Hannover 2020 – scientific programme
The DPG Spring Meeting in Hannover had to be cancelled! Read more ...
Parts | Days | Selection | Search | Updates | Downloads | Help
Q: Fachverband Quantenoptik und Photonik
Q 58: Quantum gases (Bosons) V
Q 58.4: Talk
Friday, March 13, 2020, 12:00–12:15, e214
Continuous feedback on a quantum gas coupled to an optical cavity — •Rodrigo Rosa-Medina, Katrin Kroeger, Nishant Dogra, Marcin Paluch, Fabian Finger, Francesco Ferri, Tobias Donner, and Tilman Esslinger — Institute for Quantum Electronics, ETH Zurich, 8093 Zurich, Switzerland
Ultracold atoms constitute a highly versatile platform to study quantum many-body dynamics and phase transitions. In our experiment, we realize a driven-dissipative Dicke model by coupling a 87Rb Bose-Einstein condensate (BEC) to a high-finesse optical cavity. The BEC is transversally pumped by a standing wave laser and photons are off-resonantly scattered into the cavity. Above a critical pump power, the system undergoes a phase transition into a superradiant state characterized by a self-organized modulation of the atomic density. Photons leaking out from the cavity provide natural channel for real-time, weak measurements of the system’s state.
We present the experimental realization of an active feedback scheme within the self-organized phase. By acting on the intensity of the pump field, we stabilize the mean intra-cavity photon number (nph). Our micro-controller based feedback architecture can sustain a wide range of constant photon numbers both deep inside the self-organized state (nph > 20) and close to the phase transition (nph < 0.2) for up to 4 seconds. Thereby, we can approach the phase transition with a high degree of control. Our experiments pave the way towards the realization of exotic many-body phases through tailored feedback schemes, such as limit cycles driven by delayed feedback or Floquet time crystals.