Very-high-precision bound-state spectroscopy near a<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow /><mml:mrow><mml:mn>85</mml:mn></mml:mrow></mml:msup></mml:mrow><mml:mi mathvariant="normal">Rb</mml:mi></mml:math>Feshbach resonance

Claussen, N. R.; Kokkelmans, Sjjmf Servaas; Thompson, S.T.; Donley, E. A.; Hodby, E.; Wieman, C. E.

doi:10.1103/physreva.67.060701

Cited by 133 publications

(237 citation statements)

References 32 publications

(63 reference statements)

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“…We characterize and pre-correct for induced currents from mutual inductances between these coils and the magnetic trap coils as well as eddy currents in surrounding conductors. Taking into account roughly equal contributions from uncertainty in our magnetic field and the uncertainty in the Feshbach resonance location B 0 [31], we estimate that our experiments are within ± 50 mG of the Feshbach resonance, which corresponds to |a| > 95, 000 a 0 .…”

Section: Magnetic-field Controlmentioning

confidence: 99%

“…1a) begin with a 85 Rb BEC of between 5 − 7 × 10 4 atoms confined in a 10 Hz spherical magnetic trap [30]. The magnetic field, B, is set approximately 8 G above the 85 Rb Feshbach resonance at B 0 = 155.04 G [31]. This sets the initial a to 142 a 0 , which gives the BEC a Thomas-Fermi density distribution with an average density n = 5.5(3) × 10 12 cm −3 .…”

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confidence: 99%

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Universal dynamics of a degenerate unitary Bose gas

et al. 2014

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From neutron stars to high-temperature superconductors, strongly interacting many-body systems at or near quantum degeneracy are a rich source of intriguing phenomena. The microscopic structure of the first-discovered quantum fluid, superfluid liquid helium, is difficult to access due to limited experimental probes. While an ultracold atomic Bose gas with tunable interactions (characterized by its scattering length, a) had been proposed as an alternative strongly interacting Bose system [1][2][3][4][5][6][7][8] , experimental progress [9][10][11][12] has been limited by its short lifetime. Here we present time-resolved measurements of the momentum distribution of a Bose-condensed gas that is suddenly jumped to unitarity, i.e. to a = ∞. Contrary to expectation, we observe that the gas lives long enough to permit the momentum to evolve to a quasi-steady-state distribution, consistent with universality, while remaining degenerate. Investigations of the time evolution of this unitary Bose gas may lead to a deeper understanding of quantum many-body physics.A powerful feature of atom gas experiments that provides access to these new regimes is the ability to change the interaction strength using a magnetic-field Feshbach resonance [13]. In particular, at the resonance location, a is infinite. For atomic Fermi gases [14][15][16][17][18][19][20], accessing this regime by adiabatically changing a led to the achievement of superfluids of paired fermions and enabled investigation of the crossover from superfluidity of weakly bound pairs, analogous to the Bardeen-Cooper-Schrieffer (BCS) theory of superconductors, to Bose-Einstein condensation (BEC) of tightly bound molecules [16,17]. For bosonic atoms, however, this route to strong interactions is stymied by the fact that three-body inelastic collisions increase as a to the fourth power [21][22][23]. This circumstance has limited experimental investigation of Bose gases with increasing interaction strength to studying either non-quantum-degenerate gases [24,25] or BECs with modest interaction strengths (na 3 < 0.008, where n is the atom number density) [9][10][11][12].The problem is that the loss rate scales as n 2 a 4 while the equilibration rate scales as na 2 v, where v is the average velocity. Thus, it would seem that the losses will always dominate as a is increased to ∞. Even if we were to forsake thermal equilibrium and suddenly change a in order to project a weakly interacting BEC onto strong interactions [12,[26][27][28], one might expect that three-body losses would still dominate the ensuing dynamics for large a. In this work, however, we use this approach to take a BEC to the unitary gas regime, and we observe dynamics that in fact saturate on a timescale shorter than that set by three-body losses and that exhibit universal scaling with density.

