Dynamics of Three-Body Correlations in Quenched Unitary Bose Gases

Colussi, V. E.; Corson, John; D'Incao, Jose

doi:10.1103/physrevlett.120.100401

Cited by 47 publications

(97 citation statements)

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“…[11,12] and is theoretically motivated by the universal substitution a 4 → a 4 eff in the scaling law of K eff 3 for shallow dimers as was suggested in Refs. [17,45]. For clarity, the universal scaling n 2/3 was found to be valid only for t hold 4t n , for longer time the loss rate scales as n 26/9 , consistent with the results for a thermal gas at unitarity [46,47] and beyond the limit of validity of our model, as discussed in Sec.…”

Section: Modeling Three-body Lossessupporting

confidence: 88%

“…[11]. Understanding the role of the Efimov effect [17,18] and dynamics of higher-order correlations [19][20][21] in the quenched unitary Bose gas remains, however, an ongoing pursuit in the community.…”

Section: Introductionmentioning

confidence: 99%

“…To estimate the potential relevance of Efimov trimers, we follow Refs. [17,18] and compare the Fermi scale with the size of the nearby first-excited trimer R (1) 3b = (1 + s 2 0 ) 1/2 e π/s0 /(3/2) 1/2 κ * , where s 0 ≈ 1.00624 and κ * = 0.226/r vdW is the universal three-body parameter [6][7][8]. For the density range considered in Fig.…”

mentioning

confidence: 99%

“…including losses [Eqs (5),(17),. and(18)] for the39 K 425 Feshbach resonance at B = 402 G with a bg = −29a 0 , 426 ∆B = −52 G, andā = 61.7a 0[1].…”

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confidence: 99%

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Pair formation in quenched unitary Bose gases

2019

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We study a degenerate Bose gas quenched to unitarity by solving a many-body model including three-body losses and correlations up to second order. As the gas evolves in this strongly interacting regime, the buildup of correlations leads to the formation of extended pairs bound purely by manybody effects, analogous to the phenomenon of Cooper pairing in the BCS regime of the Fermi gas. Through fast sweeps away from unitarity, we detail how the correlation growth and formation of bound pairs emerge in the fraction of unbound atoms remaining after the sweep, finding quantitative agreement with experiment. We comment on the possible role of higher-order effects in explaining the deviation of our theoretical results from experiment for slower sweeps and longer times spent in the unitary regime. though these findings, combined with studies of loss dy-52 namics in Refs. [10-12], are consistent with the univer-53 sality hypothesis, a macroscopic population of Efimov 54 trimers was observed in Ref. [11]. Understanding the 55 role of the Efimov effect [17, 18] and dynamics of higher-56 order correlations [19-21] in the quenched unitary Bose 57 gas remains however an ongoing pursuit in the commu-58 nity. 59 60The difficulties of probing the system at unitarity re-61 quire that experiments return to the more stable and 62 better-understood weakly-interacting regime. During the 63 course of the experiment, we have to distinguish differ-64 ent types of atomic pairs: (i) pairs of atoms with op-65 posite momentum, analogous to Cooper pairs in Fermi 66 gases, (ii) embedded dimers at unitarity whose size is de-67 termined by the mean interparticle separation, and (iii) 68 specific ramp, we find a molecular fraction ∼ 10%, which 472 is compatible with the experimental estimate in Ref. [12]. 473 By comparing three values A = {0.28, 0.20, 0.18} to the 474 0.3 µs/G experimental data we find that A = 0.20 pro-475 vides the best fit of the experimental results over the full 476 range of t hold considered in this work. For the slower 6 477 µs/G ramp, we find that A = 0.20 gives good agreement 478 at early-times until roughly t hold 0.5t n . We discuss 479 possible sources of this discrepancy at longer t hold at the 480 conclusion of this section. 481 Our results for N free over a range of 1/R are com-482 pared against the experimental findings in Ref. [12] as 483 shown in Fig. 5. The results shown in Fig. 5 are at 484 fixed t hold = 1.9t n , nearing the limit of validity of our 485 model [see Sec. II A]. The intuitive picture, discussed 486 in Secs. II B, II C and illustrated in Fig. 2 provides a 487 way to understand our results particularly at this later 488 time where the bound pairs at unitarity play a dom-489 inant role [see Fig. 3]. For smaller ramp rates, the 490 largest values of N free shown in Fig. 5 result from the 491 fast-sweep projection occurring further away from unitar-492 ity where the overlap between embedded dimers (φ D (k)) 493 with molecules (φ * (k)) becomes minimal. We find good 494 agreement with experiment only ...

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Section: Modeling Three-body Lossessupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

“…including losses [Eqs (5),(17),. and(18)] for the39 K 425 Feshbach resonance at B = 402 G with a bg = −29a 0 , 426 ∆B = −52 G, andā = 61.7a 0[1].…”

mentioning

confidence: 99%

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Pair formation in quenched unitary Bose gases

2019

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“…Theoretically, a prediction for the gradual growth of C 3 in a uniform degenerate Bose gas quenched to unitary was made in Ref. [17] where a coherent beating phenomenon at the frequency of Efimov states was observed.…”

Section: Introductionmentioning

confidence: 99%

Two-Body and Three-Body Contacts for Three Bosons in the Unitary Regime: Analytic Expressions and Limiting Forms

Colussi

2019

Atoms

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The two and three-body contacts are central to a set of univeral relations between microscopic few-body physics within an ultracold Bose gas and its thermodynamical properties. They may also be defined in trapped few-particle systems, which is the subject of this work. In this work, we focus on the unitary three-body problem in a trap, where interactions are as strong as allowed by quantum mechanics. We derive analytic results for the two and three-body contacts in this regime and compare with existing limiting expressions and previous numerical studies.

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