Phase Diffusion in Quantum Dissipative Systems

Abstract

We study the dynamics of the quantum phase distribution associated with the reduced density matrix of a system for a number of situations of practical importance, as the system evolves under the influence of its environment, interacting via a quantum nondemoliton type of coupling, such that there is decoherence without dissipation, as well as when it interacts via a dissipative interaction, resulting in decoherence as well as dissipation. The system is taken to be either a two-level atom (or equivalently, a spin-1/2 system) or a harmonic oscillator, and the environment is modeled as a bath of harmonic oscillators, starting out in a squeezed thermal state. The impact of the different environmental parameters on the dynamics of the quantum phase distribution for the system starting out in various initial states, is explicitly brought out. An interesting feature that emerges from our work is that the relationship between squeezing and temperature effects depends on the type of system-bath interaction. In the case of quantum nondemolition type of interaction, squeezing and temperature work in tandem, producing a diffusive effect on the phase distribution. In contrast, in case of a dissipative interaction, the influence of temperature can be counteracted by squeezing, which manifests as a resistence to randomization of phase. We make use of the phase distributions to bring out a notion of complementarity in atomic systems. We also study the dispersion of the phase using the phase distributions conditioned on particular initial states of the system.

Accepted for publication in Physical Review A; changes in section V; 20 pages, 12 figures

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• Characterization of Unruh Channel in the context of Open Quantum Systems
• Quantum phase properties of photon added and subtracted displaced Fock states
• Impact of photon addition and subtraction on nonclassical and phase properties of a displaced Fock state
• Complementarity in generic open quantum systems
• Complementarity in atomic (finite-level quantum) systems: an information-theoretic approach
• Phase Squeezing of Quantum Hypergraph States
• A robust hybrid receiver for binary phase-shift keying discrimination in the presence of phase noise
• The lower bound to the concurrence for four-qubit W state under noisy channels
• Complementarity in atomic and oscillator systems
• Quantum communications in continuous variable systems
• Husimi phase distribution in non-Gaussian operations
• An investigation on the nonclassical and quantum phase properties of a family of engineered quantum states