Antibunching and entanglement play important roles in quantum information processing as antibunching is an essential ingredient for the production of single photons (phonons) and entanglement is a crucial resource for quantum communication and metrology. In this paper, we propose a atom-photon-phonon (tripartite) interaction in a hybrid cavity-atom-mechanics system, and show that both photon and phonon antibunching can be observed simultaneously under the resonant atomic driving. More importantly, the generated single photons and phonons are strongly correlated and entangled with each other, i.e., single entangled photon-phonon pairs are generated via the atom-photon-phonon interaction. The generation of single entangled photon-phonon pairs is the first step to implement entanglement-based quantum state transfer, which is essential for connecting mechanical and optical systems to build hybrid quantum networks.
Antibunching and entanglement play important roles in quantum information processing as antibunching is an essential ingredient for the production of single photons (phonons) and entanglement is a crucial resource for quantum communication and metrology. In this paper, we propose a atom-photon-phonon (tripartite) interaction in a hybrid cavity-atom-mechanics system, and show that both photon and phonon antibunching can be observed simultaneously under the resonant atomic driving. More importantly, the generated single photons and phonons are strongly correlated and entangled with each other, i.e., single entangled photon-phonon pairs are generated via the atom-photon-phonon interaction. The generation of single entangled photon-phonon pairs is the first step to implement entanglement-based quantum state transfer, which is essential for connecting mechanical and optical systems to build hybrid quantum networks.
Phonon nonlinearities play an important role in hybrid quantum networks and on-chip quantum devices. We investigate the phonon statistics of a mechanical oscillator in hybrid systems composed of an atom and one or two standard optomechanical cavities. An efficiently enhanced atom-phonon interaction can be derived via a tripartite atom-photon-phonon interaction, where the atom-photon coupling depends on the mechanical displacement without practically changing a cavity frequency. This novel mechanism of optomechanical interactions, as predicted recently by Cotrufo et al. [Phys. Rev. Lett. 118, 133603 (2017)], is fundamentally different from standard ones. In the enhanced atom-phonon coupling, the strong phonon nonlinearity at a single-excitation level is obtained in the originally weak-coupling regime, which leads to the appearance of phonon blockade. Moreover, the optimal parameter regimes are presented both for the cases of one- and two- cavities. We compared phonon-number correlation functions of different orders for mechanical steady states generated in the one-cavity hybrid system, revealing the occurrence of phonon-induced tunneling and different types of phonon blockade. Our approach offers an alternative method to generate and control a single phonon in the quantum regime, and has potential applications in single-phonon quantum technologies.
Phonon nonlinearities play an important role in hybrid quantum networks and on-chip quantum devices. We investigate the phonon statistics of a mechanical oscillator in hybrid systems composed of an atom and one or two standard optomechanical cavities. An efficiently enhanced atom-phonon interaction can be derived via a tripartite atom-photon-phonon interaction, where the atom-photon coupling depends on the mechanical displacement without practically changing a cavity frequency. This novel mechanism of optomechanical interactions, as predicted recently by Cotrufo et al. [Phys. Rev. Lett.118, 133603 (2017)10.1103/PhysRevLett.118.133603], is fundamentally different from standard ones. In the enhanced atom-phonon coupling, the strong phonon nonlinearity at a single-excitation level is obtained in the originally weak-coupling regime, which leads to the appearance of phonon blockade. Moreover, the optimal parameter regimes are presented both for the cases of one and two cavities. We compared phonon-number correlation functions of different orders for mechanical steady states generated in the one-cavity hybrid system, revealing the occurrence of phonon-induced tunneling and different types of phonon blockade. Our approach offers an alternative method to generate and control a single phonon in the quantum regime and could have potential applications in single-phonon quantum technologies.
