Quantum vortices of strongly interacting photons

Vortices are a hallmark of topologically nontrivial dynamics in nonlinear physics and arise in a huge variety of systems, from space and atmosphere to condensed matter and quantum gases. In optics, vortices manifest as phase twists of the electromagnetic field, commonly formed by the interaction of light and matter. Formation of vortices by effective interaction of light with itself requires strong optical nonlinearity and has therefore been confined, until now, to the classical regime. Here we report on the realization of quantum vortices resulting from a strong photon-photon interaction in a quantum nonlinear optical medium. The interaction causes faster phase accumulation for co-propagating photons. Similarly to a plate pushing water, the local phase accumulation produces a quantum vortex-antivortex pair within the two-photon wavefunction. For three photons, the formation of vortex lines and a central vortex ring attests to a genuine three-photon interaction. The wavefunction topology, governed by two- and three-photon bound states, imposes a conditional phase shift of $\pi$-per-photon, a potential resource for deterministic quantum logic operations.Comment: The first two authors contributed equally to this wor

Exploring the Bifunctionality of Co₃S₄/NiS₂/Cu₂S Heterojunction Nanocomposites for Hybrid Supercapacitors and Double Z‑Scheme-Driven Dye Degradation

A trimetallic heterojunction-derived Co3S4/NiS2/Cu2S with different ratios through a two-step hydrothermal method was successfully synthesized, showing multifunctional properties such as excellent electrochemical behavior and high photocatalytic activity. Both electrochemical and photocatalytic performances were optimized by adjusting the concentration of Cu without any change in Co and Ni concentrations. Among the synthesized nanocomposites, CNCS-0.15 (Co3S40.5/NiS20.5/Cu2S0.15) depicted the maximum specific capacity of 464.16 C g–1 at 1 A g–1 as revealed from electrochemical measurements. Further for real-time usage, assembling of a hybrid supercapacitor CNCS-0.15(+)||activated carbon(−) furnished an energy density of 84.95 W h kg–1 at a power density of 1134 W kg–1 with good capacity retention of 93.64% for 5000 cycles. In addition, CNCS-0.15 also displayed remarkable photocatalytic performance under visible light illumination by utilizing Congo red (CR) dye. It could effectively degrade 91% of CR (40 mg L–1) through a double Z-scheme mechanism owing to the charge carriers' availability with higher redox ability. The Mott–Schottky analysis along with the scavenging experiment confirmed the involvement of h+ and O2–. radicals in the photodegradation. Due to highly interconnected nanoflake architectures, CNCS-0.15 holds a promising application as a supercapacitor electrode and visible light active photocatalyst