Two-Wire Waveguide and Interferometer for Cold Atoms

Hinds, E. A.; Vale, Chris; Boshier, M. G.

doi:10.1103/physrevlett.86.1462

Cited by 129 publications

(123 citation statements)

References 18 publications

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“…Our analisys is quite general, and is relevant, for instance, in the study of the splitting and recombination of BEC propagating in atom-chip wave guides [8]. We focus on the role of the collective excitations created during the splitting process as a possible dephasing mechanism.…”

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Double-slit interferometry with a Bose-Einstein condensate

et al. 2005

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A Bose-Einstein "double-slit" interferometer has been recently realized experimentally by Y. Shin et. al., Phys. Rev. Lett. 92 50405 (2004). We analyze the interferometric steps by solving numerically the time-dependent Gross-Pitaevski equation in three-dimensional space. We focus on the adiabaticity time scales of the problem and on the creation of spurious collective excitations as a possible source of the strong dephasing observed experimentally. The role of quantum fluctuations is discussed. PACS numbers:Introduction. Several current efforts in the field of dilute Bose-Einstein condensates (BEC) are focusing on the creation of new technological devices, including quantum computers [1] and ultrasensitive interferometers [2] to detect and measure weak forces. Atom wave interferometry already provides unprecedented sensitivities to detect rotations, accelerations, and gravity gradients [3]. Performances can be further improved with interferometers based on BEC, which are the highest brilliant coherent sources of matter waves and which allow for larger separations between different interferometric paths.Interference between two spatially separated condensates was first demonstrated in [5], and theoretically analyzed in [7]. A BEC trapped in a harmonic magnetic trap was split in two symmetric halves by a laser knife. After releasing the external fields, the interference pattern of the overlapping condensates was observed with destructive imaging. The measured relative phase, however, was not reproducible from shot to shot but was randomly distributed due to the presence of a large noise in the relative positions of the laser and the magnetic trap and of parasite currents when switching off the magnetic fields. Reproducible interference patterns were eventually observed by trapping a condensate in deep optical periodic potentials [6]. Neighboring wells of optical lattices, however, are separated only by a fraction of a micron and cannot be individually addressed, limiting their applications in technological devices.Recently, a stable double-well trap has been created in [4]. A single collimated laser beam was split with an acoustic-optical modulator, and finally focused by a lens. A single, cigar-shaped condensate was trapped in a double-well having a barrier much smaller than the BEC chemical potential, see Fig. (1a). The condensate was then split along the axial direction by linearly increasing, in a ramping time t ramp , both the distance between the two wells and the height of the interwell barrier, see Fig. (1b). The final distance between the two condensates was ∼ 12 µm, allowing for individual addressing and manipulation. After holding the two condensates in the respective traps for a time t hold , the confining field was turned off. The interference pattern of the two overlapping condensates was measured by destructive tech-

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confidence: 99%

Double-slit interferometry with a Bose-Einstein condensate

et al. 2005

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“…03.65.Yz, The decoherence of atomic de Broglie waves is a key issue for applications in atom interferometry and quantum information processing. It is particularly relevant for integrated atom optics based on miniaturized hybrid electromagnetic surface traps [1,2] because the atoms couple to a macroscopic, 'hot' substrate nearby. Loss processes due to spin flips driven by thermal magnetic near fields have very recently been observed in the laboratory [3], in agreement with predictions made by one of us [4].…”

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Decoherence of Bose-Einstein condensates in microtraps

