Tunable Coupling Between Photon Bose-Einstein Condensates

Carl Wieman

Péter Horák, Helmut Ritsch

Mario Vretenar, Ben Kassenberg, Shivan Bissesar +2 more

Josephson junctions are the basis for many important fields, such as ultrafast electronics with magnetic flux quanta and superconducting quantum computing. The physical predictions of Josephson junctions are highly universal and can be observed in systems as diverse as coupled superconductors, atomic Bose-Einstein condensates, and others. We experimentally demonstrate tunable tunneling between two photon Bose-Einstein condensates by a targeted shaping of the potential landscape acting on the photons during the tunneling process. The investigated device realizes an optical analogue of a 0,π-Josephson junction, which can act as a building block for an ultrafast all-optical spin glass simulator. The potential landscape in our photon Bose-Einstein condensate Josephson junctions is realized by a combination of direct laser writing for permanent mirror nanostructuring, and heating a thermosensitive polymer for runtime fine tuning of couplings.

Ghaisud Din, Muqaddar Abbas, Pei Zhang

We present a theoretical investigation of spin-orbit photonics within a fixed mirror cavity system containing a Bose-Einstein condensate (BEC), in which the Bogoliubov excitation modes of the condensate are treated as effective mechanical oscillators. By embedding the condensate in a single-mode optical cavity, we explore the emergence and modulation of the photonic spin Hall effect (PSHE) through the spin-dependent transverse shifts of a weak probe field. The optical response —encoded in the real and imaginary components of the output field susceptibility— is systematically analyzed as a function of the condensate-cavity coupling strength, revealing a controllable enhancement or suppression of the spin-orbit interaction. Our model captures how the interplay between collective BEC excitations and cavity photon dynamics induces nontrivial modifications in spin-dependent light propagation. Notably, we uncover that the Bogoliubov mode coupling acts as a tunable channel for mediating spin angular momentum transfer within the cavity, offering a novel route for engineering compact, quantum-coherent spin-orbit photonic devices.

Allard P. Mosk

张建军, 袁建辉, 张俊佩 +1 more