Photon Blockade Effect Research Articles

Sideband‐Selective Single‐Photon Blockade in Floquet‐Modulated Jaynes–Cummings System

AbstractA circuit quantum electrodynamics (QED) scheme is proposed for generating an on‐demand single‐photon source with full external engineering in a Floquet‐modulated Jaynes–Cummings (JC) system. The photon blockade effect can be induced across multiple Floquet sidebands, enabling the selective generation of a bright single‐photon beam at a specific sideband frequency by adjusting the external driving field of the qubit, without requiring modifications to the circuit components. This is of significance for practical applications of integrated micro‐nano single quantum devices within a quantum information network.

Unconventional photon blockade in a nonlinear system embedded with an atom

Abstract The unconventional photon blockade effect due to quantum interference in a second-order nonlinear system embedded with a two-level atom is studied. By performing analytical calculations, the approximate results are obtained. By solving the master equation, the numerical calculation results are also obtained. Results show that the analytical results are consistent with the numerical results, which proves that unconventional photon blockade can be realized in this system. Furthermore, the effects of the system parameters on the unconventional photon blockade are also discussed. All the results may provide useful references for experimental investigations and practical applications of single-photon devices.

Nonreciprocal Unconventional Photon Blockade with Kerr Magnons

AbstractNonreciprocal devices, allowing to manipulate one‐way signals, are crucial to quantum information processing and quantum networks. Here a nonlinear cavity‐magnon system is proposed, consisting of a microwave cavity coupled to one or two yttrium–iron–garnet (YIG) spheres supporting magnons with Kerr nonlinearity, to investigate nonreciprocal unconventional photon blockade. The nonreciprocity originates from the direction‐dependent Kerr effect, distinctly different from previous proposals with spinning cavities and dissipative couplings. For a single sphere case, nonreciprocal unconventional photon blockade can be realized by manipulating the nonreciprocal destructive interference between two active paths, via varying the Kerr coefficient from positive to negative, or vice versa. By optimizing the system parameters, the perfect and well‐tuned nonreciprocal unconventional photon blockade can be predicted. For the case of two spheres with opposite Kerr effects, only reciprocal unconventional photon blockade can be observed when two cavity‐magnon coupling strengths Kerr strengths are symmetric. However, when coupling strengths or Kerr strengths become asymmetric, nonreciprocal unconventional photon blockade appears. This implies that two‐sphere nonlinear cavity‐magnon systems can be used to switch the transition between reciprocal and nonreciprocal unconventional photon blockades. This study offers a potential platform for investigating the nonreciprocal photon blockade effect in nonlinear cavity magnonics.

The photon blockade in a three-wave mixing system coupled with a quantum dot

In this paper, the photon blockade effect in a three-wave mixing coupling system with a quantum dot has been studied. By using analytical calculation and numerical analysis, we find that both the conventional photon blockade and the unconventional photon blockade effects could be realized in this system in strong-coupling regime just by one driving. Besides, compared with Jaynes–Cummings model, this hybrid system shows other obvious advantages in realizing the photon blockade, like blockading photon of more different frequencies, stronger antibunching effect. All the results may provide useful theoretical references for the single-photon devices design by using quantum dot and three-wave mixing system in future experiments and applications.

Achieving Strong Magnon Blockade through Magnon Squeezing in a Cavity Magnetomechanical System

AbstractA scheme that harnesses magnon squeezing under weak pump driving within a cavity magnomechanical system to achieve a robust magnon (photon) blockade is proposed. Through meticulous analytical calculations of optimal parametric gain and detuning values, the objective is to enhance the second‐order correlation function. The findings demonstrate a substantial magnon blockade effect under ideal conditions, accompanied by a simultaneous photon blockade effect. Impressively, both numerical and analytical results are found to be in complete accord, providing robust validation for the consistency of the findings. It is anticipated that the proposed scheme will serve as a pioneering approach toward the practical realization of magnon (photon) blockade in experimental cavity magnomechanical systems.

Phase-Controlled Tunable Unconventional Photon Blockade in a Single-Atom-Cavity System.

