We propose a method to entangle two vibrating microsize mirrors （i.e., mechanical oscillators） in a cavity optomechanieal system. In this scheme, we discuss both the resonant and large-detuning conditions, and show ...We propose a method to entangle two vibrating microsize mirrors （i.e., mechanical oscillators） in a cavity optomechanieal system. In this scheme, we discuss both the resonant and large-detuning conditions, and show that the entanglement of two mechanical oscillators can be achieved with the assistance of a two-level atom and cavity-radiation pressure. In the resonant case, the operation time is relatively short, which is desirable to minimize the effects of decoherence. While in the large-detuning case, the cavity is only virtually excited during the interaction. Therefore, the decay of the cavity is effectively suppressed, which makes the efficient decoherence time of the cavity to be greatly prolonged. Thus, we observe that this virtual-photon process of microscopic objects may induce the entanglement of macroscopic objects. Moreover, in both cases, the generation of entanglement is deterministic and no measurements on the atom and the cavity are required. These are experimentally important. Finally, the decoherence effect and the experimental feasibility of the proposal are briefly discussed.展开更多
We investigate the single-photon scattering properties of a driven three-level giant atom chirally coupled to two waveguides simultaneously in both the Markovian and the non-Markovian regimes.It is shown that under th...We investigate the single-photon scattering properties of a driven three-level giant atom chirally coupled to two waveguides simultaneously in both the Markovian and the non-Markovian regimes.It is shown that under the Markovian limit,the chiral photon-atom interactions enable nonreciprocal scattering in a single waveguide and targeted photon routing with a probability of 100%in two waveguides,while the presence of the driving field and the giant atom structure introduce a more tunable parameter to manipulate the single-photon scattering behaviors.We also examine how the non-reciprocity and routing capability are influenced by the imperfect chirality and the atomic dissipation.In the non-Markovian regime,we show that the scattering behaviors are more complicated.The non-Markovicity induced non-reciprocity and photon routing are demonstrated in this paper.We believe that those results have potential applications in quantum network engineering.展开更多
The biomolecular motor kinesin uses chemical energy released from a fuel reaction to generate di- rectional movement and produce mechanical work. The underlying physical mechanism is not fully understood yet. To analy...The biomolecular motor kinesin uses chemical energy released from a fuel reaction to generate di- rectional movement and produce mechanical work. The underlying physical mechanism is not fully understood yet. To analyze the energetics of the motor, we reconceptualize its chemomechanical cy- cle in terms of separate fuel reaction and work production processes and introduce a thermodynamic constraint to optimize the cycle. The model predicts that the load dependences of the motor＇s veloc- ity, stepping ratio, and dwell time are determined by the mechanical parameters of the motor-track system rather than the fuel reaction rate. This behavior is verified using reported experimental data from wild-type and elongated kinesins. The fuel reaction and work production processes indicate that kinesin is driven by switching between two chemical states, probably following a general pattern for molecular motors. The comparison with experimental data indicates that the fuel reaction processes are close to adiabatic, which is important for efficient operation of the motor. The model also suggests that a soft, short neck linker is important for the motor to maintain its load transport velocity.展开更多
In this work, we propose a high-fidelity phonon-mediated entangling gate in a hybrid mechanical system based on two silicon-vacancy color centers in diamond. In order to suppress the influence of the spin decoherence ...In this work, we propose a high-fidelity phonon-mediated entangling gate in a hybrid mechanical system based on two silicon-vacancy color centers in diamond. In order to suppress the influence of the spin decoherence on the entangling gate, we use a continuous dynamical decoupling approach to create new dressed spin states, which are less sensitive to environmental fluctuations and exhibit an extended T_(2)^(*) spin dephasing time. The effective spin-spin Hamiltonian modified by the mechanical driving field and the corresponding master equation are derived in the dispersive regime. We show that in the presence of the mechanical driving field, the effective spin-spin coupling can be highly controlled. By calculating the entangling gate fidelity in the dressed basis, we find that once the mechanical field is turned on, the gate fidelity can be significantly improved. In particular, under an optimized spin-phonon detuning and a stronger Rabi frequency of the mechanical driving field, the two-qubit gate is capable of reaching fidelity exceeding 0.99. Moreover, by employing appropriate driving modulation, we show that a highfidelity full quantum gate can be also realized, in which the initial and final spin states are on a bare basis. Our work provides a promising scheme for realizing high-fidelity quantum information processing.展开更多
基金This work was supported by the National Natural Science Foundation of China under Grant Nos. 11674060, 11404061, and 11705030, the Natural Science Foundation of Fujian Province under Grant No. 2016J01018, and the Fujian Provincial Department of Education under Grant No. JZ160422.
