No Arabic abstract
Realization of strong optomechanical coupling in the single-photon level is crucial to study quantum nonlinear effects and manipulate macroscopic object. Here, we propose an alternative method to towards this goal in a hybrid ensemble-optomechanical system. The sizable membrane-ensemble (ME) coupling mediated by the auxiliary mode of the cavity gives rise to polaritons with lower and higher frequencies. By tuning the ME coupling ($lambda_{rm en}$) approaching the critical coupling value ($lambda_c$), the eigen-energy of the low-frequency polariton gives rise to critical behavior (i.e., quantum phase transition) when the ensemble is within or beyond the low-excitation approximations. Using this critical behavior, the single-photon optomechanical coupling between the cavity and the low-frequency polariton can be greatly enhanced by almost three orders of magnitude with feasible parameters, while the coupling between the high-frequency polariton and the cavity is fully decouped. Our proposal provides a novel way to investigating Kerr effect and blockade in single-photon optomechanical systems.
The possible disruption of a microtubule during mitosis can control the duplication of a cancer cell. Cancer detection and treatment may be possible based on the detection and control of microtubule mechanical oscillations in cells through external fields (e.g. electromagnetic or ultrasound). However, little is known about the dynamic (high-frequency) mechanical properties of microtubules. Here we propose to control the vibrations of a doubly clamped microtubule by tip electrodes and to detect its motion via the optomechanical coupling between the vibrational modes of the microtubule and an optical cavity. In the presence of a red-detuned strong pump laser, this coupling leads to optomechanical induced transparency of an optical probe field, which can be detected with state-of the art technology. The center frequency and linewidth of the transparency peak give the resonance frequency and damping rate of the microtubule respectively, while the height of the peak reveals information about the microtubule-cavity field coupling. Our method should yield new knowledge about the physical properties of microtubules, which will enhance our capability to design physical cancer treatment protocols as alternatives to chemotherapeutic drugs.
We propose to manipulate the statistic properties of the photons transport nonreciprocally via quadratic optomechanical coupling. We present a scheme to generate quadratic optomechanical interactions in the normal optical modes of a whispering-gallery-mode (WGM) optomechanical system by eliminating the linear optomechanical couplings via anticrossing of different modes. By optically pumping the WGM optomechanical system in one direction, the effective quadratic optomechanical coupling in that direction will be enhanced significantly, and nonreciprocal photon blockade will be observed consequently. Our proposal has potential applications for the on-chip nonreciprocal single-photon devices.
The optical bistability have been studied theoretically in a multi-mode optomechanical system with two mechanical oscillators independently coupled to two cavities in addition to direct tunnel coupling between cavities. It is proved that the bistable behavior of mean intracavity photon number in the right cavity can be tuned by adjusting the strength of the pump laser beam driving the left cavity. And the mean intracavity photon number is relatively larger in the red sideband regime than that in the blue sideband regime. Moreover, we have shown that the double optical bistability of intracavity photon in the right cavity and the two steady-state positions of mechanical resonators can be observed when the control field power is increased to a critical value. Besides, the critical values for observing bistability and double bistability can be tuned by adjusting the coupling coefficient between two cavities and the coupling rates between cavities mode and mechanical mode.
Routing of photon play a key role in optical communication networks and quantum networks. Although the quantum routing of signals has been investigated in various systems both in theory and experiment, the general form of quantum routing with multi-output terminals still needs to be explored. Here, we propose an experimentally accessible tunable single-photon multi-channel routing scheme using a optomechanics cavity coulomb coupling to a nanomechanical resonator. The router can extract a single-photon from the coherent input signal directly modulate into three different output channels. More important, the two output signal frequencies can be selected by adjusting Coulomb coupling strength. We also demonstrate the vacuum and thermal noise will be insignificant for the optical performance of the single-photon router at temperature of the order of 20 mK. Our proposal may have paved a new avenue towards multi-channel router and quantum network.
Quantum control of a system requires the manipulation of quantum states faster than any decoherence rate. For mesoscopic systems, this has so far only been reached by few cryogenic systems. An important milestone towards quantum control is the so-called strong coupling regime, which in cavity optomechanics corresponds to an optomechanical coupling strength larger than cavity decay rate and mechanical damping. Here, we demonstrate the strong coupling regime at room temperature between a levitated silica particle and a high finesse optical cavity. Normal mode splitting is achieved by employing coherent scattering, instead of directly driving the cavity. The coupling strength achieved here approaches three times the cavity linewidth, crossing deep into the strong coupling regime. Entering the strong coupling regime is an essential step towards quantum control with mesoscopic objects at room temperature.