Single-Photon Quantum Technology with Quantum Dots

Semiconductor quantum dots have improved their optical performance dramatically in recent years, and today a clear pathway is laid out for constructing a deterministic and coherent photon-emitter interface by embedding quantum dots in photonic nanostructures [1]. Such an interface can be employed as an on- demand single-photon source for quantum-information applications, but more generally enables single-photon nonlinearities and deterministic quantum gates. We will review the recent experimental progress on quantum dots coupled to nanophotonic waveguides and cavities enabling unique ways of engineering light-matter interaction. A single-photon coupling efficiency exceeding 98.4% is reported [2] and the coherence of the emitted photons is extracted. Furthermore, various out-coupling strategies for efficiently transferring single photons to an optical fiber are implemented [3]. Currently, the first commercial products based on this technology are being brought to the market [4]. Finally, the unique engineering potential of the nanophotonic waveguides is demonstrated by implementing a chiral quantum interface [5,6]. The prospects and applications of single-photon nonlinearities [7,8] and architectures for scalable quantum networks are discussed [9]

[1] Lodahl et al., Rev. Mod. Phys. 87, 347 (2015).
[2] Arcari et al., Phys. Rev. Lett. 113, 093603 (2014).
[3] Daveau et al., Optica 4, 178 (2017).
[4] Single-photon chip technology is currently commercialized by the company Sparrow Quantum A/S, www.sparrowquantum.com
[5] Söllner et al., Nature Nano. 10, 775 (2015).
[6] Lodahl et al., Nature 541, 473 (2017).
[7] Javadi et al., Nature Comm. 6, 8655 (2015).
[8] Ralph et al., Phys. Rev. Lett. 114, 173603 (2015).
[9] Mahmoodian et al., Phys. Rev. Lett. 117, 24501 (2016)