Universal prethermal dynamics of Bose gases quenched to unitarity

Eigen, Christoph; Glidden, Jake; Lopes, Raphaël; Cornell, Eric A.; Smith, Robert P.; Hadzibabic, Zoran

doi:10.1038/s41586-018-0674-1

Cited by 165 publications

(189 citation statements)

References 40 publications

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“…We model a uniform gas of identical spinless bosons interacting via pairwise interactions described by the single-channel many-body Hamiltonian [10][11][12][13]30]. To fix the free parameters of the separable potential, we first set the strength of the potential, g = U 0 Γ, where U 0 = 4π 2 a/m and Γ = (1 − 2aΛ/π) −1 , to reproduce the exact two-body T matrix in the zero-energy limit [20,31].…”

Section: A Many-body Equationsmentioning

confidence: 99%

“…Time-resolved studies of the single-particle momentum distribution in Ref. [13] revealed that the theoretically predicted prethermal state [14][15][16] transitions to steady state prior to being overcome by heating. Although * s.musolino@tue.nl these findings, combined with studies of loss dynamics in Refs.…”

Section: Introductionmentioning

confidence: 99%

“…II C. It is interesting to note the analogy of pair formation in the quenched unitary Bose gas to pair formation in the unitary Fermi gas [23], which is at the center of the so-called BCS-BEC crossover. When entering this crossover from the Bardeen-Cooper-Schrieffer (BCS) side, fermionic pairs, loosely bound by the medium, smoothly evolve into tightly bound molecules that are stable even without the medium, arXiv:1904.00908v2 [cond-mat.quant-gas] 11 Jul 2019 n the possible role of higher-order effects in explaining experiment for slower sweeps and longer times spent in of osace- / [10][11][12][13]. First, the magnetic field B is ramped suddenly towards the resonant value B 0 , taking the system from the weakly-interacting (na 3 < 1) to the unitary regime na 3 1 (shaded region).…”

Section: Introductionmentioning

confidence: 99%

“…Schematic representation of the experimental protocol used in Refs. [10][11][12][13]. First, the magnetic field B is ramped suddenly towards the resonant value B0, taking the system from the weakly interacting (na 3 < 1) to the unitary regime na 3 1 (shaded region).…”

Section: Introductionmentioning

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: A Many-body Equationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Pair formation in quenched unitary Bose gases

2019

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“…In addition, it is worth mentioning other aspects of universality arising in non-equilibrium dynamics, which have been recently identified in Refs. [45][46][47]. Despite this progress, various aspects of non-equilibrium dynamics in isolated and open many-body quantum systems remain to be explored [32,33].…”

Section: Introductionmentioning

confidence: 99%

Quantum Kibble-Zurek physics in long-range transverse-field Ising models

2019

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We analyze the quantum phase transitions taking place in a one-dimensional transverse field Ising model with long-range couplings that decay algebraically with distance. We are interested in the Kibble-Zurek universal scaling laws emerging in non-equilibrium dynamics and in the potential for the unambiguous observation of such behavior in a realistic experimental setup based on trapped ions. To this end, we determine the phase diagram of the model and the critical exponents characterizing its quantum phase transitions by means of density-matrix renormalization group calculations and finite-size scaling theory, which allows us to obtain good estimates for different range of ferro-and antiferromagnetic interactions. Beyond critical equilibrium properties, we tackle a non-equilibrium scenario in which quantum Kibble-Zurek scaling laws may be retrieved. Here it is found that the predicted non-equilibrium universal behavior, i.e. the scaling laws as a function of the quench rate and critical exponents, can be observed in systems comprising an experimentally feasible number of spins. Finally, a scheme is introduced to simulate the algebraically decaying couplings accurately by means of a digital quantum simulation with trapped ions. Our results suggest that quantum Kibble-Zurek physics can be explored and observed in state-of-the-art experiments with trapped ions realizing long-range Ising models.

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