Jülich Quantum Computing Seminar: Quantum-optical characterization of single-photon emission from ZnSe-based nanopillars - Christine Falter, PGI-9 & JARA-Fundamentals of Future Information Technology

Online Talk

The "Jülich Quantum Computing Seminar" will take place every three weeks on Tuesdays at 14:00 CET via video conference and is intended to promote cooperation between the working groups conducting research in the field of quantum computing and quantum information at various institutes at Forschungszentrum Jülich.

Access details:

Zoom Link: https://us02web.zoom.us/j/81314526642?pwd=YTFXVDBnQUxibVlxUnZjbEJwbGpSQT09

Meeting ID: 813 1452 6642
Passcode: 01

Quantum-optical characterization of single-photon emission from ZnSe-based nanopillars

Abstract: 

The realization of secure quantum communication networks requires the development of efficient and scalable sources of single, indistinguishable photons [1]. Promising candidates are solid-state single-photon sources (SPSs) based on excitons bound to isolated impurities, due to their almost atom-like quantum optical properties and their excellent scalability [2]. We recently demonstrated highly efficient and spectrally tunable single photon emission by spatially isolating individual Cl donors in ZnSe/ZnMgSe quantum well (QW) nanopillar (NP) structures covered with a resist mask [3] (Fig. 1).

In my talk, I will show how the three most important features of a good SPS can be experimentally characterized and how our source compares to the state of the art:

1.) The photon extraction efficiency (PEE) quantifies how efficiently single photons are created and coupled out of the SPS. From photoluminescence measurements, the PEE of our SPS is determined to be as high as 16%. Additionally, lifetime measurements indicate a short radiative lifetime of about 200ps, which confirms the high internal efficiency of our source.

2.) To reveal the single photon purity the second-order correlation function is measured using a Hanbury-Brown-Twiss setup. In these measurements clear photon antibunching is observed using pulsed, above band gap excitation and a 𝑔⁽²⁾(𝜏=0)<0.2 is achieved.

3.) Finally, I investigated the degree of indistinguishability between successively emitted photons from the same device using the Hong-Ou-Mandel effect i.e., the fact that identical photons interfering at a beam splitter will bunch in the same output arm. This is possible using an unbalanced free-space Michelson-type interferometer [4]. The first measurement indicates a high degree of indistinguishability of up to 90%. I verified this result using Monte Carlo simulations.

Cl-doped ZnSe/ZnMgSe QW structures show excellent optical properties regarding single photon emission. The high PEE and the remarkable degree of sequential indistinguishability pave the way for these structures to serve as highly efficient SPSs in future quantum communication networks.

References:

[1] J.i Lee et al., AVS Quantum Sci. 2, 031701 (2020), DOI: 10.1116/5.0011316

[2] K. Sanaka et al., Proceedings of SPIE - The International Society for Optical Engineering. 7225. (2009), DOI: 10.1117/12.814136.

[3] Y. Kutovyi et al., ACS Nano, 16 (9) (2022), 14582-14589,DOI: 10.1021/acsnano.2c05045

[4] C. Santori et al., Nature 419.6907 (2002), 594–597, DOI: 10.1038/nature01086.

Additional Information: Christine Falter