Photon blockade in two-emitter-cavity systems

Abstract

The photon blockade (PB) effect in emitter-cavity systems depends on the anharmonicity of the ladder of dressed energy eigenstates. The recent developments in color center photonics are leading toward experimental demonstrations of multi-emitter-cavity solid-state systems with an expanded set of energy levels compared to the traditionally studied single-emitter systems. We focus on the case of N = 2 nonidentical quasi-atoms strongly coupled to a nanocavity in the bad cavity regime (with parameters within reach of the color center systems), and discover three PB mechanisms: polaritonic, subradiant and unconventional. The polaritonic PB, which is the conventional mechanism studied in single-emitter-cavity systems, also occurs at the polariton frequencies in multi-emitter systems. The subradiant PB is a new interference effect owing to the inhomogeneous broadening of the emitters which results in a purer and a more robust single photon emission than the polaritonic PB. The unconventional PB in the modeled system corresponds to the suppression of the singleand two-photon correlation statistics and the enhancement of the three-photon correlation statistic. Using the effective Hamiltonian approach, we unravel the origin and the time-domain evolution of these phenomena.Introduction-While an arbitrary number of photons can populate a bare nanocavity, the paradigm changes with the introduction of a strongly coupled dipole emitter. The photon blockade (PB) effect prevents the absorption of the second photon at specific frequencies due to the nonlinearity of the emitter that dresses the energy states and leads to an anharmonic ladder. This effect has been extensively studied in single-emitter (N = 1) atomic [1, 2] and quantum dot [3,4] cavity quantum electrodynamics (CQED), as well as in circuit QED systems [5]. Here, the effect occurs at the frequencies of the dressed states so-called polaritons (polaritonic PB) and results in a faster emission rate of single photons compared to the bare emitter. Experimentally, a signature of single photon emission has been the reduced value of the second order coherence g (2) (0) < 1. A recent paper has contested this criterion [6], demonstrating conditions for the so-called unconventional photon blockade where the twophoton statistic is suppressed, but the enhanced higher order coherences strengthen the generation of multiple photons. A cavity coupled to multiple (N 1) emitters would offer a richer set of dressed states and extend new opportunities for nonclassical light generation with applications in quantum key distribution [7], quantum metrology [8] and quantum computation [9]. Moreover,

Nonreciprocal unconventional photon blockade in a spinning optomechanical system

“…A good singlephoton source is characterized not only by g (2) (0) ≈ 0, but also by vanishing higher-order photon-number correlation functions, g (n) (0) ≈ 0 for n > 2. In UPB, g (n) (0) for n > 2 can be greater than g (2) (0) ≈ 0, or even greater than 1 [95]. Indeed a standard analytical method for analyzing UPB, as proposed by Bamba et al [24] and applied here, is based on expanding the wave function |ϕ of a two-resonator system in power series |ϕ = C n,m |n, m up to the terms Cn, 2 − n (n = 0, 1, 2) only, as given in Eq.…”

Tunable Photon Statistics Exploiting the Fano Effect in a Waveguide

“…A coherent input state can be considered as a weighted sum of different number states [8]. Number-state filtering, in which the weighting of the individual number states is controlled, can generate a quantum output state from such a classical coherent input (for instance, via photon blockade [9][10][11][12][13]). The use of interference has emerged as an extremely powerful tool in this regard: it has been shown theoretically that it can be used to realize complex photon statistics in cavity [14][15][16] and waveguide [17,18] quantum electrodynamics (QED), and to generate single photons with simultaneous subnatural linewidth using resonance fluorescence [19].…”

Unconventional photon blockade

“…Contrary to what is commonly believed, small nonlinear energy shifts are actually a sufficient ingredient to build up sizable quantum correlations even under weak driving [22]. The key requirement is to couple at least two degrees of freedom in order to assist quantum interferences between excitation pathways [23][24][25][26][27]. In that framework, a strongly sub-Poissonian statistics can be achieved by means of a pair of driven dissipative resonators with an arbitrarily small single photon nonlinearity.…”