Geometric frustration in polygons of polariton condensates creating vortices of varying topological charge

Abstract

Vorticity is a key ingredient to a broad variety of fluid phenomena, and its quantised version is considered to be the hallmark of superfluidity. Circulating flows that correspond to vortices of a large topological charge, termed giant vortices, are notoriously difficult to realise and even when externally imprinted, they are unstable, breaking into many vortices of a single charge. In spite of many theoretical proposals on the formation and stabilisation of giant vortices in ultra-cold atomic Bose-Einstein condensates and other superfluid systems, their experimental realisation remains elusive. Polariton condensates stand out from other superfluid systems due to their particularly strong interparticle interactions combined with their non-equilibrium nature, and as such provide an alternative testbed for the study of vortices. Here, we non-resonantly excite an odd number of polariton condensates at the vertices of a regular polygon and we observe the formation of a stable discrete vortex state with a large topological charge as a consequence of antibonding frustration between nearest neighbouring condensates.

Quantum vortex formation in the “rotating bucket” experiment with polariton condensates

“…Exciton-polariton condensates (7), appearing in the strong lightmatter coupling regime in semiconductor microcavities (8), lie at the interface between noninteracting optical systems and interacting quantum fluids. They can form superfluid currents at elevated temperatures (9)(10)(11) and quantum vortices (12)(13)(14)(15)(16)(17)(18) and, because of their strong nonequilibrium nature, populate geometric vortex states based on the balance of pump-induced gain and dissipation in confining potentials (19)(20)(21)(22)(23)(24)(25)(26). The salient features of exciton-polaritons (hereafter polaritons) are the extremely small effective mass due to the photon part and large nonlinearities due to their excitonic component.…”

Chaos onset in large rings of Bose-Einstein condensates

“…17 ). Recently, a substantial progress in the creation of stable superflows has been achieved in six-and seven-site rings of polaritonic condensates confined in microcavities 18 . Particularly interesting is that persistent circular currents with large winding numbers have been observed for nominally unstable initial configurations for N s = 7 and winding numbers k = 2 and k = 3.…”

“…Particularly interesting is that persistent circular currents with large winding numbers have been observed for nominally unstable initial configurations for N s = 7 and winding numbers k = 2 and k = 3. 18 Motivated by these developments and open questions, we investigate the effect of chaos on circular currents in detail, i.e. dependence on interaction, initial conditions and system size.…”

Spontaneous Formation of Time-Periodic Vortex Cluster in Nonlinear Fluids of Light

“…Exciton-polaritons (from here on polaritons) are composite bosons appearing in the strongcoupling regime in semiconductor microcavities that can undergo a power-driven phase transition into a macroscopic coherent state known as a polariton condensate [23]. Their strong interactions and small effective mass (∼ 10 −5 free electron mass) makes them an exciting testbed to study superfluidity [24][25][26][27] and vorticity [28][29][30][31][32][33][34][35][36] far from equilibrium. Moreover, the two-component σ ± pseudospin structure of polaritons opens pathways to investigate polarization sensitive vorticity [37,38], vector beams and optical skyrmionic textures [31,39] in the strong-coupling regime.…”