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arXiv:1412.2585 · Physical Review A

Mutual information as an order parameter for quantum synchronization

Vahid Ameri, Mohammad Eghbali‐Arani, Andrea Mari, Alessandro Farace, Fardin Kheirandish, Vittorio Giovannetti, Rosario Fazio

Published Jan 5, 2015• 148 citations
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Abstract

Spontaneous synchronization is a fundamental phenomenon, important in many theoretical studies and applications. Recently, this effect has been analyzed and observed in a number of physical systems close to the quantum-mechanical regime. In this work we propose mutual information as a useful order parameter which can capture the emergence of synchronization in very different contexts, ranging from semiclassical to intrinsically quantum-mechanical systems. Specifically, we first study the synchronization of two coupled Van der Pol oscillators in both classical and quantum regimes and later we consider the synchronization of two qubits inside two coupled optical cavities. In all these contexts, we find that mutual information can be used as an appropriate figure of merit for determining the synchronization phases independently of the specific details of the system.

DOI
10.1103/physreva.91.012301

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Spontaneous synchronization is a fundamental phenomenon, important in many theoretical studies and applications. Recently, this effect has been analyzed and observed in a number of physical systems close to the quantum-mechanical regime. In this work we propose mutual information as a useful order parameter which can capture the emergence of synchronization in very different contexts, ranging from semiclassical to intrinsically quantum-mechanical systems. Specifically, we first study the synchronization of two coupled Van der Pol oscillators in both classical and quantum regimes and later we consider the synchronization of two qubits inside two coupled optical cavities. In all these contexts, we find that mutual information can be used as an appropriate figure of merit for determining the synchronization phases independently of the specific details of the system.
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The emergence of mutual synchronization between oscillators, largely studied in classical systems, is explored in quantum systems. After reviewing recent research about the quantum aspects of this phenomenon, we present results obtained in the case of coupled harmonic oscillators with different natural frequencies. The presence of different dissipation processes, described by common or separate heat baths, plays a crucial role in the dynamical properties of the system. We show that mutual synchronization phenomena may appear only for a common bath. Furthermore we show that the emergence of synchronization is related to robust quantum correlations between the oscillators. Synchronization phenomena appear indeed in correspondence with large plateau where mutual information and quantum discord decay slowly, showing for the first time a quantum feature of spontaneous synchronization.