Steady-state entanglement between distant quantum dots in photonic crystal dimers

TL;DR

This paper demonstrates that two distant semiconductor quantum dots can achieve strong, steady-state entanglement mediated by photonic crystal dimers, with robustness against inhomogeneity and dephasing, promising for quantum information applications.

Contribution

It introduces a method to generate and analyze steady-state entanglement between distant quantum dots via photonic crystal dimers, considering realistic parameters and robustness factors.

Findings

Negativity of 0.1 achieved at large interdot distances

Entanglement is robust to quantum dot detuning and dephasing

Transient entanglement can be significantly enhanced over steady-state

Abstract

We show that two spatially separated semiconductor quantum dots under resonant and continuous-wave excitation can be strongly entangled in the steady-state, thanks to their radiative coupling by mutual interaction through the normal modes of a photonic crystal dimer. We employ a quantum master equation formalism to quantify the steady-state entanglement by calculating the system {\it negativity}. Calculations are specified to consider realistic semiconductor nanostructure parameters for the photonic crystal dimer-quantum dots coupled system, determined by a guided mode expansion solution of Maxwell equations. Negativity values of the order of 0.1 ($20\%$ of the maximum value) are shown for interdot distances that are larger than the resonant wavelength of the system. It is shown that the amount of entanglement is almost independent of the interdot distance, as long as the normal mode splitting of the photonic dimer is larger than their linewidths, which becomes the only requirement to achieve a local and individual qubit addressing. Considering inhomogeneously broadened quantum dots, we find that the steady-state entanglement is preserved as long as the detuning between the two quantum dot resonances is small when compared to their decay rates. The steady-state entanglement is shown to be robust against the effects of pure dephasing of the quantum dot transitions. We finally study the entanglement dynamics for a configuration in which one of the two quantum dots is initially excited and find that the transient negativity can be enhanced by more than a factor of two with respect to the steady-state value. These results are promising for practical applications of entangled states at short time scales.