Abstract:
Resonance fluorescence (RF) of a two-level-emitter (TLE) under weak monochromatic excitation has been known for decades to display simultaneously anti-bunching in the photon number statistics and the driving laser’s linewidth. Anti-bunching implies photons were spontaneously emitted and must therefore possess a bandwidth no less than 1/2πT1, a limit imposed by the TLE’s radiative lifetime T1. A laser-like linewidth violates this limit. To resolve this issue, we develop a novel pure-state description for the joint quantum system of the TLE and its light emission (not the excitation laser) by treating TLE’s interaction with the light field a purely coherent process. We view the resulting RF as a stream of phase-locked lifetime-limited broadband single photons that are entangled in time-energy domain. It is the interference of these broadband photons, rather than two separate scattering mechanisms, that gives rise to the sub-natural linewidth that is superimposed upon the so-called “incoherently scattered light”. Moreover, we derive an explicit dependence of the first-order coherence of the RF on the excitation power, which we successfully verify by experiments using a quantum dot (QD) micropillar device [1]. Furthermore, we report observation of the Mollow triplets under few-photon excitation [2].
[1] X-J Wang et al., “Coherence in resonance fluorescence”, arXiv:2312.13743 (2023).
[2] B Wu et al., “Mollow triplets under few-photon excitation”, Optica 10, 1018 (2023).
Biography:
Zhiliang Yuan received his PhD and post-doctoral training from the Institute of Semiconductors, CAS (1993-1997), and the University of Oxford (1997-2001), respectively. He then spent 20 years at Toshiba Cambridge Laboratory before returning to China in 2021. His notable scientific contributions include the first single-photon light emitting diode, the first 100-km and the first 10Mb/s quantum key distribution (QKD) systems, and the proposal and demonstrations of twin-field QKD. He co-authored 130+ journal papers including 17 in Science, Nature & Nature sub-journals, and more than 60 US/UK/China patents. He was awarded with ChangJiang Chair Scholar (2023), Optica Fellow (2023) and Fellow of the Institute of Physics (2022).
Seminar by the NYU-ECNU Institute of Physics at NYU Shanghai