Physical Review A

Stability and dynamical property for two-species ultracold atoms in double wells

Xiaoqiang Xu, Li-Hua Lü, You‐Quan Li

Published Oct 14, 2008• 46 citations

Abstract

We study undistinguishable two-species Bose-Einstein condensates (BECs) trapped in double wells. In the mean-field approximation we map the quantum system into a classical model and investigate the existence and stability of the fixed point solutions. By appropriately varying the amplitude of the high-frequency periodic modulation on the energy bias between the two wells, we tune the tunneling strength in the adiabatic Rosen-Zener type effectively. Starting from two typical initial states, we study the evolution of the system and find that the interspecies interaction can produce totally distinct results, which is expected to provide a route to manipulate the BEC distribution.

DOI: 10.1103/physreva.78.043609

Related papers

The role of inter-well tunnelling strength on coherence dynamics of two-species Bose–Einstein condensates

Li-Hua Lü, Xiaoqiang Xu, You‐Quan Li

Coherence dynamics of two-species Bose–Einstein condensates in double wells is investigated in the mean-field approximation. We show that the system can exhibit decoherence phenomena even without the condensate–environment coupling and the variation tendency of the degree of coherence depends not only on the parameters of the system but also the initial states. We also investigate the time evolution of the degree of coherence for a Rosen–Zener form of tunnelling strength, and propose a method to get a condensate system with a certain degree of coherence through a time-dependent tunnelling strength.

arXiv:1102.5622Journal of Physics B Atomic Molecular and Optical PhysicsJun 23, 20114 citations

Time-dependent self-trapping of Bose-Einstein condensates in a double-well potential

B. Cui, L. C. Wang, X. X. Yi

Based on the mean-field approximation and a phase-space analysis, we discuss the dynamics of Bose-Einstein condensates (BECs) in a double-well potential. The condensates are found to be trapped in the time-dependent eigenstates of the effective Hamiltonian; we refer to this effect as time-dependent self-trapping of BECs. By comparison of this self-trapping with the adiabatic evolution, we find that adiabatic evolution beyond the traditional adiabatic condition can be achieved in BECs. Furthermore, the population imbalance of the BECs in the wells can be controlled by manipulating the atom-atom couplings and the driving field. The fixed points for the system are also calculated and discussed.

arXiv:1009.3666Physical Review ADec 7, 201024 citations

Josephson junction of two-species Bose—Einstein condensates in a high-finesse optical cavity

Bin Wang, Lei Tan, 吕纯海 +1 more

The mean-field dynamics of undistinguishable two-species Bose Josephson junction coupled to a single mode highfinesse optical cavity is investigated. From the Hamiltonian, the phase portrait and the stationary points are given. It is shown that the role of the interspecies interaction equals the intraspecies interaction under suitable conditions. As the interspecies interaction increases, the trapped atoms will start tunneling between the two wells unnaturally for some special cases.

Chinese Physics BNov 1, 20104 citations

One-BEC-species coherent oscillations with frequency controlled by a second species atom number

L. Morales-Molina, E Arévalo

Abstract Controlling the tunneling of atoms of one species using a different atom species is a fundamental step in the development of a new class of atom quantum devices, where detection, motion control, and other functions over the atoms, can be achieved by exploiting the interaction between two different atomic species. Here, we theoretically study coherent oscillations of a non-self-interacting Bose–Einstein condensate (BEC) species in a triple-well potential controlled by a self-interacting species self-trapped in the central well of the potential. In this system, a blockade, due to the interspecies interaction, prevents atoms of the non-self-interacting species from populating the central well. Thus, for an initial population imbalance between the left- and right-hand wells of the non-self-interacting species, coherent BEC oscillations are induced between these two wells, resembling those of Rabi-like BEC oscillations in a double-well potential. The oscillation period is found to scale linearly with the number of self-trapped atoms as well as with the interspecies interaction strength. This behavior is corroborated by the quantum many-particle and the mean-field models of the system. We show that BEC oscillations can be described by using an effective bosonic Josephson junction with a tunneling amplitude that depends on the number of the self-trapped atoms in the central well. We also consider the effect of the self-trapped atom losses on the coherent oscillations. We show, by using quantum trajectories, that this type of losses leads to a dynamical change in the oscillation period of the non-self-interacting species, which in turn allows the number of self-trapped atoms lost from the system to be estimated.

