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

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 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.

Signatures of single-photon interaction between two quantum dots located in different cavities of a weakly coupled double microdisk structure

“…Using PMs to obtain an efficient coupling between the QDs presents an integrable and compact semiconductor solution. In addition, these PMs have also been theoretically investigated for entanglement of a pair of QDs [12,13], they enable the unconventional photon blockade [14,15], and serve as a starting point for the realization of driven-dissipative multi-cavity systems [16] and strong photon-photon correlations [17][18][19].An attractive type of cavity systems are whispering gallery mode (WGM) supporting microdisks (see exemplary SEM-picture in Fig. 1 a)).…”

Disorder effects on the coupling strength of coupled photonic crystal slab cavities

“…δJ/ J ≪ 1. The present results are of particular relevance for the design of state-of-the-art integrated PhC devices and for the rapidly growing research on quantum many-body phenomena in photonic arrays [35,36,37,38,39,40].…”

“…J J 1 d á ñ  . The present results are of particular relevance for the design of state-of-the-art integrated PhC devices and for the rapidly growing research on quantum many-body phenomena in photonic arrays [35][36][37][38][39][40].The paper is organized as follows. In section 2 we discuss the resonant modes of the ideal (i.e.…”

Steady State Entanglement beyond Thermal Limits

“…More generally, optical pumping schemes are used to selectively prepare and maintain the working medium in a given non-trivial target steady state that is different from its thermal equilibrium state. In this spirit, the potential of achieving steady state entanglement of pairs of qubits through quantum optical bath engineering has started to be explored [3][4][5][6][7][8][9][10][11][12][13][14][15][16] , most of the attention being focused on thermal baths as purely incoherent sources of non classical correlations [17][18][19][20][21][22] ; however, for the latter protocols the amount of entanglement that can be generated without any additional feedback or filtering operation is typically rather modest 21,22 . By using reservoirs acting on collective degrees of freedom of the qubits, the upper theoretical limit for the concurrence can be increased to C = 1/3, which is asymptotically reached only under unrealistically large temperature gradients between the two reservoirs 17,19 .…”