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arXiv:2112.14227 · New Journal of Physics

Single-photon blockade in quasichiral atom–photon interaction: simultaneous high purity and high efficiency

Yuwei Lu, Jingfeng Liu, Runhua Li, Yanxiong Wu, Haishu Tan, Yongyao Li

Published Apr 25, 2022• 10 citations
arXivHTMLPDF

Abstract

Abstract We investigate the single-photon blockade (1PB) in the quasichiral regime of atom–photon interaction, where the effective coupling between the cavity and the atom is bidirectional but asymmetrical, achieved by coupling to a dissipative environment. A synthetic magnetic current ϕ is induced in the closed-loop coupling, which breaks down the reciprocity of atom–photon interaction, and can be utilized to create asymmetrical or even unidirectional effective coupling between two selected quantum states. As an example, we couple the single-atom cavity quantum electrodynamics (QED) system to a strongly dissipative plasmonic cavity. We find that in the quasichiral regime, the unconventional photon blockade (UPB) and the conventional photon blockade (CPB) realize simultaneously in the condition of maximum chirality (ϕ = π/2 and 3π/2). As a result, 1PB in the quasichiral regime can combine the advantages of both UPB and CPB, demonstrating the perfect single-photon purity, higher efficiency, non-oscillating time dynamics as well as lower requirement of mode coupling to achieve UPB. Our work paves the way for 1PB towards practical applications and reveals the intriguing quantum-optics phenomena in the quasichiral light–matter interaction.

