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Engineering topics

Wenhua, Hai

Publications and source records attributed to Wenhua, Hai.

7 records

All sources NASA NTRS DOE OSTI

DOE OSTI2012

Different routes from a matter wavepacket to spatiotemporal chaos

We investigate the dynamics of a quasi-one-dimensional Bose-Einstein condensate confined in a double-well potential with spatiotemporally modulated interaction. A variety of phenomena is identified in different frequency regimes, including the self-compression, splitting, breathing-like, and near-fidelity of the matter wavepacket, which are associated with different routes for the onset of spatiotemporal chaos. The results also reveal that chaos can retain space-inversion symmetry of the system.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2011

Incoherent control in a non-Hermitian Bose-Hubbard dimer

We investigate the combined effect of the particle-particle interaction and non-Hermiticity on the quantum states and energy spectra for a non-Hermitian Bose-Hubbard dimer with complex coupling constant. It is analytically and numerically found that a real energy appears uniquely when a balance between the interaction strength and non-Hermiticity is established. The corresponding quantum state is a stationary state which does not decay in time evolution. The result provides a route for enhancing survival probability of an open many-body system and for incoherently controlling quantum transition between the stationary states by modulating the interaction strength to fit the different balance conditions.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2011

Quantum tunneling switch in a planar four-well system

We investigate the tunneling dynamics of a single atom in a planar four-well potential driven by a high-frequency ac field. The quasienergy spectrum exhibits anticrossing and crossing, which are related to selective coherent destruction of tunneling (CDT) with several selectable directions. By using the CDTs of different directions, the switchlike effect is shown for the six tunneling pathways among the four wells. Applying the present results, we suggest a scheme for designing a single-atom quantum motor with the driving field as a quantum starter.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2011

Coherent control of atomic tunneling in a driven triple well

Coherent control of quantum tunneling is investigated for a single atom held in a driven triple-well potential without tight-binding approximation. In the high-frequency regime within or without multiphoton resonance, we find the analytical solutions and their numerical correspondences, including the special Floquet states of invariant populations and the non-Floquet states of slowly varying populations. The Floquet quasienergy spectrum exhibits anticrossings and crossings for different values of the driving parameters, which are associated with different tunneling properties described by the non-Floquet states. Applying the presented results, we suggest a scheme for transporting a single atom between nonadjacent wells or between adjacent wells.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2010

Controlling transport and entanglement of two particles in a bipartite lattice

We consider two Bose particles held in a bipartite lattice with two different separations fitting the nearest-neighbor tight-binding approximation. Applying a strong driving field of high frequency and a large interaction intensity, we analytically construct entangled Floquet states and slowly varying Rabi-oscillation states of the system. Under the interaction-independent and interaction-dependent conditions of the selective coherent destruction of tunneling, we propose a scheme for manipulating separated and co-site transports of the two particles in the same or opposite directions. The results could be useful for transporting quantum information carried by a few particles in a bipartite superlattice.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2010

Analytical results for a monochromatically driven two-level system

We show that the frequently encountered physical model of a monochromatically driven two-level system is exactly solvable. We present an analytical exact solution to this driven system in terms of two known special functions. Our analytical solution is valid for all parameter regimes and may find applications in current solid-state experiments.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2010

Photon-assisted tunneling of a driven two-mode Bose-Einstein condensate

We investigate the photon-assisted tunneling of a Bose-Einstein condensate in a periodically driven double-well potential. It is shown that the energy levels become nonequidistant due to the presence of the interatomic interaction, thereby leading to the occurrences of the fractional photon resonances. Depending on whether the resonance frequency shifts with the interatomic interaction, two distinct types of resonances are identified: nonshifting resonances and shifting resonances. In particular, certain nonshifting fractional resonances show an odd-even sensitivity to the atom number.

74 ATOMIC AND MOLECULAR PHYSICS↗