Quantum resources for hybrid communication via qubit-oscillator states

TL;DR

This paper explores qubit-oscillator states as resources for hybrid quantum communication, analyzing their nonclassical correlations and proposing protocols like teleportation and remote state preparation that can achieve high efficiency even with thermal oscillators.

Contribution

It introduces a family of qubit-oscillator resource states, derives analytical formulas for their quantum correlations, and develops optimized hybrid communication protocols with near-perfect performance.

Findings

Analytical formulas for entanglement and discord in large displacements

Hybrid teleportation and remote state preparation protocols with high efficiency

Optimization over non-unitary operations improves protocol performance

Abstract

We investigate a family of qubit-oscillator states as resources for hybrid quantum communication. They result from a mechanism of qubit-controlled displacement on the oscillator. For large displacements, we obtain analytical formulas for entanglement and other nonclassical correlations, such as entropic and geometric discord, in those states. We design two protocols for quantum communication using the considered resource states, a hybrid teleportation and a hybrid remote state preparation. The latter, in its standard formulation, is shown to have a performance limited by the initial mixedness of the oscillator, echoing the behaviour of the geometric discord. If one includes a further optimization over non-unitary correcting operations performed by the receiver, the performance is improved to match that of teleportation, which is directly linked to the amount of entanglement. Both protocols can then approach perfect efficiency even if the oscillator is originally highly thermal. We discuss the critical implications of these findings for the interpretation of general quantum correlations.