Abstract We introduce a hybrid cavity optomechanical model capable of generating significant genuine tripartite interactions and entanglement among coherent degrees of freedom. However, realizing and controlling such tripartite interactions and their entanglement pose crucial challenges that remain largely unexplored. In this work, we predict a tripartite coupling mechanism within a hybrid quantum system consisting of a vibrating mechanical oscillator, a two-level atom and a single-frequency cavity field. We specifically propose a mechanism for tripartite and cross-Kerr nonlinear coupling through displacement and squeezing transformations. By adjusting the optical amplitude of the pump light, we can effectively enhance these nonlinear couplings, facilitating the manipulation of entangled and squeezed states. The resulting tripartite genuine entanglement exhibits distinct evolutionary characteristics. Notably, when the pump light amplitude is large, the tripartite entanglement persists for longer time. Additionally, the phonon displays characteristics of both cooling and squeezing. Our study presents a pathway for exploring and exploiting controllable multipartite entanglement, as well as achieving phonon cooling and squeezing with the assistance of a mesoscopic harmonic oscillator. This work underscores the innovative potential of our model in advancing the field of optomechanics and quantum entanglement.
The coherent control of single-photon emitters as, e.g., single ions or atoms, is a crucial element for mapping quantum information between light and matter. The possibility of generating entanglement between a photon and the emitter system provides an interface between matter-based quantum memories and photonic quantum communication channels, which is the essential resource for quantum repeaters and other future quantum information applications. To generate entangled atom-photon states, in our experiment, we store a single 87 Rb atom in an optical dipole trap. The single-atom/single-photon character is confirmed by the observation of photon antibunching in the detected fluorescence light. The spectral properties of single photons emitted by the atom allowed us to determine the mean kinetic energy of the atom corresponding to 105 μK. We describe a single-atom state analysis method which allowed us to characterize the entanglement between the atom and a single photon emitted in the spontaneous decay. We obtain an entanglement fidelity of 89% that clearly shows the high degree of entanglement in our system and potential for further applications in quantum communication.
Engineering atom-atom interactions is essential both for controlling novel phases of matter and for efficient preparation of many-body entangled states, which are key resources in quantum communication, computation, and metrology. In this work, we propose a scheme to tailor these interactions by coupling driven atom pairs to optical cavity photons via a molecular state in the dispersive regime, resulting in an effective photon-field-dependent potential. As an illustrative example, by analyzing the quantum Fisher information, we show that such induced interactions can generate robust many-body entanglement in two-mode ultracold bosons in an optical cavity. By tuning the photon-induced interactions through the cavity drive, we identify conditions for preparing highly entangled states on timescales that mitigate decoherence due to photon loss. Our results show that entanglement formation rate scales strongly with both photon and atom number, dramatically reducing the timescale compared to bare atomic interactions. We also identify an optimal measurement for exploiting the metrological potential of the atomic state in an interferometric protocol with significant photon losses, saturating the quantum Cramer-Rao lower bound. Furthermore, we show that despite these losses the atomic state exhibits strong Bell correlations. Our results pave the way for engineering atom-atom interactions to study novel phases of light and matter in hybrid atom-photon systems, as well as for tailoring complex quantum states for new quantum technology protocols and fundamental tests of quantum mechanics.
Efficient generation of multiquanta emission is crucial for quantum information processing but remains challenging due to its typical reliance on higher-order quantum processes. Here, we theoretically demonstrate strongly correlated photon-phonon emission enabled by direct tripartite interaction. This interaction facilitates the formation of high-order multiquanta states without more intermediate state transitions, thereby avoiding the suppressed transition rates associated with multiple sequential processes and substantially improving resonant transitions. As a result, high-efficiency strongly correlated even-quanta emission (e.g., two photons and two phonons) can be achieved in the presences of dissipation. Beyond that, we show that introducing two-photon dissipation enables strongly correlated odd-quanta emission (e.g., two photons and one phonon) in the tripartite interaction system by parity-protected suppression of single-photon loss and reconstruction of higher-order multiquanta processes. Our work extends multiquanta emission into the tripartite coupling regime and holds promising potential for applications in hybrid quantum networks.