Henkel

Gardiner

2004

Phys. Rev. A

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We discuss the impact of thermally excited near fields on the coherent expansion of a condensate in a miniaturized electromagnetic trap. Monte Carlo simulations are compared with a kinetic two-component theory and indicate that atom interactions can slow down decoherence. This is explained by a simple theory in terms of the condensate dynamic structure factor. 03.65.Yz, The decoherence of atomic de Broglie waves is a key issue for applications in atom interferometry and quantum information processing. It is particularly relevant for integrated atom optics based on miniaturized hybrid electromagnetic surface traps [1,2] because the atoms couple to a macroscopic, 'hot' substrate nearby. Loss processes due to spin flips driven by thermal magnetic near fields have very recently been observed in the laboratory [3], in agreement with predictions made by one of us [4]. In this paper, we discuss a simple decoherence scenario for Bose-Einstein condensed atomic matter waves in a quasi-one-dimensional microtrap. This setup provides a realization of the standard model of environment-induced decoherence [5] featuring two attractive advantages: (i) the coupling to the environment can be microscopically modelled in terms of the magnetic dipole interaction; (ii) due to atomic interactions, the matter wave equation becomes nonlinear and novel features are expected. We compare Monte Carlo simulations for the condensate order parameter to a kinetic theory for the matter wave coherence function and show that already for moderate interaction parameters, a Bose-Einstein condensate is more robust with respect to a fluctuating environment.We consider an elongated trap similar to those formed above current carrying wires [1]. In the confinement dominated regime, the matter waves can be described in a onedimensional mean field approximation [6] (units withh = m = 1),where the interaction parameter g = 2Ω r a/(1 − 1.46a/a r ) depends on the three-dimensional scattering length a, the radial confinement frequency Ω r and ground state size a r [7]. The density |ψ(x, t)| 2 is normalized to the total number of particles N . The potential V (x, t) determines the dynamics in the axial direction. We assume that for t < 0, the atoms are confined in a harmonic trap with frequency Ω and occupy all the zero-temperature condensate mode φ 0 (x) [8].For t ≥ 0, the axial confinement is switched off, the atoms expand, and we take into account their interaction with magnetic field fluctuations by letting V (x, t) be a random potential. Note that the radial confinement is kept constant. Eq. (1) thus describes the interplay between matter wave interactions and time-dependent noise in an essentially one-dimensional geometry. In contrast to previous work in the field of nonlinear random waves [9, 10], our initial condition does not correspond to a self-contained soliton because we assume repulsive interactions g > 0. Current experiments in wire traps have been hampered by the presence of a static field modulation that leads to the fragmentation of the expandi...

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“…As in other interferometers, a longer duration of stage II leads to a larger accumulated phase (i.e., a larger arm length). However, unlike the situation in most free-atom schemes and the guidedatom scheme proposed in [8], in our scheme the atom does not move nor does its wave function spread during this stage: the propagation along the traditional interferometer path is replaced by the evolution in a constant potential (stage II), which leaves the position and the physical size of the wave function unchanged. This interferometer is thus particularly well suited to measure local fields and interactions, which presents an advantage over experiments with propagating atoms 1 .…”

Section: Introductionmentioning

confidence: 99%

“…One promising application of such a system would be an integrated atom interferometer on a chip [8]. The small size and monolithic construction of such a device suggests its suitability for "real-word" applications.…”

Section: Introductionmentioning

confidence: 99%

Trapped-atom interferometer in a magnetic microtrap

et al. 2001

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We propose a configuration of a magnetic microtrap which can be used as an interferometer for three-dimensionally trapped atoms. The interferometer is realized via a dynamic splitting potential that transforms from a single well into two separate wells and back. The ports of the interferometer are neighboring vibrational states in the single well potential. We present a one-dimensional model of this interferometer and compute the probability of unwanted vibrational excitations for a realistic magnetic potential. We optimize the speed of the splitting process in order suppress these excitations and conclude that such interferometer device should be feasible with currently available microtrap technique. 03.75.-b, 03.65.-w, 39.20.+q, 39.25.+k, 39.90.+d

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Two-Wire Waveguide and Interferometer for Cold Atoms

Cited by 129 publications

References 18 publications

Double-slit interferometry with a Bose-Einstein condensate

Double-slit interferometry with a Bose-Einstein condensate

Decoherence of Bose-Einstein condensates in microtraps

Trapped-atom interferometer in a magnetic microtrap

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