Search

We propose a scheme that can generate tunable magnomechanically induced amplification in a double-cavity parity-time-(PT -) symmetric-like magnomechanical system under a strong control and weak probe field. The system consists of a ferromagnetic-material yttrium iron garnet (YIG) sphere placed in a passive microwave cavity which is connected with another active cavity. We reveal that ideally induced amplification of the microwave probe signal may reach the maximum value 1000000 when cavity-cavity, cavity-magnon and magnomechanical coupling strengths are nonzero simultaneously. The phenomenon might have potential applications in the field of quantum information processing and quantum optical devices. Besides, we also find the phenomena of slow-light propagation. In this case, group speed delay of the light can achieve 0.000035s, which can enhance some nonlinear effect. Moreover, due to the relatively flat dispersion curve, the proposal may be applied to sensitive optical switches, which plays an important role in storing photons and quantum optical chips., Comment: 6 pages,6 figures

Sensitive signal detection and processing in classical world, especially in quantum regime, require nonreciprocal manipulation. In this paper we show how to achieve nonreciprocal quantum synchronization for two magnon modes in a two-sublattice antiferromagnet with strong isolation.The antiferromagnet is trapped in a cavity with two posts so that the two magnon modes not only couple to each other through a parametric-type interaction, but also interact with a same cavity respectively in a beam splitter-type and parametric-type ways. Under the condition of system's stability, we show that nonreciprocal quantum synchronization between two magnon modes is mainly dependent on resonance frequency of the cavity caused by direction of input currents. In addition,quantum synchronization is enhanced by the increase of interaction strength between two Bogoliubov modes and cavity mode. Moreover, numerical simulation results with parameters commonly used in current experiments show that the present scheme may be feasible., Comment: 8 pages, 5 figures. arXiv admin note: text overlap with arXiv:1408.2905 by other authors

Quantum entanglement, a key element for quantum information is generated with a cavity-magnomechanical system. It comprises of two microwave cavities, a magnon mode and a vibrational mode, and the last two elements come from a YIG sphere trapped in the second cavity. The two microwave cavities are connected by a superconducting transmission line, resulting in a linear coupling between them. The magnon mode is driven by a strong microwave field and coupled to cavity photons via magnetic dipole interaction, and at the same time interacts with phonons via magnetostrictive interaction. By breaking symmetry of the configuration, we realize nonreciprocal photon transmission and one-way bipartite quantum entanglement. By using current experimental parameters for numerical simulation, it is hoped that our results may reveal a new strategy to built quantum resources for the realization of noise-tolerant quantum processors, chiral networks, and so on., Comment: 8 pages, 5 figures

We present a scheme to implement a steady lightwave-photon-and-magnon entanglement in a hybrid photon-magnon system by adiabatically eliminating the auxiliary microwave cavity and effectively laser cooling a delocalized Bogoliubov mode. The system consists of magnons, lightwave and microwave photons, and phonons. The magnons are embodied by a collective motion of a large number of spins in a macroscopic ferrimagnet. To achieve an entangling interaction between magnons and lightwave photons, we drive optical cavity and magnon at the red and blue sideband associated with the mechanical resonator. In particular, optimizing the relative ratio of effect couplings, rather than simply increasing their magnitudes, is essential for achieving strong entanglement. Unlike typical dissipative entanglement schemes, our results cannot be described by treating the effects of the entangling reservoir via a Linblad master equation., Comment: There are some great mistakes and problems on the contents, languages and references

In this paper, correlation dynamics for two two-level atoms distributed in two isolated thermal cavities are studied, where the atomic state is initially prepared in a maximum entangled zero-and-two-excitation superposition state. We use two nonclasscal measures including geometric quantum discord via Schatten one norm and concurrence to analyze correlation dynamics for the two atoms when the two cavities have the same or different mean photon numbers. We find though correlation dynamics for these two measures have different features, they have the same characteristics in some particular time when the nonclassical correlation is robust against thermal photon numbers. This result may be important in quantum information processing and quantum computation.

A theoretical scheme is presented for the adiabatic generation of N-quNit singlet states with $N\geqslant3$, which may be more feasible than previous ones in a cavity. In this proposal, the system may be robust both parameter fluctuations and dissipation along a dark state. In addition, quantum information is only stored in atomic ground states and there is no energy exchanged between atoms and photons in a cavity so as to reduce the influence of atomic spontaneous emission and cavity decays., Comment: 7 pages,5 figures

A proposal for the generation of singlet states of three $\Lambda$-type Rydberg atoms is presented. The singlet state is prepared through the combination of a Rydberg state and an EPR pair, and the scheme relies on the Rydberg blockade effect which prevents the simultaneous excitation of the two atoms to a Rydberg state. In addition, some frequency detuning between lasers and atomic transitions is set to eliminate the degenerate of the two ground states. And finally, a series of numerical simulations are made to show the feasibility of the scheme., Comment: 8 pages,5 figures