161 research outputs found

    Adiabatic Mach-Zehnder interferometry on a quantized Bose-Josephson junction

    Get PDF
    We propose a scheme to achieve Mach-Zehnder interferometry using a quantized Bose-Josephson junction with a negative charging energy. The quantum adiabatic evolution through a dynamical bifurcation is used to accomplish the beam splitting and recombination. The negative charging energy ensures the existence of a path-entangled state which enhances the phase measurement precision to the Heisenberg limit. A feasible detection procedure is also presented. The scheme should be realizable with current technology

    Enhanced Quantum Reflection of Matter-Wave Solitons

    Full text link
    Matter-wave bright solitons are predicted to reflect from a purely attractive potential well although they are macroscopic objects with classical particle-like properties. The non-classical reflection occurs at small velocities and a pronounced switching to almost perfect transmission above a critical velocity is found, caused by nonlinear mean-field interactions. Full numerical results from the nonlinear Schr\"{o}dinger equation are complimented by a two-mode variational calculation to explain the predicted effect, which can be used for velocity filtering of solitons. The experimental realization with laser-induced potentials or two-component Bose-Einstein condensates is suggested.Comment: 7 pages, 3 figures, to be published in Europhys. Let

    Universality and Anomalous Mean-Field Breakdown of Symmetry-Breaking Transitions in A Coupled Two-Component Condensate

    Full text link
    We study both mean-field and full quantum dynamics of symmetry-breaking transitions (SBTs) in a coupled two-component Bose-Einstein condensate. By controlling s-wave scattering lengths and coupling strength, it is possible to stimulate SBTs between normal and spontaneously polarized ground states. In static transitions, the probability maxima of full quantum ground states correspond to the mean-field ground states. In dynamical transitions, due to the vanishing of excitation gaps, the mean-field dynamics shows universal scalings obeying Kibble-Zurek mechanism. Both mean-field and full quantum defect modes appear as damped oscillations, but they appear at different critical points and undergo different oscillation regimes. The anomalous breakdown of mean-field dynamics induced by SBTs depends on the approaching direction.Comment: 4 pages, 3 eps figures, revised and improved versio

    Propagation, breathing and transition of matter-wave packet trains

    Get PDF
    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 ω\omega. Width and highness of the trains may change simultaneously with frequency 2ω2 \omega 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

    Many-body quantum coherence and interaction blockade in Josephson-linked Bose-Einstein condensates

    Full text link
    We study many-body quantum coherence and interaction blockade in two Josephson-linked Bose-Einstein condensates. We introduce universal operators for characterizing many-body coherence without limitations on the system symmetry and total particle number NN. We reproduce the results for both coherence fluctuations and number squeezing in {\em symmetric} systems of large NN, and reveal several peculiar phenomena that may occur in {\em asymmetric} systems and systems of small NN. For asymmetric systems, we show that, due to an interplay between asymmetry and inter-particle interaction, the coherence fluctuations are suppressed dramatically when ∣EC/EJ∣≪1|E_{C}/E_{J}|\ll 1, and both {\it resonant tunneling} and {\it interaction blockade} take place for large values of ∣EC/EJ∣|E_{C}/E_{J}|, where ECE_C and EJE_J are the interaction and tunneling energies, respectively. We emphasize that the resonant tunneling and interaction blockade may allow creating single-atom devices with promising technology applications. We demonstrate that for the systems at finite temperatures the formation of self-trapped states causes an anomalous behavior.Comment: 6 pages, 5 figures, accepted for publication in EPL (Europhysics Letters
    • …
    corecore