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Humboldt-Universität zu Berlin - Mathematisch-Naturwissen­schaft­liche Fakultät - Institut für Physik

Humboldt-Universität zu Berlin | Mathematisch-Naturwissen­schaft­liche Fakultät | Institut für Physik | Kolloquium | Alle Termine | Institutskolloquium: Dr. Tim Schröder (Nachwuchsgruppenleiter, Institut für Physik der HU Berlin)

Institutskolloquium: Dr. Tim Schröder (Nachwuchsgruppenleiter, Institut für Physik der HU Berlin)

Nanophotonic Spin Systems in Diamond and Gallium Arsenide for Quantum Technology
Wann 22.01.2019 von 15:15 bis 17:00 (Europe/Berlin / UTC100) iCal
Wo Lise-Meitner-Haus, Christian-Gerthsen-Hörsaal, Newtonstraße 15, 12489 Berlin

Nanophotonic Spin Systems in Diamond and Gallium Arsenide
for Quantum Technology

Tim Schröder

Group Leader Integrated Quantum Photonics Group

Humboldt-Universität zu Berlin / Ferdinand-Braun-Institut

A central aim of quantum science and technology is the transfer of quantum information to realize fundamentally secure communication and to establish distributed quantum networks—essential prerequisites for a future quantum internet. The long-distance transfer of quantum information is not an easy task and requires so-called quantum repeaters, the quantum analogue to a repeater in classical telecommunication. A quantum repeater could be implemented with entangled quantum memories or, alternatively, with quantum states composed of multiple entangled photons. Both schemes require efficient spin–photon interfaces between quantum memory and photons as well as scalable photonic integration. Promising physical systems towards quantum repeaters are optically active solid-state spin systems. Proof-of-principle experiments have been realized but are still lacking efficiency, compact integration, and scalability—crucial requirements towards making such schemes accessible for real-world applications.

In this talk, I introduce both quantum repeater schemes, and use their distinct advantages and challenges to motivate our work on optically active spin systems in diamond and gallium arsenide nanostructures. I discuss progress in the development and application of cavity- and waveguide-based spin–photon interfaces and their scalable photonic integration. In the first part of the colloquium I focus on diamond photonics with colour centres [1] and introduce our work on nanophotonic–quantum memory systems. I discuss how diamond nanophotonic devices can be fabricated in a scalable way [2], be integrated into photonic architectures [3], facilitate enhanced single photon rates [4], be used for coherent single photon generation [5], and allow for simultaneous control of several quantum memories in a sub-diffraction volume [5]. In the second part of the colloquium, I introduce the concept of photonic cluster states—quantum states composed of multiple entangled photons. I focus on our recent experimental efforts towards their generation with electron spins in In/Ga/As quantum dots and a proof-of-concept single-spin controlled nanophotonic photon switch with record coherence times [6].

References

[1] T. Schröder et al., J. Opt. Soc. Am. B 33, B65 (2016).

[2] S. Mouradian et al., APL 111, 021103 (2017); N. H. Wan et al., Nano Lett. 18, 2787 (2018).

[3] S. L. Mouradian et al., PRX 5, 031009 (2015); R. N. Patel et al., Nature LSA 5, e16032 (2016).

[4] L. Li et al., Nat. Commun. 6, 6173 (2015); T. Schröder et al., Opt. Mater. Express 7, 1514 (2017).

[5] T. Schröder et al., Nat. Commun. 8, 15376 (2017); E. Bersin et al. ArXiv:1805.06884 (2018).

[6] A. Javadi et al., Nat. Nanotechnol. 13, 398 (2018); D. Ding et al., ArXiv1810.06103 (2018).