In the past few years, cavity optomechanical systems have received extensive attention and research and have achieved rapid development both theoretically and experimentally. The systems play an important role in many fields, such as quantum information processing, optomechanical storage, high-precision measurement, macroscopic entanglement, ultrasensitive sensors and so on. Photon manipulation has always been one of the key tasks in quantum information science and technology. Photon blockade is an important way to realize single photon sources and plays an important role in the field of quantum information. Due to the nonlinear coupling of the optical force system, the energy level is not harmonic, resulting in a photon blockade effect. In this paper, we study the phase-controlled tunable unconventional photon blockade in a single-atom-cavity system, and the second-order nonlinear crystals are attached to the cavity. The cavity interacts with squeezed light, which results in a nonlinear process. The system is driven by a complex pulsed laser, and the strength of the coherent driving contains the phase. We want to study the effect of squeezed light and phase. We use the second-order correlation function to numerically and theoretically analyze the photon blockade effect. We show that quantum interference of two-photon excitation between three different transition pathways can cause a photon blockade effect. When there is no squeezed light, the interference pathways becomes two, but there are still photon blockade effects. We explore the influence of the tunable phase and second-order nonlinear strength on the photon blockade effect. We calculate the correlation function and compare the numerical results with the analytical results under certain parameters and find that the agreement is better.

Unconventional photon blockade in the two-photon Jaynes–Cummings model with two-frequency cavity drivings and atom driving

In a two-frequency cavity driving and atom driving atom-cavity system, we find the photon blockade effect. In a truncated eigenstates space, we calculate the zero-delay second-order correlation function of the cavity mode analytically and obtain an optimal condition for the photon blockade. By including three transition pathways, we find that higher excitations of the cavity mode can be further suppressed and the zero-delay second-order correlation function can be reduced additionally. Based on the master equation, we simulate the system evolution and find that the analytical solutions match well with the numerical results. Our scheme is robust with small fluctuations of parameters and may be used as a new type of single photon source.

Fast optomechanical photon blockade

The photon blockade effect is commonly exploited in the development of single-photon sources. While the photon blockade effect could be used to prepare high-fidelity single-photon states in idealized regimes, practical implementations in optomechanical systems suffer from an interplay of competing processes. Here we derive a control scheme that exploits destructive interference of Fock state amplitudes of more than one photon. The resulting preparation time for photon-blockaded quantum states is limited only by the optomechanical interaction strength and can thus be orders of magnitude shorter than in existing schemes that achieve photon blockade in the steady state.

Conventional photon blockade in a four-wave mixing system with Kerr nonlinearity

We investigate conventional photon blockade in a non-degenerate four wave mixing system with Kerr non-linearity. By analyzing the Hamiltonian of the system, we have acquired the corresponding condition to implement photon anti-bunching effect. And we solve the master equation with the purpose of obtaining solutions numerically. We find that the analytic conditions could be consistent with numerical results, and photon blockade could be realized in this system. Furthermore, we discuss the effect of several parameters on the realization of conventional photon blockade in detail. The results show that four wave mixing interaction and Kerr non-linearity could significantly enhance the conventional photon blockade effect, whereas the dissipation rate has a negative effect on implementing photon blockade.

Antibunching Effects in the Hybrid Cavity–Bose–Einstein Condensates System

We theoretically study the model of a hybrid cavity–Bose–Einstein condensates (BEC) system that consists of a two-level impurity atom coupled to a cavity–BEC system with radiation pressure coupling, where the system is weakly driven by a monochromatic laser field. The steady-states behavior of the entire system is researched in the framework of the impurity–cavity coupling dispersive limit. We find that the multiple types of photon steady-state antibunching effects can be obtained when only the dissipation of the cavity is included. Moreover, the strength and frequency range of conventional steady-state antibunching effects of the cavity can be significantly modified by the impurity atom and intrinsic non-linearity of BEC. This result shows that our study can provide a method to tune the antibunching effects of the cavity field. In addition, the non-standard photon blockade or superbunching effect with the suppression of two-photon correlation and enhancement of three-photon correlation can be realized. The frequency range of the superbunching effect also can be changed by the impurity atom and intrinsic non-linearity of BEC. Therefore, our study shows many quantum statistical characteristics in a hybrid cavity–BEC quantum system and its manipulation.

Unconventional photon blockade in a non-Hermitian indirectly coupled resonator system.

Photon blockade provides an effective way to realize the single-photon source, which attracts intensive attention in the fields of quantum optics and quantum information. Here in this study, we investigate photon blockade in a non-Hermitian indirectly coupled resonator system, which consists of a dissipative cavity and a Kerr nonlinear resonator coupled to two nano-scatters. We find that by tuning the coupling phase θ between the two resonators, the quantum interference could be induced on one side near the exceptional points (EPs), resulting in the unconventional photon blockade effect. Furthermore, it is noticed that the large Kerr nonlinearity is not always beneficial for unconventional photon blockades. There is an optimal threshold for the intensity of the Kerr nonlinearity and the phase angle θ for the appearance of the unconventional photon blockade effect. We believe the current study has substantial consequences for investigating the physical characteristics close to EPs and presents a novel method for developing integrated on-chip single-photon sources.

