报告时间：1月25日 周四 上午10:00
报告人：Dr. Hannes Busche(Joint Quantum Centre Durham-Newcastle)
报告题目： Contactless quantum non-linear optics in cold Rydberg ensembles
Rydberg non-linear optics  has emerged as a viable approach to induce strong effective photon-photon interactions, e.g. for applications in optical quantum information processing. Using electromagnetically induced transparency and photon storage, the μm-ranged dipolar interactions between collective Rydberg excitations, can be mapped onto photons. So far, experiments focussed on observing Rydberg-mediated photon interactions between overlapping modes within a single cold atomic medium . Recently however, we have demonstrated an effective interaction between photons stored in spatially separate atomic ensembles and propagating in non-overlapping modes . By analysing the statistics of the retrieved photons, we observe how the interaction varies while changing the distance between the clouds, the Rydberg state employed for storage, and the interaction time.
The stored photons can be coherently controlled using an additional microwave field which drives transitions between Rydberg states. Interfacing with microwaves allows to drive high-fidelity Rabi oscillations while the photons are stored and to shape the retrieved pulse . The degrees of freedom provided by contactless, long-range effective interactions between stored photons combined with microwave control of their state and phase may lead towards a Rydberg-based all-optical quantum gate  and applications in quantum simulation.
 O. Firstenberg, C. S. Adams, and S. Hofferberth, J. Phys. B, 49, 15 (2016).
 H. Busche, P. Huillery, S. W. Ball, T. Ilieva, M. P. A. Jones, and C. S. Adams, Nat. Phys.,13, 655–658 (2017).
 S. W. Ball et al., in preparation.
 D. Paredes-Barato and C. S. Adams, Phys. Rev. Lett.,112, 040501 (2014).