We theoretically study the photon blockade (PB) effect in a double-cavity optomechanical system with the two-photon driving. By analytical calculations and numerical simulations, the physical mechanisms of conventional photon blockade (CPB) and unconventional photon blockade (UPB) are discussed in detail. And then we obtain the optimal parameter conditions for PB. In our work, there exist both the CPB induced by strong nonlinear interaction and the UPB caused by quantum interference. In particular, we find that CPB and UPB can occur simultaneously under the same parameters. In addition, we also prove that the appropriate values of nonreciprocal coupling and two-photon driving are favorable to the improvement of PB. Our proposal provides an idea for simultaneously realizing CPB and UPB in the optomechanical system and offers a route for constructing high-quality single-photon sources.
We theoretically study the photon blockade (PB) effect in a double-cavity optomechanical system with the two-photon driving. By analytical calculations and numerical simulations, the physical mechanisms of conventional photon blockade (CPB) and unconventional photon blockade (UPB) are discussed in detail. And then we obtain the optimal parameter conditions for PB. In our work, there exist both the CPB induced by strong nonlinear interaction and the UPB caused by quantum interference. In particular, we find that CPB and UPB can occur simultaneously under the same parameters. In addition, we also prove that the appropriate values of nonreciprocal coupling and two-photon driving are favorable to the improvement of PB. Our proposal provides an idea for simultaneously realizing CPB and UPB in the optomechanical system and offers a route for constructing high-quality single-photon sources.
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.
Photon blockade (PB), an effective method of generating antibunching effect, is a critical way to construct a single photon source. The PB effect can be divided into conventional PB effect (CPB) and unconventional PB effect (UPB). Most studies focus on designing systems to successfully enhance CPB or UPB effect individually. However, CPB extremely depends on the nonlinearity strength of the Kerr materials to achieve strong antibunching effect while UPB relies on quantum interference beset with the high probability of the vacuum state. Here, we propose a method to utilize the relevance and complementarity of CPB and UPB to realize these two types simultaneously. We employ a hybrid Kerr nonlinearity two-cavity system. Because of the mutual assistance of two cavities, CPB and UPB can coexist in the system under certain states. In this way, for the same Kerr material, we reduce the value of the second-order correlation function due to CPB by three orders of magnitude without losing the mean photon number due to the presence of UPB, so the advantages of both PB effects are fully reflected in our system, which is a huge performance boost for single photons.
Abstract In this paper, conventional phonon blockade (CPNB) and conventional photon blockade (CPTB) effects, as well as unconventional phonon blockade (UPB) effects, are studied in an optomechanical system with nonlinear interaction between the cavity frequency and the square of the mechanical displacement driven by an external field, where a two‐level atom couples with the mechanical mode and a microwave driving field pumps cavity mode. The second‐order correlation function is analytically calculated, which is in good agreement with the numerical simulation given by the master equation. With energy‐level diagram, the atom‐mechanical mode coupling is found to induces the degeneracy splitting of the states and give the optimal conditions for CPNB and CPTB in this system. With the origin of UPB, the optimal conditions are derived and it is found that the realization of UPB is determined by the two couplings of the cavity and atom with respect to the mechanical mode. Moreover, some discussions on the experimental implementation in this quadratically coupled optomechanical system are presented. This study provides a possible way for realizing single‐photon nonlinearity and can extend the applications of optomechanical systems in the field of quantum optics.
The research article studies the unconventional photon blockade effect in a hybrid optomechanical system with an embedded spin-triplet state. The interaction between the optomechanical system and the spin state generates new transition paths for the destructive quantum interference of the two-photon excitation state. By analytically solving the Schrodinger equation and numerically simulating the master equation, it can be found that the modulated mechanical dissipation is essential for achieving the strong photon blockade in our system. Unlike the conventional cavity optomechanical system, the second-order correlation function g(2)(0) =0 can be obtained with the weak single-photon optomechanical coupling. By adjusting the system parameters, the strong photon blockade and the single-photon resonance can coincide, which indicates the hybrid system has the potential to be a high-quality and efficient single-photon source. Finally, the influence of the thermal noise on photon blockade is investigated. The results show that the second-order correlation function is more robust for the weaker phonon-spin coupling.
In this paper, we show that the photon blockade (PB) can be observed in a nonreciprocal way with a driven spinning atom-cavity coupled filled with [Formula: see text] nonlinear medium. We analytically derive the optimal conditions for strong photon antibunching, which are in good agreement with those obtained by numerical simulations. Under the weak driving condition, we discuss the physical origins of the nonreciprocal unconventional photon blockade (UPB), which originates from the destructive quantum interference between different paths from the ground state to two-photon states by driving the device from the left side. While the quantum interference paths are broken when the device is driven from the right side, which leads to the occurrence of the photon bunching. Moreover in the opposite direction of driving the device, we also observe another nonreciprocal UPB effect, which can occur by generating bunching and antibunching effects via driving the device from the left and right sides under the derived optimal conditions, respectively. Finally, we cannot observe the nonreciprocal UPB phenomenon with the large cavity decay compared to the atomic spontaneous emission rate (or the bad cavity limit), and give the physical reason behind it. Possible experimental implementation for this scheme is presented.
Abstract Unconventional photon blockade (UPB) is an important quantum phenomenon that relies on the quantum interference effect. Here, we propose coupling an optical parametric amplifier (OPA) to a Kerr nonlinear single-mode cavity in a two-photon dissipation environment, enabling strong photon antibunching based on the UPB mechanism. The optimal conditions for achieving UPB are first derived analytically. The results are subsequently compared with the second-order correlation function derived from numerical simulations, and excellent agreement is observed. The findings show that UPB is enhanced without significantly reducing the mean photon number. This further demonstrates that the width of the UPB occurrence window increases with increasing OPA coefficient and driving laser intensity. Finally, theoretical analysis reveals the physical mechanism of UPB, showing that the Kerr medium is not the dominant factor for UPB generation in this system. Thus, our work offers valuable theoretical guidance for precisely controlling UPB and optimizing single-photon source performance.