Dynamical Properties of Two Coupled Dissipative QED Cavities Driven by Coherent Fields

When two identical QED cavities driven by the coherent fields are located in a uniform environment, in addition to dissipation, there appears an indirect coupling between the two cavities induced by the background fields. We investigate the effects of the coherent fields, the dissipation as well as the incoherent coupling on the following dynamical properties of the system： photon transfer, reversible decoherence, and quantum state transfer, etc. We find that the photons in the cavities do not leak completely into the environment due to the collective coupling between the cavities and the enviroment, and the photons are transferred irreversibly from the cavity with more photons to the cavity with less ones due to the incoherent coupling so that they are equally distributed among the two cavities. The coherent field pumping on the two cavities increases the mean photons, complements the revived magnitude of the reversible decoherence, but hinders the quantum state transfer between the two cavities. The above phenomena may find applications in quantum communication and other basic fields.

Differential Representations of SO(4) Dynamical Group

In this paper we present systematic differential representations for the dynamical group SO(4).Theserepresentations include the left and the right differential representations and the left and the right adjoint differentialrepresentations in both the group parameter space and its coset spaces.They are the generalization of the differentialrepresentations of the SO(3) rotation group in the Euler angles.These representations may find their applications in thestudy of the physical systems with SO(4) dynamical symmetry.

Local Control of Two-Photon Absorption in a Six-Level Atomic System by Using a Coherent Perturbation Field

If a coherent perturbation field is used to couple the excited level of the coupling transition in the five-level K-type atom with another higher excited level, the two-photon electromagnetically induced transparency can be locally modulated by altering the parameters of the additional perturbation field. With different detunings of the coherent perturbation field, the absorption peak or transparency window with sharp and high-contrast speetrM feature can be generated in the two-photon absorption spectrum. The physical interpretation of these phenomena is given in terms of the dressed states.

Supersymmetric Quantum Mechanics and SUSY Dependent SU(2) Symmetry for a Spin-1/2 Charged Particle in a Magnetic Field

We find that in a supersymmetric quantum mechanics （SUSY QM） system, in addition to supersymmetric algebra, an associated SU（2） algebra can be obtained by using semiunitary （SUT） operator and projection operator, and the relevant constants of motion can be constructed. Two typical quantum systems are investigated as examples to demonstrate the above finding. The first example is the quantum system of a nonrelativistic charged particle moving in x-y plane and coupled to a magnetic field along z-axis. The second example is provided with the Dirac particle in a magnetic field. Similarly there exists an SUτ（2） SUσ（2） symmetry in the context of the relativistic Pauli Hamilt onian squared. We show that there exists also an SU（2） symmetry associated with the supersvmmetrv of the Dirac particle.

VIC Effect and Phase-Dependent Optical Properties of Five-Level K-Type Atoms Interacting with Coherent Laser Fields

Due to interaction with the vacuum of the radiation field,a K-type atomic system with near-degenerateexcited and ground levels,which is driven by two strong coherent fields and two weak probe fields,has additional coherenceterms—the vacuum-induced coherence (VIC) terms.In this paper,we find that,if the interference is optimized,thetwo-photon absorption properties of this atom system can be significantly modified and electromagnetically-inducedtransparency (EIT) is dependent on this interference.Furthermore,we find that in all the cases the coherence can suppressor enhance the partial two-photon transparency,while the complete transparency window is still strictly preserved,whichmeans that it cannot be affected by the VIC.Another important result is the finding of the crucial role played by therelative phase between the probe and coupling fields:the relative height of absorption peaks can be modulated by therelative phase.The physical interpretation of the phenomena has been given.

Exact Solution to Landau System with Time-Dependent Electromagnetic Fields

Algebraic dynamics is applied to treat Landau system.We consider the case with the vector potential A=B(g)(-y,0,0)and the scalar potentialφ=-E(t)y+k(t)y^(2),and find that the system has the dynamical algebra su(1,1)㊉h⑶.With a gauge transformation the exact solutions of the system are found,of which the quantum motion in y-direction represents a harmonic oscillator with a moving origin and a varying amplitude of width,the paramertes of the gauge transformation are related to the amplitude,the velocity potential and the expectations of y and py,respectively.The energy of the system,the fluctuations of dynamical variables,the transition amplitudes between different states,and the Berry phase are calculated.

A Unified Algebraic Dynamical Solution to General Two-Photon Algebra Systems

We use squeezing and displacement operators and apply algebraic dynamics to develop a unified solution of general time-dependent two-photon algebra systems. A set of orthogonal-and-normalized solutions are derived with the ground state being the conventional squeezed state. Landau system is given as an example.

Fano Resonance and Persistent Currents in a Mesoscopic Open Ring with a Flux Loop in Side-Branch

Persistent circulating currents in a mesoscopic open ring with side-branch structures are derived by transfer matrix method in the framework of quantum waveguide theory on networks.The behavior of transmission probability may show the Fano resonance in the presence of geometric scattering of side-branch structures.It is shown that persistent circulating currents in the main loop with equal length of both arms in the absence of magnetic Aux occur near the Fermi wave vectors where the Fano resonance appears.The numerical results show that a larger persistent current is associated with a stronger Fano resonance.The persistent circulating currents can be controlled by the Aux of side-branch structure.

Light Flavor Vector and Pseudo Vector Mesons from a Light-Cone QCD Inspired Effective Hamiltonian Model with SU（3） Flavor Mixing Interactions

Based on the light-cone effective Hamiltonian with confining potential and SU （3） flavor mixing interactions, the flavor mixing mesons on the u, d, and s quark sectors are investigated. The mass eigen equations of the flavor mixing vector and pseudo vector mesons are solved. The calculated masses are in good agreement with the experimental data.