Random to Chaotic Statistic Transformation in Low-Field Fano-Feshbach Resonances of Cold Thulium Atoms

V A Khlebnikov; D A Pershin; V V Tsyganok; E T Davletov; I S Cojocaru; E S Fedorova; A A Buchachenko; A V Akimov

doi:10.1103/PhysRevLett.123.213402

Random to Chaotic Statistic Transformation in Low-Field Fano-Feshbach Resonances of Cold Thulium Atoms

Phys Rev Lett. 2019 Nov 22;123(21):213402. doi: 10.1103/PhysRevLett.123.213402.

Authors

V A Khlebnikov¹, D A Pershin^{1

2}, V V Tsyganok^{1

2}, E T Davletov^{1

2}, I S Cojocaru^{1

3}, E S Fedorova^{1

4}, A A Buchachenko^{5

6}, A V Akimov^{1

4

3}

Affiliations

¹ Russian Quantum Center, Business center "Ural," 100A Novaya street, Skolkovo, Moscow, 143025, Russia.
² Moscow Institute of Physics and Technology, Institutskii lane 9, Dolgoprudny, Moscow region, 141700, Russia.
³ Texas A&M University, 4242 TAMU, College Station, Texas 77843, USA.
⁴ PN Lebedev Institute RAS, Leninsky prospekt 53, Moscow, 119991, Russia.
⁵ Skolkovo Institute of Science and Technology, Skolkovo Innovation Center, Moscow 143026, Russia.
⁶ Institute of Problems of Chemical Physics RAS, Chernogolovka, Moscow Region 142432, Russia.

PMID: 31809162
DOI: 10.1103/PhysRevLett.123.213402

Abstract

Here, we report on the observation of a random to chaotic temperature transformation in the statistics of nearest-neighbor spacings of Fano-Feshbach resonances in the ultracold polarized gas of thulium-169 atoms. We associate this transformation to the appearance of so-called d resonances as well as the shift of other resonances with the temperature. In addition to this statistical change, it has been observed that the characters of s- and d-resonance temperature shifts are quite different: s resonances experience almost no shift or even negative shift with the temperature, while d resonances experience an obvious positive shift. The sign change was attributed to the difference in polarizability of Feshbach molecules and free thulium atoms. In addition, careful analysis of the broad Fano-Feshbach resonances enabled the determination of the sign of thulium's background scattering length. A rethermalization experiment made it possible to estimate a length value of a_{bg}=+144±38 a.u. This indicates that thulium atoms are suitable for achieving Bose-Einstein condensation.