https://doi.org/10.1140/epjd/s10053-026-01176-1
Research - Atoms, Molecules, Ions, and Clusters
Critical speed of a binary superfluid of light
1
Université Paris-Saclay, CNRS, LPTMS, 91405, Orsay, France
2
Université Côte d’Azur, CNRS, INPHYNI, Nice, France
3
Institut Universitaire de France (IUF), Paris, France
4
Sorbonne Université, ENS paris, Collège de France, Université PSL, CNRS, Laboratoire Kastler Brossel, F-75005, Paris, France
a
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Received:
24
January
2026
Accepted:
25
April
2026
Published online:
31
May
2026
Abstract
We theoretically study the critical speed for superfluid flow of a two-dimensional miscible binary superfluid of light past a polarization-sensitive optical obstacle. This speed corresponds to the maximum mean flow velocity below which dissipation is absent. In the weak-obstacle regime, linear-response theory shows that the critical speed is set by Landau’s criterion applied to the density and spin Bogoliubov modes, whose relative ordering can be inverted due to saturation of the optical nonlinearity. For obstacles of arbitrary strength and large spatial extent, we determine the critical speed from the conditions for strong ellipticity of the stationary hydrodynamic equations within the hydraulic and incompressible approximations. Numerical simulations in this regime reveal that the breakdown of superfluidity is initiated by the nucleation of vortex-antivortex pairs for an impenetrable obstacle and of Jones-Roberts solitons for a penetrable obstacle. Beyond superfluids of light, our results provide a general framework for the critical speed of two-dimensional binary nonlinear Schrödinger superflows, including Bose-Bose quantum mixtures.
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© The Author(s), under exclusive licence to EDP Sciences, SIF and Springer-Verlag GmbH Germany, part of Springer Nature 2026
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