文摘We propose a method to entangle two vibrating microsize mirrors （i.e., mechanical oscillators） in a cavity optomechanieal system. In this scheme, we discuss both the resonant and large-detuning conditions, and show that the entanglement of two mechanical oscillators can be achieved with the assistance of a two-level atom and cavity-radiation pressure. In the resonant case, the operation time is relatively short, which is desirable to minimize the effects of decoherence. While in the large-detuning case, the cavity is only virtually excited during the interaction. Therefore, the decay of the cavity is effectively suppressed, which makes the efficient decoherence time of the cavity to be greatly prolonged. Thus, we observe that this virtual-photon process of microscopic objects may induce the entanglement of macroscopic objects. Moreover, in both cases, the generation of entanglement is deterministic and no measurements on the atom and the cavity are required. These are experimentally important. Finally, the decoherence effect and the experimental feasibility of the proposal are briefly discussed.
文摘We investigate the single-photon scattering properties of a driven three-level giant atom chirally coupled to two waveguides simultaneously in both the Markovian and the non-Markovian regimes.It is shown that under the Markovian limit,the chiral photon-atom interactions enable nonreciprocal scattering in a single waveguide and targeted photon routing with a probability of 100%in two waveguides,while the presence of the driving field and the giant atom structure introduce a more tunable parameter to manipulate the single-photon scattering behaviors.We also examine how the non-reciprocity and routing capability are influenced by the imperfect chirality and the atomic dissipation.In the non-Markovian regime,we show that the scattering behaviors are more complicated.The non-Markovicity induced non-reciprocity and photon routing are demonstrated in this paper.We believe that those results have potential applications in quantum network engineering.
基金This work was supported by the National Natural Science Foundation of China under Crant No. 11774284 （to H. R. Li） and Grant No. 11534008.
文摘The biomolecular motor kinesin uses chemical energy released from a fuel reaction to generate di- rectional movement and produce mechanical work. The underlying physical mechanism is not fully understood yet. To analyze the energetics of the motor, we reconceptualize its chemomechanical cy- cle in terms of separate fuel reaction and work production processes and introduce a thermodynamic constraint to optimize the cycle. The model predicts that the load dependences of the motor＇s veloc- ity, stepping ratio, and dwell time are determined by the mechanical parameters of the motor-track system rather than the fuel reaction rate. This behavior is verified using reported experimental data from wild-type and elongated kinesins. The fuel reaction and work production processes indicate that kinesin is driven by switching between two chemical states, probably following a general pattern for molecular motors. The comparison with experimental data indicates that the fuel reaction processes are close to adiabatic, which is important for efficient operation of the motor. The model also suggests that a soft, short neck linker is important for the motor to maintain its load transport velocity.
基金supported by the Natural Science Foundation of Henan Province (No. 222300420233)。
文摘In this work, we propose a high-fidelity phonon-mediated entangling gate in a hybrid mechanical system based on two silicon-vacancy color centers in diamond. In order to suppress the influence of the spin decoherence on the entangling gate, we use a continuous dynamical decoupling approach to create new dressed spin states, which are less sensitive to environmental fluctuations and exhibit an extended T_(2)^(*) spin dephasing time. The effective spin-spin Hamiltonian modified by the mechanical driving field and the corresponding master equation are derived in the dispersive regime. We show that in the presence of the mechanical driving field, the effective spin-spin coupling can be highly controlled. By calculating the entangling gate fidelity in the dressed basis, we find that once the mechanical field is turned on, the gate fidelity can be significantly improved. In particular, under an optimized spin-phonon detuning and a stronger Rabi frequency of the mechanical driving field, the two-qubit gate is capable of reaching fidelity exceeding 0.99. Moreover, by employing appropriate driving modulation, we show that a highfidelity full quantum gate can be also realized, in which the initial and final spin states are on a bare basis. Our work provides a promising scheme for realizing high-fidelity quantum information processing.
