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Roton-mediated soliton bound states in binary dipolar condensates

R. M. V. Röhrs and R. N. Bisset

  • Universität Innsbruck, Fakultät für Mathematik, Informatik und Physik, Institut für Experimentalphysik, 6020 Innsbruck, Austria

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Phys. Rev. A 113, 033311 – Published 19 March, 2026

DOI: https://doi.org/10.1103/dddk-qym1

Abstract

We investigate the formation of bound states between dark-antidark solitary waves in two-component dipolar Bose-Einstein condensates. The excitation spectrum contains density and spin branches and a rotonic feature of the spin branch enables long-range soliton interactions, giving rise to multiple bound states for a single pair, each with a distinct separation. We show that these bound states originate from periodic modulations of the intersoliton potential, while individual solitons are surrounded by spatial spin-density oscillations. Both features provide direct signatures of the spin roton. Collisions between unbound solitons probe this potential, with dipolar interactions enforcing universal bouncing at low velocities, independent of soliton sign, whereas nondipolar solitons may either transmit or bounce. This distinct behavior offers a realistic path to confirming spin rotons experimentally.

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Phys. Rev. A 113, 033311– Published 19 March, 2026
  • Received 4 October 2025
  • Accepted 18 February 2026
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