Freiburg 2024 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 7: Quantum Communication I

Q 7.2: Talk

Monday, March 11, 2024, 11:15–11:30, HS 3219

Vacuum mediated photon pair emission by a single atom — •Tobias Frank, Gianvito Chiarella, Pau Farrera, and Gerhard Rempe — Max Planck Institute for Quantum Optics

Single atoms coupled to high finesse optical cavities serve as a key platfrom for future quantum networks, where photonic qubits must be distributed, stored and processed efficiently. This platform offers scalability, either by increasing the number of simultaneously coupled emitters or cavity modes. The development of optical-fiber based high finesse Fabry-Perot resonators facilitates the coupling of spatially independent resonator modes to the same emitter. Our group previously implemented such a system using single ⁸⁷Rb atoms coupled to two crossed optical fiber cavities in the high cooperativity regime. The versatility of this system enables the implementation of a passively heralded quantum memory [1] and a nondestructive qubit detector [2]. We recently extended the capabilities using three atomic energy levels coupled to the two cavities in a ladder configuration. This configuration generates pairs of single photons which are efficiently coupled into separate optical fibers. Using numerical simulations, we find parameters in the regime of strong coupling, for which our system could generate photon pairs without populating the intermediate atomic state. We explain this process in analogy to STIRAP but mediated by the vacuum field in both cavities.

[1] Brekenfeld, M., Niemietz, D., Christesen, J.D. et al. Nat. Phys. 16, 647-651 (2020) [2] Niemietz, D., Farrera, P., Langenfeld, S. et al. Nat. 591, 570-574 (2021)

Keywords: Cavity QED; Fiber cavities; Photons; Atoms; Double-vacuum STIRAP