Luka Školč: Superradiant Charge Density Waves: From Solid-State Engineering to Cross-Platform Transport

Long-ranged light–matter interactions in optical cavities can drive collective ordering phenomena such as superradiant self-organization in ultracold atomic gases. Extending these ideas to solid-state electron systems could enable continuous-wave optical control of electronic order but is impeded by the mismatch between optical wavelengths and electronic length scales. Here, we propose a platform for realizing superradiant charge density waves (sCDWs) in doped, driven transition-metal dichalcogenides coupled to an optical cavity. A nanoscale grating generates electric fields at large in-plane optical momenta, allowing cavity photons to couple efficiently to electronic density fluctuations through exciton–polaron processes. We show that tuning the grating periodicity to match intrinsic electronic density fluctuations substantially lowers the threshold pump intensity for superradiance. Furthermore, we analyze the transport properties of the sCDW which could be measured either in solid-state or cold-atom setups. By using Langevin equations of motion, we find that the sCDW is pinned by the cavity light field up to a critical driving strength. For stronger drives, it starts sliding along the applied field with a nontrivial cavity-induced drag force. The all-to-all, cavity-mediated interaction dramatically distinguishes the transport properties of a sCDW from the usual intrinsic charge density waves which form disorder-induced domains.