Coherent Quantum Tunneling of Bose-Einstein Condensates in Optical Lattices (original) (raw)

Resonant tunneling of Bose–Einstein condensates in optical lattices

New Journal of …, 2008

In this article, we present theoretical as well as experimental results on resonantly enhanced tunneling of Bose-Einstein condensates in optical lattices both in the linear case and for small nonlinearities. Our results demonstrate the usefulness of condensates in optical lattices for simulating Hamiltonians originally used for describing solid state phenomena.

Macroscopic Quantum Tunneling of Solitons in Bose-Einstein Condensates

2011

We study the quantum tunneling dynamics of many-body entangled solitons composed of ultracold bosonic gases in 1D optical lattices. A bright soliton, confined by a potential barrier, is allowed to tunnel out of confinement by reducing the barrier width and for varying strengths of attractive interactions. Simulation of the Bose Hubbard Hamiltonian is performed with time-evolving block decimation. We find the characteristic 1/e1/e1/e time for the escape of the soliton, substantially different from the mean field prediction, and address how many-body effects like quantum fluctuations, entanglement, and nonlocal correlations affect macroscopic quantum tunneling; number fluctuations and second order correlations are suggested as experimental signatures. We find that while the escape time scales exponentially in the interactions, the time at which both the von Neumann entanglement entropy and the slope of number fluctuations is maximized scale only linearly.

Josephson tunneling between weakly interacting Bose-Einstein condensates

Physical Review A, 2001

Based on a tunneling Hamiltonian description, we calculate the Josephson, normal, and interference currents between two Bose-Einstein condensates described by the Bogoliubov theory. The dominant Josephson term is of first order in the tunneling with a critical current density proportional to the ground state pressure. In contrast to superconductors, the normal current remains finite at zero temperature. We discuss the

Superfluid Dynamics of a Bose-Einstein Condensate in a Quantum Optical Lattice

arXiv (Cornell University), 2007

We study the effect of a one dimensional optical lattice in a cavity field with quantum properties on the superfluid dynamics of a Bose-Einstein condensate(BEC). In the cavity the influence of atomic backaction and the external driving pump become important and strongly modify the optical potential. Due to the strong coupling between the condensate wavefunction and the cavity modes, the cavity light field develops a band structure. This study reveals that the pump and the cavity emerges as a new handle to control the superfluid properties of the BEC.

Superfluid properties of a Bose–Einstein condensate in an optical lattice confined in a cavity

Optics Communications, 2008

We study the effect of a one dimensional optical lattice in a cavity field with quantum properties on the superfluid dynamics of a Bose-Einstein condensate(BEC). In the cavity the influence of atomic backaction and the external driving pump become important and modify the optical potential. Due to the coupling between the condensate wavefunction and the cavity modes, the cavity light field develops a band structure. This study reveals that the pump and the cavity emerges as a new handle to control the superfluid properties of the BEC.

Analog of Photon-Assisted Tunneling in a Bose-Einstein Condensate

We study many-body tunneling of a small Bose-Einstein condensate in a periodically modulated, tilted double-well potential. Periodic modulation of the trapping potential leads to an analog of photon-assisted tunneling, with distinct signatures of the interparticle interaction visible in the amount of particles transferred from one well to the other. In particular, under experimentally accessible conditions there exist well-developed half-integer Shapiro-like resonances.

Loss of Superfluidity in Bose-Einstein Condensate in an Optical lattice with Two- and Three-Body Interactions

arXiv (Cornell University), 2007

In a one dimensional shallow optical lattice, in the presence of both cubic and quintic nonlinearity, a superfluid density wave, is identified in Bose-Einstein condensate. Interestingly, it ceases to exist, when only one of these interaction is operative. We predict the loss of superfluidity through a classical dynamical phase transition, where modulational instability leads to the loss of phase coherence. In certain parameter domain, the competition between lattice potential and the interactions, is shown to give rise to a stripe phase, where atoms are confined in finite domains. In pure two-body case, apart from the known superfluid and insulating phases, a density wave insulating phase is found to exist, possessing two frequency modulations commensurate with the lattice potential.

Tunneling of ultracold Bose gases in multiple wells

Physical Review A, 2006

We study the dynamics of an ultracold gas of interacting bosons confined in a one-dimensional potential composed of n wells. We derive an effective N-particle Hamiltonian for this system that describes the tunneling of particles between adjacent wells and that includes the interactions among the particles within the same well. The problem is discussed in the light of current research on optical lattices. We demonstrate that the effective Hamiltonian gives the possibility of studying the transition from an ideal insulator to a real conductor when the parameters that modulate the interaction and the tunneling of the particles are varied. To show this we numerically solve Schrödinger equation for the case of n = 3 wells. We find that for a given number of particles it is possible to establish a weak-and a strong-interaction regime. In the limit of strong interaction the tunneling term can be neglected. One important result in our analysis is that in the weak-interaction regime the system reaches a stationary state as a result of the loss of coherence in the transport of particles through the wells.