Seminarium Fizyki Ciała Stałego

An optimal single-photon source fulfils the following triple benchmark: (I) Brightness: it delivers a single-photon Fock state deterministically “at the push of a button” (and never vacuum cid:clip_image002.png); (II) Purity: it always generates a photon number Fock state cid:clip_image004.png (and never multi-photon Fock states cid:clip_image006.png); (III) Indistinguishability: all the emitted single-photon Fock states are identical, and thus, they perfectly interfere as bosons (displaying the Hong-Ou-Mandel effect). In the first part of this talk, I will discuss the state-of-the-art on near-optimal single-photon emitters [1], based on semiconductor quantum dots in cavities. In this context, I will discuss my recent results on this platform to generate other kinds of quantum states of light beyond single-photon Fock states, such as superposition and scalable multipartite time-entanglement in the photon number basis [2,3].In the second part of this talk, I will discuss another platform to generate single-photons based on atomically thin WSe2 monolayers. The local strain in these monolayers produces a potential capable to trap single excitons and so produce single-photon emission [4]. These quantum dots can be coupled to optical cavities, enhancing their performance towards competitive single-photon sources. First quantum communication testbed-applications with atomically thin WSe2 quantum dots are being implemented [5], promising a “bright future” for these novel emitters. References[1] N. Tomm et al., A Bright and Fast Source of Coherent Single Photons, Nat. Nanotechnol. 16, 399 (2021).[2] J. C. Loredo et al., Generation of Non-Classical Light in a Photon-Number Superposition, Nat. Photonics 13, 803 (2019).[3] S. C. Wein et al., Photon-Number Entanglement Generated by Sequential Excitation of a Two-Level Atom, Nat. Photon. 16, 5 (2022).[4] O. Iff et al., Strain-Tunable Single Photon Sources in WSe 2 Monolayers, Nano Lett. 19, 6931 (2019).[5] T. Gao, M. v Helversen, C. Anton-Solanas, C. Schneider, and T. Heindel, Atomically-Thin Single-Photon Sources for Quantum Communication, ArXiv:2204.06427 [Cond-Mat, Physics:Quant-Ph] (2022).