IQIM Postdoctoral and Graduate Student Seminar

Abstract: Vortices appear in optics as phase twists in the electromagnetic field resulting from light-matter interactions. Quantum vortices, characterized by phase singularities in the wavefunction, are typically associated with strongly interacting many-particle systems. However, the emergence of vortices through the effective interaction of light with itself, a phenomenon requiring strong optical nonlinearity, was previously limited to the classical regime until recent advancements.

We recently observed quantum vortices of photons that result from a strong photon-photon interaction in a quantum nonlinear optical medium. The interaction causes faster phase accumulation for copropagating photons, producing a quantum vortex-antivortex pair within the two-photon wave function¹.

Further, we show that the evolution of the n-photon wavefunction is governed by a multiband, Dirac-like dispersion with one massive mode and n − 1-degenerate modes. For three photons, the band dispersion breaks the symmetry between the situations of a photon pair propagating ahead or behind a single photon. We experimentally confirm these findings by measuring the three-photon phase and intensity correlation functions. We observed the effect of trigonal warping on the quantum vortex-ring generated by the three-photon interaction².

For counter propagating photons a non-trivial vortex structure is observed. In intensity correlations structure like higher order bound states starts to appear opposed to the co-propagating photons. For the dissipative interaction the counter propagating photons we observed longest anti-correlation time³.

1. L. Drori∗, B. C. Das∗, T. D. Zohar, G. Winer, E. Poem, A. Poddubny, and O. Firstenberg. Quantum vortices of strongly interacting photons. Science, 381(6654):193–198, 2023.
2. B. C. Das, D. Kiselov, L. Drori, A Nakav, A. Poddubny, and O. Firstenberg. Multiband dispersion and warped vortices of strongly interacting photons, arXiv:2502.11553.
3. 3. B. C. Das*, A. Harkavi*, A. Prakash*, A Nakav, L. Drori, and O. Firstenberg. Quantum nonlinear optics with counter-propagating photons, arXiv:2506.01124 (2025).