DOI
10.1088/1367-2630/ac6a46

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Abstract We investigate the single-photon blockade (1PB) in the quasichiral regime of atom–photon interaction, where the effective coupling between the cavity and the atom is bidirectional but asymmetrical, achieved by coupling to a dissipative environment. A synthetic magnetic current ϕ is induced in the closed-loop coupling, which breaks down the reciprocity of atom–photon interaction, and can be utilized to create asymmetrical or even unidirectional effective coupling between two selected quantum states. As an example, we couple the single-atom cavity quantum electrodynamics (QED) system to a strongly dissipative plasmonic cavity. We find that in the quasichiral regime, the unconventional photon blockade (UPB) and the conventional photon blockade (CPB) realize simultaneously in the condition of maximum chirality (ϕ = π/2 and 3π/2). As a result, 1PB in the quasichiral regime can combine the advantages of both UPB and CPB, demonstrating the perfect single-photon purity, higher efficiency, non-oscillating time dynamics as well as lower requirement of mode coupling to achieve UPB. Our work paves the way for 1PB towards practical applications and reveals the intriguing quantum-optics phenomena in the quasichiral light–matter interaction.
We theoretically investigate the quantum-interference-induced photon blockade effect in a single two-level atom-cavity quantum electrodynamics (QED) system with degenerate parametric amplification. The analytical calculations reveal the optimal parametric gain and phase parameters for achieving optimum unconventional photon blockade conditions. Under the optimal parameter regime, the numerical results of the second-order correlation function demonstrate strong photon antibunching consistent with the analytical results. Furthermore, the numerical results corroborate that coherently driving the atom leads to a stronger photon blockade than a coherently driven cavity with the optimal parameters. We numerically demonstrate that the UPB effect is compromised by a non-zero cavity-atom coupling in the cavity-driven configuration. However, stronger photon antibunching can be attained with a non-zero cavity-atom coupling in the atom-driven configuration. This work may be suitable for experimentally realising a strongly antibunched single-photon source for applications in quantum technology.
We introduce a method to achieve nonreciprocal photon blockade in an optical resonator that is chirally coupled to a two-level atom. This approach enables single-excitation and two-excitation resonant conditions to be simultaneously satisfied. The atom-uncoupled optical mode can be blocked with eliminating its two-photon excitation by judiciously selecting parameters, e.g., the optical coupling strength. The chiral interaction between the resonator mode and the atom leads to different optimal parameter conditions for generating photon blockade in the two opposite drivings. This offers a natural way to realize nonreciprocal photon blockade. The nonreciprocity achieved by the chiral cavity-atom interaction diminishes the experimental difficulty by eliminating the need to rotate the resonator. The blockade mode achieves very high purity of single-photon excitation, as characterized by a second-order correlation function of ${g}^{(2)}(0)\ensuremath{\sim}{10}^{\ensuremath{-}4}$. In particular, in the nonreciprocal regime, the mean number of photons is significantly higher where photon blockade occurs compared to the general Jaynes-Cummings case. Our findings are particularly relevant for the development of quantum nonreciprocal devices and their applications in quantum information processing, including chiral networks.
Photon blockade is vital for single-photon generation, but current schemes with conventional and unconventional photon blockade face critical limitations like the purity-brightness trade-off, hindering the generation of high-performance single-photons. To overcome these limitations, we introduce a fundamentally new photon blockade mechanism by utilizing three-body interactions between a single photonic mode and two qubits. This kind of interaction intrinsically cuts off the excitation path to the two-photon state, resulting in a perfect photon blockade effect. The mechanism operates across a broad parameter range, free from the constraints of strong coupling or weak driving. Remarkably, it breaks the purity-brightness trade-off, enabling the simultaneous achievement of extreme purity and high brightness, both significantly outperforming previous mechanisms. Furthermore, this approach demonstrates robustness against thermal noise and avoids unwanted oscillations in the time-delayed correlation function. This work provides a path for generating high-purity, high-brightness, and robust single-photon sources, a key resource for quantum technologies.
Abstract Quantum information processing, a key component of quantum information science, has attracted considerable attention. Its realization requires physical platforms and resources, among which optical systems and single-photon sources based on photon blockade (PB) have been widely employed. Here we investigate PB behaviors in a coupled optical cavity system driven by both single- and two-photon fields. The optimal conditions for PB are obtained with respect to the two-photon driving strength and cavity-laser detuning via analytical calculations. Using these optimal solutions, we show that a significant PB effect is achievable even with weak Kerr nonlinearity, and confirm that this behavior corresponds to unconventional PB (UPB) through a comparison of the second- and third-order correlation functions. Furthermore, our analysis reveals that UPB can be enhanced by two-photon dissipation. These results provide theoretical strategies for enhancing UPB, and offer insight into its fundamental mechanism.
Abstract We have investigated the unconventional photon blockade (UPB) in a hybrid system consisting of a Jaynes–Cummings model nonlinearly coupled with two other modes via a three-wave mixing interaction, operating in the weak coupling regime (compared with the decay rates of the system). We present both analytical and numerical results, obtained by solving the Schrödinger equation and the quantum master equation, respectively. The results show that the numerical simulations agree well with the analytical predictions and that the UPB effect would occur in this hybrid system both in the cavity-driven and atom-driven conditions. Under both driving conditions, the hybrid system could exhibit superior performance over the Jaynes–Cummings model under the same driving condition, i.e. achieve a stronger photon blockade effect. The influences of driving strength and coupling coefficient on photon blockade effect have also been discussed. Our finding may have potential applications in single-photon sources design.
A high-quality single-photon blockade system can effectively enhance the quality of single-photon sources. Conventional photon blockade(CPB) suffers from low single-photon purity and high requirements for system nonlinearity, while unconventional photon blockade(UPB) has the disadvantage of low brightness. Recent research by [Laser Photon.Rev 14,1900279,2020] demonstrates that UPB can be used to enhance the strength of CPB, thereby improving the purity of single-photon sources. Research by [Opt. Express 30(12),21787,2022] shows that there is an intersection point between CPB and UPB in certain nonlinear systems, where the performance of single photons is better. In this study, we investigated the phenomenon of photon blockade in a non-degenerate four-wave mixing system, where CPB and UPB can occur simultaneously within the same parameter range. We refer to this phenomenon as composite photon blockade. Particularly, when the system achieves composite photon blockade, the value of g(2)(0) is smaller, and there are more single photons. We conducted analytical analysis and numerical calculations to study the conditions for the realization of CPB, UPB, and 2PB in the system, and discussed in detail the influence of system parameters on various blockade effects.