Shot-noise-suppressing quantum nonlinearity in the vacuum-field-induced photon-photon interaction

The shot noise in coherent control of a quantum system sets an ultimate precision limit in measurement and information processing. It is caused by the fundamental quantum fluctuation of the photon number of a coherent control field and thus is inevitable. By strongly coupling a two-level system to a quantum vacuum field, we propose an effective $N$-type four-level system. In such a configuration, the coupling of a conventional $N$-type system to a coherent control field is replaced by the quantum vacuum field. As a result, we can achieve a shot-noise-suppressing quantum nonlinearity, due to the vanishing fluctuation of photon number of the quantum vacuum field. The resulting photon blockade effect is only subject to the contribution from the probe field. Thus, it becomes shot-noise suppressing. Our work shows an advantage of a quantum vacuum protocol over a coherent-field protocol in manipulation of quantum systems and presents an opportunity to exploit the quantum vacuum field as a powerful tool in quantum information processing.

Enhanced unconventional photon-blockade effect in one- and two-qubit cavities interacting with nonclassical light

The antibunching effect generated in a cavity containing first a single two-level atomic system and then two identical atoms is explored for off-resonant interactions, in strong- and weak-coupling regimes. The cavity is driven by coherent and squeezed sources. Using the second-order correlation function analytically derived in the weak-excitation regime, we show that squeezed light achieves and improves strong antibunching, leading to a photon blockade. This enhancement is due to a destructive quantum interference mechanism induced by the nonclassical light, creating a supplementary transition pathway. The best effect is obtained for equal frequency detunings in the strong-coupling regime. More interestingly, our investigation reveals that the two-atom-cavity system can further improve the antibunching effect compared to the single-atom cavity. It turns out that the additional couplings appearing in the cavity due to the implementation of the two atoms, combined with the squeezed light, could substantially enhance the photon-blockade effect.

Phase-controlled photon blockade in optomechanical systems

The manipulation of photons is a key technology for obtaining optical quantum information. In this study, we present a phase-modulated optomechanical system comprising two coupled cavity resonators and illustrate the phase-controlled photon blockade in the system. The coupling phase of the cavities reveals the interference of photons and introduces an unconventional photon-blockade effect. We also study the influence of the energy level fineness on the photon blockade and resonant frequency of the mechanical mode. Numerical simulations demonstrate that photon blockade can occur over a wide range of system parameters. These results have several implications for understanding the role of the state phase in quantum cavity optomechanics and provide a promising method for the realization of optomechanical quantum devices using photon blockade.

Retrieval of photon blockade effect in the dispersive Jaynes-Cummings model

We propose a reliable scheme to recover the conventional photon blockade effect in the dispersive Jaynes-Cummings model, which describes a two-level atom coupled to a single-mode cavity field in the large-detuning regime. This is achieved by introducing a transversal driving to the atom and then photonic nonlinearity is obtained. The eigenenergy spectrum of the system is derived analytically and the photon blockade effect is confirmed by numerically calculating the photon-number distributions and equal-time second-order correlation function of the cavity field in the presence of system dissipations. We find that the conventional photon blockade effect can be recovered at proper atomic and cavity-field drivings. This work will provide a method to generate the conventional photon blockade effect in the dispersively coupled quantum optical systems.

The photon blockade effect of a complete Buck-Sukumar model

The Buck-Sukumar (BS) model, with a nonlinear coupling between the atom and the light field, is well defined only when its coupling strength is lower than a critical coupling. Its energy collapses at a critical coupling and is unbounded beyond that value. In other words, the BS model is incomplete. We introduce a simple and a complete BS model by adding a nonlinear photon term into the initial BS model. Considering the rotating wave approximation, this complete BS model conserves the excited number and the parity. By expanding it in the subspace of the product state between the atom and the field, we solve the time-independent SchrÖdinger equation to obtain the eigenenergy and eigenstate. Furthermore, we explore the influence of the nonlinear photon term on the energy spectrum and the photon blockade effect for the complete BS model by calculating the excited number and second-order correlation function. Our study shows that, the nonlinear photon term not only eliminates the energy spectral collapse but also makes it well-defined and complete in all the coupling regime. When at the resonance between the atomic and the field frequency, the nonlinear photon term breaks the harmonicity of the energy spectrum and produces a ladder of the excited number in the ground state. Because the larger nonlinear photon term inhibits the photon transition from an energy level to the higher one, it produces the single-photon projection state in the larger coupling region. Accordingly, we find that the nonlinear photon term promotes photon blockade by calculating the second-order correlation function. When at the non-resonant region, the nonlinear photon term enlarges the originally anharmonic energy ladder. For a complete BS model with the fixed nonlinear photon coupling strength and the fixed detuning, the energy level for the positive detuning is lower than that with the negative detuning, and more energy is required to overcome the absorption of a photon. Therefore, the positive detuning promotes the photon blockade. For the negative detuning, the system is more likely to absorb a photon and jump to a higher energy level, and therefore, suppresses the photon blockade.

