Feshbach spectroscopy and dual-species Bose-Einstein condensation of Na23−K39 mixtures

Abstract

We present measurements of interspecies Feshbach resonances and subsequent creation of dualspecies Bose-Einstein condensates of 23 Na and 39 K. We prepare both optically trapped ensembles in the spin state |f = 1, m f = −1 and perform atom loss spectroscopy in a magnetic field range from 0 to 700 G. The observed features include several s-wave poles and a zero crossing of the interspecies scattering length as well as inelastic two-body contributions in the M = mNa+mK = −2 submanifold. We identify and discuss the suitability of different magnetic field regions for the purposes of sympathetic cooling of 39 K and achieving dual-species degeneracy. Two condensates are created simultaneously by evaporation at a magnetic field of about 150 G, which provides sizable intra-and interspecies scattering rates needed for fast thermalization. The impact of the differential gravitational sag on the miscibility criterion for the mixture is discussed. Our results serve as a promising starting point for the magnetoassociation into quantum degenerate 23 Na 39 K Feshbach molecules.arXiv:1709.03796v2 [cond-mat.quant-gas]

The mixing-demixing phase diagram of ultracold heteronuclear mixtures in a ring trimer

“…In this prospective, 23 Na + 39 K constitutes an ideal mixture. The spin mixture | f = 1, m f = −1 Na + | f = 1, m f = −1 K , where f is the atomic total angular momentum and m f its projection on the quantization axis, has been recently doubly Bose-condensed and presents a favorable window of magnetic field (from 90 to 150 G) where the combination of two intra-and two inter-species resonances allow for a smooth tuning of the scattering lengths 43 (see left panel of Fig. 6).…”

Harmonically trapped Bose–Bose mixtures: a quantum Monte Carlo study

“…Ultracold Bose-Bose mixtures are currently produced in many laboratories offering the unique possibility of studying the interplay between two Bose-Einstein condensates (BEC) [1][2][3][4][5][6][7][8][9][10][11][12]. The high tunability of the atomic interactions, thanks to the presence of Feshbach resonances, and the combinations between different elements, different isotopes or different hyperfine levels enrich dramatically the interest in its physical study.…”

A pathway to ultracold bosonic 23Na39K ground state molecules

“…The spectroscopic studies presented in this work are based on the preparation of an ultracold mixture of 23 Na+ 39 K. A description of the experimental setup can be found in [16,18,19]. Details of the experimental procedure can be found in [20,21]. In the following, we briefly summarize the main experimental steps.…”