Enhanced quantum spin fluctuations in a binary Bose-Einstein condensate

Year: 2018

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

Autors Affiliation: Univ Trento, INO CNR BEC Ctr, I-38123 Povo, Italy; Univ Trento, Dipartimento Fis, I-38123 Povo, Italy; Univ Massachusetts, Dept Math & Stat, Amherst, MA 01003 USA; 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: 23602-1  to: 23602-11

More Information: We thank D. Baillie, T. Bienaime, P. B. Blakie, R. Carretero-Gonzalez, G. Ferrari, S. I. Mistakidis, A. Recati, and C. Qu for useful and stimulating discussions. R.N.B. acknowledges the EU QUIC project and Provincia Autonoma di Trento for financial support. P.G.K. acknowledges the support of Grants No. NSF-DMS-1312856 and No. PHY-1602994, from the ERC under FP7, Marie Curie Actions, People, International Research Staff Exchange Scheme (IRSES-605096), and the Stavros Niarchos Foundation via the Greek Diaspora Fellowship Program. C. T. acknowl edges support by Los Alamos National Laboratory, which is operated by LANS, LLC for the NNSA of the U. S. DOE and, specifically, Contract No. DEAC52-06NA25396.
KeyWords: Gas; Mixture; Separation; Droplets; Dynamics
DOI: 10.1103/PhysRevA.97.023602

ImpactFactor: 2.907
Citations: 11
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