The photon blockade effect of a complete Buck-Sukumar model

<sec>The Buck-Sukumar (BS) model, with a nonlinear coupling between the atom and the light field, is well defined only when its coupling strength is lower than a critical coupling. Its energy collapses at a critical coupling and is unbounded beyond that value. In other words, the BS model is incomplete. We introduce a simple and complete BS model by adding a nonlinear photon term into the initial BS model. Considering the rotating wave approximation, this complete BS model conserves the excited number and the parity. By expanding it in the subspace of the product state between the atom and the field, we solve the time-independent Schrödinger equation to obtain the eigenenergy and eigenstate. Furthermore, we explore the influence of the nonlinear photon term on the energy spectrum and the photon blockade effect for the complete BS model by calculating the excited number and second-order correlation function.</sec><sec>Our study shows that, the nonlinear photon term not only eliminates the energy spectral collapse but also makes it well-defined and complete in all the coupling regime. When at the resonance between the atomic and the field frequency, the nonlinear photon term breaks the harmonicity of the energy spectrum and produces a ladder of the excited number in the ground state. Because the larger nonlinear photon term inhibits the photon transition from an energy level to the higher one, it produces the single-photon projection state in the larger coupling region. Accordingly, we find that the nonlinear photon term promotes photon blockade by calculating the second-order correlation function. When at the non-resonant region, the nonlinear photon term enlarges the originally anharmonic energy ladder. For a complete BS model with the fixed nonlinear photon coupling strength and the fixed detuning, the energy level for the positive detuning is lower than that with the negative detuning, and more energy is required to overcome the absorption of a photon. Therefore, the positive detuning promotes the photon blockade. For the negative detuning, the system is more likely to absorb a photon and jump to a higher energy level, and therefore, suppresses the photon blockade.</sec>

Improving few-photon optomechanical effects with coherent feedback.

Few-photon effects such as photon blockade and tunneling have potential applications in modern quantum technology. To enhance the few-photon effects in an optomechanical system, we introduce a coherent feedback loop to cavity mode theoretically. By studying the second-order correlation function, we show that the photon blockade effect can be improved with feedback. Under appropriate parameters, the photon blockade effect exists even when cavity decay rate is larger than the single-photon optomechanical coupling coefficient, which may reduce the difficulty of realizing single-photon source in experiments. Through further study of the third-order correlation function, we show that the tunneling effect can also be enhanced by feedback. In addition, we discuss the application of feedback on Schrödinger-cat state generation in an optomechanical system. The result shows that the fidelity of cat state generation can be improved in the presence of feedback loop.

Nonreciprocal photon blockade in a spinning optomechanical resonator

A scheme is presented to realize nonreciprocal photon blockade by exploiting a spinning optomechanical resonator, where the photon blockade effect appears when the spinning resonator is driven from one side but vanishes from the other side. This quantum nonreciprocity originates from the Sagnac effect and Kerr-type interaction between photons in the spinning resonator. We analyze the dynamics of the system in the weak driving regime, and discuss the photon statistical properties by calculating the second-order correlation function. Based on master-equation simulations, we also study numerical results of the steady state of the system and the validity of the analytical solution, and find that it is feasible to achieve nonreciprocal photon blockade by choosing appropriate parameters in a spinning optomechanical resonator.

Optical normal-mode-induced phonon-sideband splitting in the photon-blockade effect

We study the photon-blockade effect in a loop-coupled optomechanical system consisting of two cavity modes and one mechanical mode. Here, the mechanical mode is optomechanically coupled to the two cavity modes, which are coupled with each other via a photon-hopping interaction. By treating the photon-hopping interaction as a perturbation, we obtain the analytical results of the eigenvalues and eigenstates of the system in the subspaces associated with zero, one, and two photons. We find a phenomenon of optical normal-mode-induced phonon-sideband splitting in the photon-blockade effect by analytically and numerically calculating the second-order correlation functions of the two cavity modes. This work not only presents a method to choose optimal driving frequency for photon blockade by tuning the photon-hopping interaction, but also provides a means to characterize the normal-mode splitting with cavity photon statistics.