New Journal of PhysicsDec 7, 20213 citations

Nonlinear dynamics of a spinor Bose-Einstein condensate in a double-well potential

Özgür Esat Müstecaplıoğlu, Mei Zhang, Li You

We examine the nonlinear dynamical behavior of a spinor Bose-Einstein condensate in a double-well potential. Considering a condensate with large number of atoms, such that it can be described using the mean field theory, we separate the spinor dynamics from the spatial dynamics under the single-mode approximation. We limit ourselves to certain initial conditions under which the spatial mode is frozen so that we can focus on the spinor dynamics only. Identifying collective spin variables of our system, we derive the corresponding nonlinear equations of motion for them. Employing standard stability analysis, we find and characterize fixed points of the system. For a wide range of physical parameters such as tunneling strength and non-linear interactions, as well as for various initial preparations of the system, we identify qualitatively different dynamical regimes possible in the system. In particular, complete and incomplete oscillations of spin variables between quantum wells are found. We also show that by bringing some fixed points close to each other in the phase space of the system, it is possible to induce amplitude modulation to those otherwise regular tunneling oscillations.

Laser PhysicsFeb 1, 20060 citations

Interaction-modulated tunneling dynamics of a mixture of Bose-Fermi superfluid

Hong-Ping Xu, Zhen-Zhen He, Zi-Fa Yu +1 more

In this paper, we study the interaction-modulated tunneling dynamics of a Bose-Fermi superfluid mixture, where a Bose-Einstein condensate (BEC) with weak repulsive interaction is confined in a symmetric deep double-well potential and an equally populated two-component Fermi gas in a harmonic potential symmetrically is positioned in the center of the double-well potential. The tunneling between the two wells is modulated by fermions trapped in a harmonic potential. When the temperature is adequately low and the bosonic particle number is adequately large, we can employ the mean-field theory to describe the evolution of the BEC in the double-well potential through the time-dependent Gross-Pitaevskii equation. For the Fermi gas in the harmonic potential trap, we consider the case where the inter-fermion interaction is tuned on the deep Bose-Einstein condensate of the inter-fermion Feshbach resonance, where two fermions of spin-up and spin-down form a two-body bound state. Within the regime, the Fermi gas is well described by a condensate of these fermionic dimers, and hence can be simulated as well by a Gross-Pitaevskii equation of dimers. The inter-species interactions couple the dynamics of the two species, which results in interesting features in the tunneling oscillations. The dynamic equations of the BEC in the double-well potential is described by a two-mode approximation. Coupling it with time-dependent Gross-Pitaevskii equation of the harmonically potential trapped molecular BEC, we numerically investigate the dynamical evolution of the Boson-Fermi hybrid system under different initial conditions. It is found that the interaction among fermions in a harmonic potential leads to strong non-linearity in the oscillations of the bosons in the double-well potential and enriches the tunneling dynamics of the bosons. Especially, it strengthens macroscopic quantum self-trapping. And the macroscopic quantum self-trapping can be expressed in three forms: the phase tends to be negative and monotonically decreases with time, the phase evolves with time, and the phase tends to be positive and increases monotonically with time. This means that it is possible the tunneling dynamics of the BEC in double-well potential is adjustable. Our results can be verified experimentally in a Bose-Fermi superfluid mixture by varying different interaction parameters via Feshbach resonance and confinement-induced resonance.

Acta Physica SinicaJan 1, 20221 citation