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Section: Magnetic-field Controlmentioning

confidence: 99%

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confidence: 99%

Universal dynamics of a degenerate unitary Bose gas

et al. 2014

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“…In other situations a bg can be large and negative, indicating that the interaction potential has a virtual state near threshold. Examples here are 85 Rb with a bg = −443a 0 [14], and 6 Li where a bg Ϸ −2000a 0 [29,30]. In these cases, the nonresonant description of the background scattering process is not correct.…”

Section: ͑1͒mentioning

confidence: 99%

“…When the magnetic field is changed during an experiment, (quasibound) molecules can be formed [10][11][12] while sweeping through the resonance. At JILA, coherent oscillations between atoms and molecules have been observed by applying two magneticfield "Ramsey" pulses close to resonance [13,14]. The oscillation frequency was directly related to the binding energy of the molecules.…”

Section: Introductionmentioning

confidence: 99%

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Feshbach resonances with large background scattering length: Interplay with open-channel resonances

et al. 2004

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Bright Solitary Matter Waves: Formation, Stability and Interactions

Billam

Marchant

Cornish

et al. 2012

Progress in Optical Science and Photonics

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In recent years, bright soliton-like structures composed of gaseous Bose-Einstein condensates have been generated at ultracold temperature. The experimental capacity to precisely engineer the nonlinearity and potential landscape experienced by these solitary waves offers an attractive platform for fundamental study of solitonic structures. The presence of three spatial dimensions and trapping implies that these are strictly distinct objects to the true soliton solutions. Working within the zero-temperature mean-field description, we explore the solutions and stability of bright solitary waves, as well as their interactions. Emphasis is placed on elucidating their similarities and differences to the true bright soliton. The rich behaviour introduced in the bright solitary waves includes the collapse instability and symmetry-breaking collisions. We review the experimental formation and observation of bright solitary matter waves to date, and compare to theoretical predictions. Finally we discuss the current state-of-the-art of this area, including beyond-mean-field descriptions, exotic bright solitary waves, and proposals to exploit bright solitary waves in interferometry and as surface probes. * nick.parker@ncl.ac.uk arXiv:1209.0560v1 [cond-mat.quant-gas] 4 Sep 2012• A sophisticated toolbox based on atomic physics allows almost arbitrary shapes of confining potentials to be constructed, for example, waveguides to steer the wavepackets, systems of reduced dimensionality, and disordered and periodic potential landscapes.• This toolbox also enables the interactions (i.e. the nonlinearity) to be changed effectively from infinitely attractive, through zero, to infinitely repulsive via the exploitation of Feshbach resonances. Moreover, one can employ atoms such as 52 Cr which feature permanent magnetic dipole moments; this introduces long-range atom-atom interactions, i.e. nonlocal nonlinearity, into the system [13].• The condensate density can be imaged directly with high contrast. While this is most commonly performed via destructive techniques based on optical absorption, non-destructive imaging techniques are also possible, e.g. phase-contrast imaging [3]. The phase of the condensate can also be mapped out in space and time via interferometric techniques [14].• Bright solitary waves, which typically exist as small BECs, are mesoscopic quantum systems. This scale allows interfacing of the robust and well-established mean-field description of BECs with more sophisticated models that incorporate thermal and quantum effects [4].• The precision and control offered by BECs makes them an attractive system in general for application in ultra-precise force detection and quantum information. For these applications, bright solitary waves offer further merits through their self-trapped, highly-localized form. The mean-field Gross-Pitaevskii equationOur theoretical analysis will be based upon the well-established Gross-Pitaevskii equation, which is a wave equation for the classical field of the many-body wavefunction [3][4][5]. ...

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Very-high-precision bound-state spectroscopy near a85RbFeshbach resonance

Cited by 133 publications

References 32 publications

Universal dynamics of a degenerate unitary Bose gas

Universal dynamics of a degenerate unitary Bose gas

Feshbach resonances with large background scattering length: Interplay with open-channel resonances

Bright Solitary Matter Waves: Formation, Stability and Interactions

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