Relaxation of bosons in one dimension and the onset of dimensional crossover

Year: 2020

Authors: Li C., Zhou TW., Mazets I., Stimming HP., Moller FS., Zhu ZJ., Zhai YY., Xiong W., Zhou XJ., Chen XZ., Schmiedmayer J.

Autors Affiliation: Peking Univ, Sch Elect Engn & Comp Sci, Beijing 100871, Peoples R China; TU Wien, Atominst, Vienna Ctr Quantum Sci & Technol VCQ, Vienna, Austria; INO CNR Ist Nazl Ott CNR, Sez Sesto Fiorentino, I-50019 Sesto Fiorentino, Italy; Univ Wien, Fak Math, Res Platform MMM Math Magnetism Mat, A-1090 Vienna, Austria; Swiss Fed Inst Technol, Inst Quantum Elect, CH-8093 Zurich, Switzerland; Beihang Univ, Sci & Technol Inertial Lab, Beijing 100191, Peoples R China.

Abstract: We study ultra-cold bosons out of equilibrium in a one-dimensional (1D) setting and probe the breaking of integrability and the resulting relaxation at the onset of the crossover from one to three dimensions. In a quantum Newton’s cradle type experiment, we excite the atoms to oscillate and collide in an array of 1D tubes and observe the evolution for up to 4.8 seconds (400 oscillations) with minimal heating and loss. By investigating the dynamics of the longitudinal momentum distribution function and the transverse excitation, we observe and quantify a two-stage relaxation process. In the initial stage single-body dephasing reduces the 1D densities, thus rapidly drives the 1D gas out of the quantum degenerate regime. The momentum distribution function asymptotically approaches the distribution of quasimomenta (rapidities), which are conserved in an integrable system. In the subsequent long time evolution, the 1D gas slowly relaxes towards thermal equilibrium through the collisions with transversely excited atoms. Moreover, we tune the dynamics in the dimensional crossover by initializing the evolution with different imprinted longitudinal momenta (energies). The dynamical evolution towards the relaxed state is quantitatively described by a semiclassical molecular dynamics simulation.

Journal/Review: SCIPOST PHYSICS

Volume: 9 (4)      Pages from: 058-1  to: 058-29

More Information: X.C. acknowledges the support by the National Natural Science Foundation of China (Grant No. 11920101004, 91736208). J.S. acknowledges the support by the Austrian Science Fund (FWF) via the SFB 1225 ISOQUANT (I 3010-N27). I.M. and H.-P. S. acknowledge the support by the Wiener Wissenschafts-und Technologiefonds (WWTF) via Grant No. MA16-066 (SEQUEX) and by the Austrian Science Fund (FWF) via Grant SFB F65 (Complexity in PDE systems). X.Z. acknowledges the support by the National Key Research and Development Program of China (Grant No. 2016YFA0301501). F.M. acknowledges the support by the Doctoral Program CoQuS.
KeyWords: INTERACTING BOSE-GAS; BRAGG SCATTERING; ATOMS; THERMALIZATION
DOI: 10.21468/SciPostPhys.9.4.058

Citations: 22
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