arXiv subjects

Momir Arsenijevic

Publications and source records attributed to Momir Arsenijevic.

5 recordsLinked to original sources

arXiv2017

Kraus operators for a pair of interacting qubits: a case study

The Kraus form of the completely positive dynamical maps is appealing from the mathematical and the point of the diverse applications of the open quantum systems theory. Unfortunately, the Kraus operators are poorly known for the two-qubit processes. In this paper, we derive the Kraus operators for a pair of interacting qubit, while the strength of the interaction is arbitrary. One of the qubits is subjected to the x-projection spin measurement. The obtained results are applied to calculate the dynamics of the initial entanglement in the qubits system. We obtain the loss of the correlations in the finite time interval; the stronger the inter-qubit interaction, the longer lasting entanglement in the system.

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arXiv2017

Generalized Kraus operators for the one-qubit depolarizing quantum channel

Microscopic Hamiltonian models of the composite system "open system + environment" typically do not provide the operator-sum Kraus form of the open system's dynamical map. With the use of a recently de- veloped method [16], we derive the Kraus operators starting from the mi- croscopic Hamiltonian model, i.e. from the proper master equation, of the one-qubit depolarizing channel. Those Kraus operators generalize the stan- dard counterparts, which are widely used in the literature. Comparison of the standard and the here obtained Kraus operators is performed via inves- tigating dynamical change of the Bloch sphere volume, entropy production and the open system's state trace distance. We find that the standard depo- larizing channel is more deteriorating than the generalized one.

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arXiv2016

Collective versus individual classicality for a pair of interacting qubits immersed in independent local environments

There is current interest in investigating which variables play an important role in the physical processes with an open composite quan- tum system that ranges from the foundational issues to the tasks of diverse applications in quantum physics and technology. In this paper we contrast the local versus the collective classical-like behavior of a pair of interacting qubits immersed in the mutually independent thermal baths. The qubits can be locally subjected to any of the standard, microscopically modelled, generalized amplitude damping and phase damping channel, as well as to the recently introduced generalized depolarizing channel. As a criterion for the classical-like behavior we use the least entropy production, i.e. the total correlation in the system. The classical-like collective behavior is found for short time intervals for strongly interacting qubits. Only in a certain trivial case we observe the simultaneous collective and individual-qubits classical- ity. Observation (non-observation) of the collective (individual) classicality can reveal the kind and strength of the qubits interaction or the ratio of the qubits' energy-gaps, while manipulating the qubits interaction (by tuning the strength and/or refocussing) can give rise to the desired kind of classicality.

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arXiv2016

Microscopic derivation of the one qubit Kraus operators for amplitude and phase damping

This article presents microscopic derivation of the Kraus operators for (the generalized) amplitude and phase damping process. Derivation is based on the recently developed method [Andersson et al, J. Mod.Opt. 54, 1695 (2007)] which concerns finite dimensional systems (e.g. qubit). The form of these operators is usually estimated without insight into the microscopic details of the dynamics. The behavior of the qubit dynamics is simulated and depicted via Bloch sphere change.

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arXiv2014

Quantum Structures: A View of the Quantum World

We offer a systematic account of decomposition of quantum systems into parts. Different decompositions (structures) are mutually linked via the proper linear canonical transformations. Different kinds of structures, as well as their relations, are considered. Emphasis is placed on mutually global and irreducible structures. Is there a privileged structure of the closed system? Is there a preferred (bipartite) structure of an open system? Are there any practical advantages of certain alternative structures of the system? Is there a simple dynamical relation for a pair of structures? The [necessarily partial] answers are rather intriguing. Relativity of quantum correlations (that include entanglement as well as the "one-way" and "two-way" discord) is carefully presented. Emphasis is placed on the "parallel occurrence of decoherence" in the quantum Brownian motion. The environment-selected preferred structure of an open composite system is presented for a pair of harmonic oscillators (or the field modes). A limitation of the Nakajima-Zwanzig projection method appears as a consequence of quantum correlations relativity. Hence, describing dynamics of an alternate open-system is a delicate task. Certain interpretational issues, which include "quantum reference frames" issue, are discussed. Some recent experiments are also discussed. To this end, the option that "there are no particles" on the most fundamental physical level naturally follows. Certain open questions and prospects for further research are highlighted.

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