Scientific Results

Enhanced quantum spin fluctuations in a binary Bose-Einstein condensate

Year: 2018

Authors: Bisset RN., Kevrekidis PG., Ticknor C.

Autors Affiliation: [Bisset, R. N.] INO CNR BEC Ctr, I-38123 Povo, Italy and Univ Trento, Dipartimento Fis, I-38123 Povo, Italy.
[Kevrekidis, P. G.] Univ Massachusetts, Dept Math & Stat, Amherst, MA 01003 USA.
[Ticknor, C.] Los Alamos Natl Lab, Theoret Div, Los Alamos, NM 87545 USA.

Abstract: For quantum fluids, the role of quantum fluctuations may be significant in several regimes such as when the dimensionality is low, the density is high, the interactions are strong, or for low particle numbers. In this paper, we propose a fundamentally different regime for enhanced quantum fluctuations without being restricted by any of the above conditions. Instead, our scheme relies on the engineering of an effective attractive interaction in a dilute, two-component Bose-Einstein condensate (BEC) consisting of thousands of atoms. In such a regime, the quantum spin fluctuations are significantly enhanced (atom bunching with respect to the noninteracting limit) since they act to reduce the interaction energy, a remarkable property given that spin fluctuations are normally suppressed (antibunching) at zero temperature. In contrast to the case of true attractive interactions, our approach is not vulnerable to BEC collapse. We numerically demonstrate that these quantum fluctuations are experimentally accessible by either spin or single-component Bragg spectroscopy, offering a useful platform on which to test beyond-mean-field theories. We also develop a variational model and use it to analytically predict the shift of the immiscibility critical point, finding good agreement with our numerics.

Journal/Review: PHYSICAL REVIEW A

Volume: 97 (2)      Pages from: 023602-1  to: 023602-11

KeyWords: gases; mixture; atoms; temperature; separation
DOI: 10.1103/PhysRevA.97.023602

Citations: 4
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