Abstract
We introduce the concept of degree of quantumness in quantum synchronization, a measure of the quantum nature of synchronization in quantum systems. Following techniques from quantum information, we propose the number of non-commuting observables that synchronize as a measure of quantumness. This figure of merit is compatible with already existing synchronization measurements, and it captures different physical properties. We illustrate it in a quantum system consisting of two weakly interacting cavity-qubit systems, which are coupled via the exchange of bosonic excitations between the cavities. Moreover, we study the synchronization of the expectation values of the Pauli operators and we propose a feasible superconducting circuit setup. Finally, we discuss the degree of quantumness in the synchronization between two quantum van der Pol oscillators.
Highlights
Synchronization is originally defined as a process in which two or more self-sustained oscillators evolve to swing in unison
In this Article, we address the problem of how quantum a quantum synchronization process is from the point of view of quantum information
We briefly discuss the extension of the concept of degree of quantumness to infinite-dimensional quantum systems, as is the case of quantum van der Pol oscillators
Summary
The lack of a classical counterpart makes the definition of synchronization non-trivial, and it has been addressed by studying periodically oscillating observables, and recently has been addressed considering local dissipation[25,26] These approach have been further validated by measures of quantum correlations, such as quantum mutual information[27], and the first practical applications in qubits have been recently presented[28,29,30]. The mutual information was proposed as an order parameter for signaling the presence or absence of quantum synchronization[27] This quantifier is not sufficient to answer the question of how quantum this process is and, one could straightforwardly engineer quantum dynamics in which only one observable is synchronized. We extend this idea to quantum synchronization, constructing a quantifier of the quantumness of the process
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
