Groups | Seminars || Courses | Outreach


Seminars will be held in room S-141 in the Physics and Astronomy Department building on Mondays at 4:00 PM, unless noted otherwise. When necessary, virtual seminar Zoom login instructions will be sent out via email.

Fall 2022

September 8, 2022, 4:30 PM

Prof. Klaus D. Jöns,
Institute for Photonic Quantum Systems (PhoQS), Center for Optoelectronics and Photonics Paderborn (CeOPP), and
Department of Physics, Paderborn University

The Quest for the Ideal Quantum Light Source

(Host: Eden Figueroa)

With the advent of the second quantum revolution, striving for real-world applications of quantum technologies, enormous efforts have been made to develop and optimize the necessary building blocks. For photonic quantum technologies, which uses light particles –photons– as quantum information carriers (qubits), one crucial technology are quantum light sources generating these qubits. In recent years, epitaxial semiconductor quantum dots have made substantial progress, bringing us closer to practical quantum light sources for photonic quantum technology applications. In particular, quantum dots exhibit the lowest multi-photon emission probability [1], strongly polarization entangled photon pairs at telecom frequencies [2], and two-photon interference raw visibility close to unity [3]. However, no ideal quantum light source has yet been developed, addressing all prerequisites at once. I will discuss our efforts improving source properties such as purity, brightness, indistinguishability, and on-demand entangled photon pair generation. I will put these achievements in relation to the different excitation methods used: resonant excitation of a quantum mechanical 2-level system and two-photon excitation of a 3-level quantum ladder system [4]. Finally, I will discuss solutions to overcome these fundamental challenges and show our recent efforts to simultaneously achieve high purity and indistinguishability from a quantum dot 3-level quantum ladder system [5].

[1] L. Schweickert et al., Appl. Phys. Lett. 112, 093106 (2018).
[2] K.D. Zeuner at al., ACS Photonics 8, 8, 2337–2344 (2021).
[3] E. Schöll et al., Nano Lett. 19(4), 2404–2410 (2019).
[4] E. Schöll et al., Phys. Rev. Lett. 125, 233605 (2020).
[5] F. Sbresny et al., Phys. Rev. Lett. 128, 093603 (2022).

September 12, 2022


(Host: TBD)