Enhanced quantum spin fluctuations in a binary Bose-Einstein condensate

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 (anti-bunching) 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.

12 pages (main body ~ 7 pages), 6 figures

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Cited by in corpus (8)

• Correlation Effects in the Quench-Induced Phase Separation Dynamics of a Two-Species Ultracold Quantum Gas
• Miscibility and stability of dipolar bosonic mixtures
• Harmonically trapped Bose-Bose mixtures: a quantum Monte Carlo study
• Miscibility regimes in a ${}^{23}$Na-${}^{39}$K quantum mixture
• Miscibility of Binary Bose-Einstein Condensates with $p$-wave Interaction
• Bogoliubov spectrum and the dynamic structure factor in a quasi-two-dimensional spin-orbit coupled BEC
• Excitation spectrum of vortex-lattice modes in a rotating condensate with a density-dependent gauge potential
• Phase diagram of two-component mean-field Bose mixtures