12 research outputs found
Propagation, breathing and transition of matter-wave packet trains
We find a set of new exact solutions of a quantum harmonic oscillator, which
describes some wave-packet trains with average energy being proportional to
both the quantum level and classical energy of the oscillator. Center of the
wave-packet trains may oscillate like a classical harmonic oscillator of
frequency . Width and highness of the trains may change simultaneously
with frequency as an array of breathers. Under some perturbations
the wave-packet trains could transit between the states of different quantum
numbers. We demonstrate analytically and numerically that the wave-packet
trains can be strictly fitted to the matter-wave soliton trains observed by
Strecher et al. and reported in Nature 417, 150(2002). When the wave-packets
breathe with greater amplitudes, they show periodic collapse and revival of the
matter-wave.Comment: 15 pages, 7 figure
Stabilities of one-dimensional stationary states of Bose-Einstein condensates
We explore the dynamical stabilities of a quasi-one dimensional (1D)
Bose-Einstein condensate (BEC) consisting of fixed atoms with
time-independent external potential. For the stationary states with zero flow
density the general solution of the perturbed time evolution equation is
constructed, and the stability criterions concerning the initial conditions and
system parameters are established. Taking the lattice potential case as an
example, the stability and instability regions on the parameter space are
found. The results suggest a method for selecting experimental parameters and
adjusting initial conditions to suppress the instabilities.Comment: 12 page
Optical operation of ultracold atomic quasi-clusters
We report several exact solutions of a two-dimensional (2D)
Gross-Pitaevskii equation with an optical lattice potential, which
describe the motion of an array of ultracold atomic quasi-clusters
in a Bose-Einstein condensate. The velocity of the atomic
quasi-clusters can be controlled by adjusting the optical
potential strength so that one can stop or drive them by the
optical brake. The atomic quasi-clusters form a superfluid for the
propagation state or a critical insulator for the non-propagation
one, and the brake and drive are associated with the quantum phase
transitions between the insulator and superfluid.
Other topics in quantum fluids and solids; liquid and solid
helium