Mainz 2017 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 18: Quantum Effects: Cavity QED I

Q 18.7: Talk

Tuesday, March 7, 2017, 12:30–12:45, P 4

Quantum optical circulator controlled by a single chirally coupled atom — Michael Scheucher, Adèle Hilico, •Elisa Will, Jürgen Volz, and Arno Rauschenbeutel — Vienna Center for Quantum Science and Technology, Atominstitut, TU Wien, Austria

Integrated optical circuits for information processing promise to outperform their electronic counterparts in terms of bandwidth and energy consumption. However, such circuits require components that control the flow of light. Here, a particular important class are nonreciprocal devices. Recently, we realized a quantum optical circulator. For this purpose, we strongly couple a ⁸⁵Rb atom to a whispering-gallery-mode resonator - a so-called bottle microresonator [1] - in which photons exhibit a chiral nature: their polarization is inherently linked to their propagation direction [2]. Interfaced by two optical nanofibers, the system forms a 4-port device. The fact that the atom exhibits polarization-dependent transition strengths leads to a direction-dependent atom-photon interaction. As a consequence, we observe a nonreciprocal behaviour, where photons are directed from one fiber-port to the next [3]. We show that the internal quantum state of the atom controls the operation direction of the circulator [3]. This working principle is compatible with preparing the circulator in a coherent superposition of its operational states. It thus may become a key element for routing and processing quantum information in scalable integrated optical circuits.

[1] C. Junge et al., Phys. Rev. Lett. 110, 213604 (2013)

[2] P. Lodahl et al., arXiv:1608.00446v1

[3] M. Scheucher et al., arXiv:1609.02492v1