We propose an efficient scheme to enhance the generation of optical second-order sidebands (OSSs) in an atom-assisted optomechanical system. The cavity field is coupled with a strong driving field and a weak probe field, and a control field is applied to the atom. We use the steady-state method to analyze the nonlinear interaction in the system, which is different from the traditional linear analysis method. The existence of an auxiliary three-level atom driven by the control field significantly enhances the generation of an OSS. It is found that the efficiency of the OSS can be effectively modulated by adjusting the Rabi frequency of the control field, optomechanical cooperativity and atomic coupling strength. Our scheme provides a promising solution for controlling light propagation and has potential application in quantum optical devices and quantum information networks.
Cavity optomechanics, as a cross-discipline between nanophotonics and quantum mechanics, provides a unique platform for investigating optomechanical coupling between photons in microcavities and phonons from mechanical modes. It has a wide range of potential applications in quantum physics, and now it has become a hot topic. A theoretical scheme to enhance the sum sideband generation (SSG) via a two-level atom ensemble is proposed. The effect of the atomic ensemble’s detuning frequency on the efficiency of the SSG is considered by introducing a two-level atom medium. The results indicate that the efficiency of the generating sideband can be significantly enhanced under either red or blue detuning of the atoms, with greater dependence and more pronounced enhancement under the red detuning. In addition, we also consider the effect of pump power, which can effectively enhance the intensity of the output signal by selecting the appropriate pump power. More interestingly, the sensitivity of SSG to atomic detuning also indicates that the precise control of the atomic detuning frequency can achieve the fine-tuning of the SSG process. Furthermore, the cavity-atom coupling strength and atom decay rate are discussed for the transmission characteristics of the sum sideband signals. It is found that the efficiency of SSG can be effectively adjusted by the cavity-atom coupling strength and atom decay rate. The results show that the efficiency of SSG can be significantly improved by optimizing system parameters. The method of enhancing SSG may have potential application prospects in measuring high-precision weak forces and on-chip manipulation of light propagation.
Realizing highly sensitive charge sensors is of fundamental importance in physics, and may find applications in metrology, electronic tunnel imaging, and engineering technology. With the development of nanophotonics, cavity optomechanics with Coulomb interaction provides a powerful platform to explore new options for the precision measurement of charges. In this work, a method of realizing a highly sensitive charge sensor based on atom-assisted high-order sideband generation in a hybrid optomechanical system is proposed. The advantage of this scheme is that the sideband cutoff order and the charge number satisfy a monotonically increasing relationship, which is more sensitive than the atom-free case discussed previously. Calculations show that the sensitivity of the charge sensor in our scheme is improved by about 25 times. In particular, our proposed charge sensor can operate in low power conditions and extremely weak charge measurement environments. Furthermore, phase-dependent effects between the sideband generation and Coulomb interaction are also discussed in detail. Beyond their fundamental scientific significance, our work is an important step toward measuring individual charge.
Second-order sideband generation (SSG) is investigated in an optomechanical system with atom-cavity-resonator coupling. We focus mainly on the effect of the atomic ensemble trapped in the cavity on the SSG. The numerical results show that the second-order sideband is induced not only for the blue probe-pump detuning resonant case but also for the red one while coupling the atoms with the cavity. Moreover, it is found that the efficiency of the SSG can be significantly enhanced while increasing the atom-cavity coupling strength. More interestingly, the SSG is also sensitive to the atom-pump detuning. It is demonstrated that when optimizing this detuning and the atom-cavity coupling strength together, a robust second-order sideband can be induced and the efficiency of the SSG even surpasses the one of the first-order sideband generation. In addition, the efficiency of the SSG can also be tuned effectively by the decay rate of the atom.
It is quite important to enhance and control the optomechanically induced high-order sideband generation to achieve low-power optical comb and high-sensitivity sensing with an integrable structure. Here we present and analyze a proposal for enhancement and manipulation of optical nonlinearity and high-order sideband generation in a hybrid atom-cavity optomechanical system that is coherently driven by a bichromatic input field consisting of a control field and a probe field and that works beyond the perturbative regime. Our numerical analysis with experimentally achievable parameters confirms that robust high-order sideband generation and typical spectral structures with nonperturbative features can be created even under weak driven fields. The dependence of the high-order sideband generation on the atomic parameters are also discussed in detail, including the decay rate of the atoms and the coupling parameter between the atoms and the cavity field. We show that the cutoff order as well as the amplitude of the higher-order sidebands can be well tuned by the atomic coupling strength and the atomic decay rate. The proposed mechanism of enhancing optical nonlinearity is quite general and can be adopted to optomechanical systems with different types of cavity.
We propose and analyze an effective scheme to enhance the optical higher-order sideband generation in a three-cavity array with local parity-time (
PT) symmetry. In this three-cavity configuration, a single cavity containing a quantum dot (QD) is coupled to an assisted
PT-symmetric combination of two cavities. Beyond the weak-excitation approximation, we derive the analytic formulas used to determine the nonlinear coefficient of the optical second-order sideband (OSS) by employing the perturbation technique. Using experimentally achievable parameters, we identify the conditions under which the assisted
PT-symmetric double-cavity system allows us to modify the transmission of the probe field and improve the efficiency of OSS generation beyond what is achievable in a loss-only QD-cavity system. We examine the influence of the
PT phase transition from unbroken- to broken-
PT regimes on the OSS generation. It is found that the efficiency of optical second-order sideband generation can be significantly enhanced when the assisted double-cavity system is in
PT-symmetric phase, extremely in the vicinity of the transition point. The present results illustrate the potential to utilize
PT-symmetric physical systems for enhancing optical higher-order sidebands and controlling optical frequency combs, as well as to guide the design of experimental implementation.