1,945 research outputs found
Transition to an oscillator for double phase-conjugate mirror
Summary form only given. Some of the novel quantified characteristics for double phase conjugate mirrors are analysed including the effects of the nonlinearity on the critical dynamics (approach to saturation) and on the spatial distribution of the grating (large scale distortion of the beams and conjugation fidelity) and sensitivity to noise (seeding). The approach used also clarifies the question of linear instability and predicts a new transition to an oscillatory regime
Quantum Nondemolition Measurement of Discrete Fock States of a Nanomechanical Resonator
We study theoretically a radio frequency superconducting interference device
integrated with both a nanomechanical resonator and an LC one. By applying
adiabatic and rotating wave approximations, we obtain an effective Hamiltonian
that governs the dynamics of the mechanical and LC resonators. Nonlinear terms
in this Hamiltonian can be exploited for performing a quantum nondemolition
measurement of Fock states of the nanomechanical resonator. We address the
feasibility of experimental implementation and show that the nonlinear coupling
can be made sufficiently strong to allow the detection of discrete mechanical
Fock states
Anderson localization of a Tonks-Girardeau gas in potentials with controlled disorder
We theoretically demonstrate features of Anderson localization in the
Tonks-Girardeau gas confined in one-dimensional (1D) potentials with controlled
disorder. That is, we investigate the evolution of the single particle density
and correlations of a Tonks-Girardeau wave packet in such disordered
potentials. The wave packet is initially trapped, the trap is suddenly turned
off, and after some time the system evolves into a localized steady state due
to Anderson localization. The density tails of the steady state decay
exponentially, while the coherence in these tails increases. The latter
phenomenon corresponds to the same effect found in incoherent optical solitons
The single-particle density matrix and the momentum distribution of dark "solitons" in a Tonks-Girardeau gas
We study the reduced single-particle density matrix (RSPDM), the momentum
distribution, natural orbitals and their occupancies, of dark "soliton" (DS)
states in a Tonks-Girardeau gas. DS states are specially tailored excited
many-body eigenstates, which have a dark solitonic notch in their
single-particle density. The momentum distribution of DS states has a
characteristic shape with two sharp spikes. We find that the two spikes arise
due to the high degree of correlation observed within the RSPDM between the
mirror points ( and ) with respect to the dark notch at ; the
correlations oscillate rather than decay as the points and are being
separated.Comment: 9 pages, 8 figure
Incoherent matter-wave solitons
The dynamics of matter-wave solitons in Bose-Einstein condensates (BEC) is
considerably affected by the presence of a surrounding thermal cloud and by
condensate depletion during its evolution. We analyze these aspects of BEC
soliton dynamics, using time-dependent Hartree-Fock-Bogoliubov (TDHFB) theory.
The condensate is initially prepared within a harmonic trap at finite
temperature, and solitonic behavior is studied by subsequently propagating the
TDHFB equations without confinement. Numerical results demonstrate the collapse
of the BEC via collisional emission of atom pairs into the thermal cloud,
resulting in splitting of the initial density into two solitonic structures
with opposite momentum. Each one of these solitary matter waves is a mixture of
condensed and noncondensed particles, constituting an analog of optical
random-phase solitons.Comment: 4 pages, 2 figures, new TDHFB result
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