Stationary two-qubit entanglement mediated by one-dimensional plasmonic nanoarrays

TL;DR

This study explores how one-dimensional plasmonic nanoarrays can mediate and sustain stationary entanglement between two quantum dot qubits over long distances, revealing array size and configuration effects on entanglement robustness.

Contribution

It introduces an effective cavity QED model to analyze long-range qubit entanglement mediated by metal nanoparticle arrays, highlighting the enhanced robustness in odd-number arrays.

Findings

Odd-number nanoparticle arrays are more robust to entanglement decay.

Arrays can sustain entanglement beyond one micron spacing.

Hybridized plasmon resonances enhance inter-qubit coupling.

Abstract

Entanglement is one of the key measures of quantum correlations present in nanophotonic systems, with promising applications in quantum optics and beyond. Previous studies have shown that the degree of entanglement between two quantum dot qubits is preserved when a metal nanoparticle is used to mediate the interactions between the qubits. In this work, we investigate long-range plasmonic mediation of qubit--qubit entanglement by studying the impact of the number of mediating metal nanoparticles on stationary concurrence. Collinear and periodically spaced metal nanoparticles that satisfy the weak-coupling approximation are considered. An effective model that enables the derivation of the mediated interactions within the framework of cavity quantum electrodynamics is employed. Under weak driving at the single particle resonance frequency, the model shows that odd-number arrays are more robust to entanglement decay. We attribute this to strong inter-qubit dissipative coupling as a result of a hybridized dipole plasmon resonating with the driving frequency in odd-number arrays. These arrays can sustain non-vanishing stationary entanglement beyond an inter-qubit spacing of one micron, opening up the possibility of independent spatial optical probing of each quantum dot.