February 10th 2023
Dr. Arka Majumdar will be hosting Assistant Professor Hendrik Utzat from the University of California, Berkeley for a Special Technical Seminar being held Friday, February 10, 2023, at 10:30 a.m. in CHB 102 conference room (University of Washington).
Seminar title: Genuine Quantum Interference of Single-Photons Emitted from Colloidal Lead-Halide Perovskite Quantum Dots
Abstract:
Chemically prepared colloidal semiconductor quantum dots have long been proposed as scalable and color-tunable single emitters in quantum optics, but they have typically suffered from prohibitively incoherent emission. This changed in 2019, when individual lead-halide perovskite quantum dots (PQDs) at low temperatures were shown to display highly efficient single-photon emission with optical coherence approaching the radiative lifetimes.
In this talk, I highlight the latest developments of perovskite quantum emitters, including our first demonstration of two-photon (Hong-Ou-Mandel) interference of sequentially emitted single photons. We achieve visibilities of up to 0.55, above the limit for genuine quantum interference, even without cavity acceleration of the emission, indicating that entangled-photon generation is indeed possible with perovskites. I further present a detailed temperature-dependent single-nanocrystal study of the optical dephasing mechanism in perovskite quantum dots indicating that ligand-engineering can increase the coherent fraction of the emitted photons by reducing inelastic phonon scattering. We show that the residual dephasing of the excited state is caused by thermally activated elastic phonon scattering of low energy (1-3meV) modes.
Our results indeed confirm the potential of perovskite quantum dots as scalable, colloidal sources of coherent, indistinguishable single photons, and that can be optimized by chemical means and integrated with nanophotonic cavities.