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Structure of the mean-field yrast spectrum of a two-component Bose gas in a ring: Role of the interaction asymmetry

Hui Tang1,2,*, Guan-Hua Huang3,1,*, Shizhong Zhang2,4, Zhigang Wu1,†, and Eugene Zaremba5

  • *These authors contributed equally to this work.
  • †Contact author: wuzhigang@quantumsc.cn
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Phys. Rev. A 114, 023309 – Published 7 August, 2026

DOI: https://doi.org/10.1103/79df-2dzt

Abstract

The mean-field yrast spectrum of an SU(2)-symmetric two-component Bose gas confined to a ring geometry is known to exhibit an intricate nonanalytic structure that is absent in single-component systems. In particular, due to the interplay between the species concentration and the atomic interactions, a sequence of plane-wave states can emerge as yrast states at fractional values of the angular momentum per particle. This behavior stands in sharp contrast to the single-component case, where plane-wave states occur only at integer angular momenta. In this paper, we investigate how the structure of the yrast spectrum in a two-component Bose gas is modified by interaction asymmetry. By numerically solving the coupled Gross-Pitaevskii equations for propagating soliton states, we compute the mean-field yrast spectrum, and in particular, determine the critical curves associated with the emergence of various plane-wave yrast states. We find that both the behavior of these critical curves and the mechanisms by which plane-wave yrast states arise depend sensitively on the relative strengths of the inter and intracomponent interactions. When the intracomponent interaction is weaker, the plane-wave yrast states replace soliton states through a continuous evolution, as in the SU(2)-symmetric case, although the conditions for their existence become more restrictive. In contrast, when the intracomponent interaction is stronger, plane-wave yrast states may emerge by overtaking soliton states via branch crossings, and their stability is significantly enhanced. Our results have important implications for the existence and stability of persistent currents in asymmetric, two-component Bose gases.

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Phys. Rev. A 114, 023309– Published 7 August, 2026
  • Received 7 April 2026
  • Accepted 22 July 2026
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