Condensate Splitting in an Asymmetric Double Well for Atom Chip Based Sensors

Hall, Budd L.; Whitlock, S.; Anderson, R. A.; Hannaford, Peter; Sidorov, Andrei

doi:10.1103/physrevlett.98.030402

Cited by 89 publications

(74 citation statements)

References 22 publications

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“…[7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. It is a common practice that in order to produce a fragmented BEC in the splitting process, the ground state must be fragmented.…”

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confidence: 99%

Breaking the resilience of a two-dimensional Bose-Einstein condensate to fragmentation

et al. 2014

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A two-dimensional Bose-Einstein condensate (BEC) split by a radial potential barrier is investigated. We determine on an accurate many-body level the system's ground-state phase diagram as well as a time-dependent phase diagram of the splitting process. Whereas the ground state is condensed for a wide range of parameters, the time-dependent splitting process leads to substantial fragmentation. We demonstrate for the first time the dynamical fragmentation of a BEC despite its ground state being condensed. The results are analyzed by a mean-field model and suggest that a large manifold of low-lying fragmented excited states can significantly impact the dynamics of trapped two-dimensional BECs. [4][5][6]. While three-dimensional trapped BECs have been extensively studied since their discovery, the static and time-dependent properties of their two-dimensional counterparts are comparatively less explored.One of the most popular scenarios studied with ultracold bosonic atoms, both experimentally and theoretically, is the splitting of a BEC by a central barrier into two spatially-disjoint clouds, e.g., Refs. [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. It is a common practice that in order to produce a fragmented BEC in the splitting process, the ground state must be fragmented. This renders high barriers and strong interaction strengths necessary. Previous works dealt with splitting of a BEC in one or three spatial dimensions. To the best of our knowledge, splitting of a BEC in two spatial dimensions has not been explored experimentally or theoretically on the many-body level.In the present work we investigate theoretically, on an accurate many-body level, the physics of splitting a twodimensional (2D) BEC. A natural approach is to exploit the 2D symmetry of the system. We thus split a circular BEC by a radial potential barrier, see Fig. 1a for an illustration. This would lead to two concentric clouds, unlike the above-discussed common way of splitting a BEC and, as we shall see below, enrich the physics of BEC splitting.By analyzing the many-body time-independent and time-dependent wavefunctions of the system, we construct both static and dynamic phase diagrams of the splitting process. Whereas the ground state is condensed for a wide range of parameters, the time-dependent splitting process leads to substantial fragmentation. We therefore demonstrate the dynamical fragmentation of a BEC, despite its ground state being fully condensed. The results imply that a large manifold of fragmented excited states can significantly impact the dynamics of 2D BECs.We consider a repulsive BEC with N = 100 bosons in the 2D circular trap shown in Fig. 1a. Throughout this work dimensionless units are used, such that the single-particle kinetic-energy operator readsT (r) = − 1 2 ∇ 2 r [22]. The explicit form of the one-body potential is given by V (r) = V trap (r) + V barrier (r). Here V trap (r) = {200e −(r−rc) 4 /2 , r ≤ r c = 9; 200, r > r c } is a flat trap which has the shape of "a crater" and V barrier (r) = 200e ...

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“…[7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. It is a common practice that in order to produce a fragmented BEC in the splitting process, the ground state must be fragmented.…”

mentioning

confidence: 99%

Breaking the resilience of a two-dimensional Bose-Einstein condensate to fragmentation

et al. 2014

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“…Consequently, atom chips form a clean and flexible environment for matter wave interferometry [15,16,17,18,19]. Recent experiments [1,2] created an atom interferometer by reflecting a BEC from a magnetic grating fabricated on such a chip.…”

Section: Introductionmentioning

confidence: 99%

Atom-chip diffraction of Bose-Einstein condensates: The role of interatomic interactions

Judd¹,

Scott²,

Fromhold³

2008

Phys. Rev. A

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We use supercomputer simulations to show that inter-atomic interactions can strongly affect the phase evolution of Bose-Einstein condensates that are diffracted from atom chips, thereby explaining recent experiments. Interactions broaden and depopulate non-central diffraction orders and so, counter-intuitively, they actually reduce the spatial width of the diffracted cloud. This means, more generally, that the experiments cannot be fully described by non-interacting theories and, consequently, interferometers that use many interacting atoms to enhance sensitivity require complex calibration. We identify device geometries required to approximate non-interacting behavior.

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“…This is exemplified by recent experiments on number or spin squeezing and entanglement between small atomic ensembles [4], which could serve as a resource for quantum metrology and quantum information science. Essential to such applications is the ability to precisely measure the populations of a pair of atomic ensembles in, for example, a double-well potential for Josephson physics or atom interferometry [2,[5][6][7], or the spin states of an atomic clock. Upon readout the interferometric phase can be mapped to a population difference and the two ensembles are imaged to different regions of a charge-coupled device (CCD) camera.…”

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confidence: 99%

Detection of small atom numbers through image processing

et al. 2010

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We demonstrate improved detection of small trapped atomic ensembles through advanced postprocessing and optimal analysis of absorption images. A fringe removal algorithm reduces imaging noise to the fundamental photon-shot-noise level and proves beneficial even in the absence of fringes. A maximum-likelihood estimator is then derived for optimal atom-number estimation and is applied to real experimental data to measure the population differences and intrinsic atom shot-noise between spatially separated ensembles each comprising between 10 and 2000 atoms. The combined techniques improve our signal-to-noise by a factor of 3, to a minimum resolvable population difference of 17 atoms, close to our ultimate detection limit.

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Condensate Splitting in an Asymmetric Double Well for Atom Chip Based Sensors

Cited by 89 publications

References 22 publications

Breaking the resilience of a two-dimensional Bose-Einstein condensate to fragmentation

Breaking the resilience of a two-dimensional Bose-Einstein condensate to fragmentation

Atom-chip diffraction of Bose-Einstein condensates: The role of interatomic interactions

Detection of small atom numbers through image processing

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