Quantum kinetic theory model of a continuous atom laser

Dennis, Graham; Hope, Joseph

doi:10.1103/physreva.86.013640

Cited by 4 publications

(6 citation statements)

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“…The total atom number per site N for the condensate plus thermal cloud determined by absorption imaging (Fig. 13(a)) decays with a half-life t 1/2 ∼ 0.9 ± 0.3 s, which is consistent with the three-body decay half-life for a pure condensate, t 1/2 ∼ 0.6 ± 0.2, estimated using N c (t) = N c (0)[1 + αN c (0)t] −5/4 , where α = L 3 (mω/ ) 12/5 14×15 1/5 π 2 a 6/5 s [27], L 3 = (5.8 ± 1.9) × 10 −30 cm 6 s −1 [11], a s = 5.3 nm and ω/2π = 2.40 kHz. The above half-life, t 1/2 ∼ 0.9 ± 0.3 s, is also similar (within about 10%) to the three-body decay half-life for an ultracold thermal cloud in which the six-times larger L 3 coefficient [11] is approximately compensated by the much smaller peak atom density for the thermal cloud (Fig.…”

Section: Rf Spectra For Various Holding Timessupporting

confidence: 86%

Radio-frequency spectroscopy of a linear array of Bose-Einstein condensates in a magnetic lattice

et al. 2015

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We report site-resolved radio-frequency spectroscopy measurements of Bose-Einstein condensates of 87 Rb atoms in about 100 sites of a one-dimensional (ID) 10-/rm-period magnetic lattice produced by a grooved magnetic film plus bias fields. Site-to-site variations of the trap bottom, atom temperature, condensate fraction, and chemical potential indicate that the magnetic lattice is remarkably uniform, with variations in the trap bottoms of only ± 0.4 mG. At the lowest trap frequencies (radial and axial frequencies of 1.5 kHz and 260 Hz, respectively), temperatures down to 0.16 /iK are achieved in the magnetic lattice, and at the smallest trap depths (50 kHz) condensate fractions up to 80% are observed. With increasing radial trap frequency (up to 20 kHz, or aspect ratio up to ~80) large condensate fractions persist, and the highly elongated clouds approach the quasi-1D Bose gas regime. The temperature estimated from analysis of the spectra is found to increase by a factor of about 5, which may be due to suppression of rethermalizing collisions in the quasi-1D Bose gas. Measurements for different holding times in the lattice indicate a decay of the atom number with a half-life of about 0.9 s due to three-body losses and the appearance of a high-temperature (~1.5 pK ) component which is attributed to atoms that have acquired energy through collisions with energetic three-body decay products.

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Section: Rf Spectra For Various Holding Timessupporting

confidence: 86%

Radio-frequency spectroscopy of a linear array of Bose-Einstein condensates in a magnetic lattice

et al. 2015

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“…A tantalizing prospect is to add an output coupler to extract a propagating matter-wave. This could be implemented by coherently transferring atoms to an untrapped state and would bring the long-sought CW atom laser finally within reach 15 , 45 . This prospect is especially compelling because our CW BEC is made of strontium, the element used in some of today’s best clocks 56 and the element of choice for future cutting-edge atom interferometers 20 – 24 , 57 , 58 .…”

Section: Discussionmentioning

confidence: 99%

“…The corresponding phase-space flux is (ref. 45 ), in which ħ is the reduced Planck constant, k B the Boltzmann constant and ω R i /2π are the reservoir trap frequencies.…”

Section: Methodsmentioning

confidence: 99%

Continuous Bose–Einstein condensation

Chen

Escudero

Minář

et al. 2022

Nature

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Bose–Einstein condensates (BECs) are macroscopic coherent matter waves that have revolutionized quantum science and atomic physics. They are important to quantum simulation1 and sensing2,3, for example, underlying atom interferometers in space4 and ambitious tests of Einstein’s equivalence principle5,6. A long-standing constraint for quantum gas devices has been the need to execute cooling stages time-sequentially, restricting these devices to pulsed operation. Here we demonstrate continuous Bose–Einstein condensation by creating a continuous-wave (CW) condensate of strontium atoms that lasts indefinitely. The coherent matter wave is sustained by amplification through Bose-stimulated gain of atoms from a thermal bath. By steadily replenishing this bath while achieving 1,000 times higher phase-space densities than previous works7,8, we maintain the conditions for condensation. Our experiment is the matter wave analogue of a CW optical laser with fully reflective cavity mirrors. This proof-of-principle demonstration provides a new, hitherto missing piece of atom optics, enabling the construction of continuous coherent-matter-wave devices.

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“…We expect this is a reasonable approximation in steady state if we imagine that we can replenish thermal atoms at a constant rate while undergoing continuous cooling, e.g. [19,22]. The stationary incoherent region thus continuously replenishes the coherent region through Bose-stimulated collisions.…”

Section: Model Of a Continuously Pumped Atom Lasermentioning

confidence: 95%

“…Many theoretical proposals for continuously-pumped operation have been made, using either evaporative cooling [20][21][22] or spontaneous emission [23][24][25], A number of studies have already considered the properties of a CW atom laser at zero temperature [26][27][28][29][30][31][32][33][34][35][36]. However, one of the most likely experimental routes to a true CW atom laser will involve replenishing the BEC via cooling from a reservoir containing thermal atoms so that the condensate mode is maintained in a steady state via Bose-stimulated collisions, similar to the experiment of Stellmer et al [19].…”

Section: Introductionmentioning

confidence: 99%

Coherence and linewidth of a continuously pumped atom laser at finite temperature

2015

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(2015) Coherence and linewidth of a continuously pumped atom laser at finite temperature. Physical Review A, 92 (1). p. 3605. ISSN 10503605. ISSN -2947 This version is available from Sussex Research Online: http://sro.sussex.ac.uk/66132/ This document is made available in accordance with publisher policies and may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the URL above for details on accessing the published version. Copyright and reuse:Sussex Research Online is a digital repository of the research output of the University.Copyright and all moral rights to the version of the paper presented here belong to the individual author(s) and/or other copyright owners. To the extent reasonable and practicable, the material made available in SRO has been checked for eligibility before being made available.Copies of full text items generally can be reproduced, displayed or performed and given to third parties in any format or medium for personal research or study, educational, or not-for-profit purposes without prior permission or charge, provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way.PHYSICAL REVIEW A 92, 013605 (2015) Coherence and linewidth of a continuously pumped atom laser at finite temperature A continuous-wave atom laser formed by the outcoupling of atoms from a trapped Bose-Einstein condensate (BEC) potentially has a range of metrological applications. However, in order for the device to be truly continuous, a mechanism to replenish the atoms in the BEC is required. Here we calculate the temporal coherence properties of a continuously pumped atom laser beam outcoupled from a trapped Bose-Einstein condensate that is replenished from a reservoir at finite temperature. We find that the thermal fluctuations of the condensate can significantly decrease the temporal coherence of the output beam due to atomic interactions between the trapped BEC and the beam, and this can impact the metrological usefulness of the device. We demonstrate that a Raman outcoupling scheme imparting a sufficient momentum kick to the atom laser beam can lead to a significantly reduced linewidth.

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Quantum kinetic theory model of a continuous atom laser

Cited by 4 publications

References 51 publications

Radio-frequency spectroscopy of a linear array of Bose-Einstein condensates in a magnetic lattice

Radio-frequency spectroscopy of a linear array of Bose-Einstein condensates in a magnetic lattice

Continuous Bose–Einstein condensation

Coherence and linewidth of a continuously pumped atom laser at finite temperature

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