Tunable bandwidth and nonlinearities in an atom-photon interface with subradiant states

Abstract

Optical non-linearities at the single photon level are key features to build efficient photon-photon gates and to implement quantum networks. Such optical non-linearities can be obtained using an ideal two-level system such as a single atom coupled to an optical cavity. While efficient, such atom-photon interface however presents a fixed bandwidth, determined by the spontaneous emission time and thus the spectral width of the cavity-enhanced two-level transition, preventing an efficient transmission to bandwidth-mismatched atomic systems in a single quantum network. In the present work, we propose a tunable atom-photon interface making use of the direct dipole-dipole coupling of two slightly different atomic systems. We show that, when weakly coupled to a cavity mode and directly coupled through dipole-dipole interaction, the subradiant mode of two slightly-detuned atomic systems is optically addressable and presents a widely tunable bandwidth and single-photon nonlinearity.arXiv:1807.04105v1 [quant-ph]

Time-frequency encoded single-photon sources and broadband quantum memories based on a tunable one-dimensional atom

“…We hereafter introduce an effective one dimensional atom where the system bandwidth and mode coupling are largely independent. We consider the system consisting of two atoms represented by two level systems (TLS) strongly coupled through a dipole-dipole interaction and coupled to the same cavity mode [22]. The TLS have ground states |g i and excited states |e i (i = 1, 2), with transition energies E |ei − E |gi = ω i and a dipole-dipole coupling strength Ω 12 [19].…”

“…1, ∆ 12 acts as an effective coupling between the states |+ and |− . The system eigenstates |− eff and |+ eff are then a superposition of both symmetric and antisymmetric states for which simple analytical expressions can be obtained when γ Ω 12 , g [22]:…”

“…We consider the system made of two atoms mutually coupled through dipolar interaction [19][20][21] and coupled to the same cavity mode. In the bad cavity limit, the eigenstates are superpositions of sub-radiant and superradiant states with controllable weight [22]. Remarkably, while the eigenstates present bandwidth tunability, their coupling to the cavity remains mostly constant.…”

Photon correlations in the collective emission of hybrid gold-(CdSe/CdS/CdZnS) nanocrystal supraparticles

“…They allow to confine and tune the electromagnetic field at subwavelength scales. The plasmonic mode can play a crucial role, mediating and adjusting the coupling in the near field [15][16][17]. This approach can also be extended to obtain phase locking between 2D arrays of spasers [18].…”

Perfect Photon Indistinguishability from a Set of Dissipative Quantum Emitters

“…Recently, theoretical studies [34][35][36][37][38] have shown that the enhancement and tunability of single photon emission are possible through interfaces based on two-emitter systems coupled to a cavity mode. In their scheme, tunable bandwidth and Purcell enhancement are achieved by dynamical control of the collective states of the two emitters coupled by dipolar interaction.…”