Single-Shot Flow Spectroscopy of a Polariton Condensate: Kibble-Zurek and Kolmogorov-Like Scaling

Quantized vortices are fundamental topological excitations of quantum fluids. We report single-shot interferometric measurements of spontaneous vortex nucleation in a room-temperature organic exciton-polariton condensate. From hundreds of independent realizations we find random vortex-core positions and unbiased circulation, consistent with intrinsically stochastic, unpinned defect formation. The mean vortex number scales with pump power above threshold with an exponent consistent with Kibble-Zurek freeze-out in a driven-dissipative condensate. Using reconstructed phase maps we obtain single-shot flow fields, compute the incompressible component, and extract kinetic-energy spectra. Vortex-containing realizations develop a robust Kolmogorov-like segment with Einc(k) proportional to k^(-5/3) over a finite k range, indicating the onset of turbulent spectral scaling in a quantum fluid of light. These results establish single-shot access to phase and flow as a direct route to quantifying stochastic defect formation and emerging turbulence in polariton condensates.

💡 Research Summary

The authors present a comprehensive study of spontaneous vortex formation and turbulent flow in a room‑temperature organic exciton‑polariton condensate, using a novel single‑shot interferometric technique. An organic BODIPY‑Br microcavity (186 nm active layer, 10‑pair bottom DBR, 8‑pair top DBR) is pumped with 250 fs, 400 nm pulses focused to a ~23 µm spot. For each pump pulse a Mach‑Zehnder off‑axis holography records an interferogram; an off‑axis digital holography algorithm reconstructs the real‑space phase ϕ(r) and intensity I(r). The local wave‑vector field k(r)=∇ϕ(r) provides a full velocity map, which is Helmholtz‑decomposed to isolate the incompressible (vorticity‑carrying) component.

From hundreds of independent realizations the authors identify vortex cores as 2π phase windings (fork dislocations in the interferograms). Vortices appear at random positions, with no preferred nucleation sites, and both clockwise and counter‑clockwise circulations are equally probable (98 vortices, 109 antivortices). In ~98 % of cases the vortex core lies on the interface between two large‑scale counter‑propagating flow domains, indicating that vortices are generated by spontaneous symmetry breaking rather than by static disorder. Repeated shots at the same location show that vortices can appear, disappear, or even reverse circulation, confirming the absence of pinning.

To test the Kibble‑Zurek mechanism (KZM), the mean vortex number ⟨N_V⟩ is plotted versus the effective quench parameter (P–P_thr)/P_thr, where P_thr≈551 µJ cm⁻² is the condensation threshold. In the range 2.75 ≤ (P–P_thr)/P_thr ≤ 4.3 the data follow a power law ⟨N_V⟩∝