalco, Sabrina

doi:10.1103/physreva.83.042321

Cited by 150 publications

(135 citation statements)

References 33 publications

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“…[10]) to the system, a fact which has interesting ramifications from the perspective of quantum information theory [11]. For example, non-Markovian processes have been shown to preserve entanglement [12] in many-body [13] and biomolecular [14] systems, and have been exploited in quantum key distribution [15], enhancing precision in quantum metrology [16], and implementing certain quantum information protocols [17,18]. Non-Markovianity also plays a detrimental role in quantum Darwinism, thus impeding the emergence of classical objectivity from a quantum world [19].…”

Section: Introductionmentioning

confidence: 99%

Characterizing non-Markovianity via quantum interferometric power

2015

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Non-Markovian evolution in open quantum systems is often characterized in terms of the backflow of information from environment to system and is thus an important facet in investigating the performance and robustness of quantum information protocols. In this work, we explore non-Markovianity through the breakdown of monotonicity of a metrological figure of merit, called the quantum interferometric power, which is based on the minimal quantum Fisher information obtained by local unitary evolution of one part of the system, and can be interpreted as a quantifier of quantum correlations beyond entanglement. We investigate our proposed non-Markovianity indicator in two relevant examples. First, we consider the action of a single-party dephasing channel on a maximally entangled two-qubit state, by applying the Jamiołkowski-Choi isomorphism. We observe that the proposed measure is consistent with established non-Markovianity quantifiers defined using other approaches based on dynamical divisibility, distinguishability, and breakdown of monotonicity for the quantum mutual information. Further, we consider the dynamics of two-qubit Werner states, under the action of a local, single-party amplitude damping channel, and observe that the nonmonotonic evolution of the quantum interferometric power is more robust than the corresponding one for entanglement in capturing the backflow of quantum information associated with the non-Markovian process. Implications for the role of non-Markovianity in quantum metrology and possible extensions to continuous variable systems are discussed.

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Section: Introductionmentioning

confidence: 99%

Characterizing non-Markovianity via quantum interferometric power

2015

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“…We start the analysis evaluating the non-Markovianity of the channel for coherent states and squeezed states. These results are shown in Fig.1, where we plot for both classes the non-Markovianity evaluated at first order, together with the exact numerical solution obtained by maximizing (14) using the full solution (10). The coherent states maximization has been carried out over all the parameters involved and their domain, while for squeezed states we consider two fixed values of the angle φ between the squeezing directions and then maximize over the magnitudes r 1 and r 2 , with the maximum value reached for r 1 = r 2 .…”

Section: Damping Master Equationmentioning

confidence: 99%

“…(4) we obtain the expression for the fidelity in the weak coupling limit. The divisibility property of (9) here is equivalent to the condition γ(t) ≥ 0 for any t ≥ 0, as it can be easily verified from the solution (10). On the other hand, the condition for non-Markovianity can be studied by inspecting the derivative of the fidelity with respect to time.…”

Section: Damping Master Equationmentioning

confidence: 99%

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Quantifying non-Markovianity of continuous-variable Gaussian dynamical maps

et al. 2011

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We introduce a non-Markovianity measure for continuous variable open quantum systems based on the idea put forward in H.-P. Breuer et al. Phys. Rev. Lett.103, 210401 (2009), i.e., by quantifying the flow of information from the environment back to the open system. Instead of the trace distance we use here the fidelity to assess distinguishability of quantum states. We employ our measure to evaluate non-Markovianity of two paradigmatic Gaussian channels: the purely damping channel and the quantum Brownian motion channel with Ohmic environment. We consider different classes of Gaussian states and look for pairs of states maximizing the backflow of information. For coherent states we find simple analytical solutions, whereas for squeezed states we provide both exact numerical and approximate analytical solutions in the weak coupling limit.

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“…For this reason a great deal of attention has been devoted to the study of the corresponding non-Markovian dynamics in different systems ranging from quantum optics to mechanical oscillators and harmonic lattices [46][47][48][49][50][51][52][53][54]. In addition, there is evidence that non-Markovian open quantum systems [55][56][57][58][59] can be useful for quantum technology [60][61][62].…”

Section: Introductionmentioning

confidence: 99%

Collapse and revival of quantum coherence for a harmonic oscillator interacting with a classical fluctuating environment

et al. 2015

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We address the dynamics of nonclassicality for a quantum system interacting with a noisy fluctuating environment described by a classical stochastic field. As a paradigmatic example, we consider a harmonic oscillator initially prepared in a maximally nonclassical state, e.g., a Fock number state or a Schrödinger-cat-like state, and then coupled to either a resonant or a nonresonant external field. Stochastic modeling allows us to describe the decoherence dynamics without resorting to approximated quantum master equations and to introduce non-Markovian effects in a controlled way. A detailed comparison among different nonclassicality criteria and a thorough analysis of the decoherence time reveal a rich phenomenology whose main features may be summarized as follows: (i) Classical memory effects increase the survival time of quantum coherence and (ii) a detuning between the natural frequency of the system and the central frequency of the classical field induces revivals of quantum coherence.

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Continuous-variable quantum key distribution in non-Markovian channels

Cited by 150 publications

References 33 publications

Characterizing non-Markovianity via quantum interferometric power

Characterizing non-Markovianity via quantum interferometric power

Quantifying non-Markovianity of continuous-variable Gaussian dynamical maps

Collapse and revival of quantum coherence for a harmonic oscillator interacting with a classical fluctuating environment

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