March 13
@
1:00 PM
–
2:00 PM
2540 Engineering Hall
Optical relaxation dynamics of nanocavity-coupled erbium ensembles
Abstract: Tailoring the interaction between optical emitters and their electromagnetic environment is of both fundamental scientific interest and practical relevance for applications such as quantum communication and quantum information processing. By tuning the photonic density of states, one can drastically modify the emission properties of these emitters, a phenomenon that underpins the thriving research area of cavity quantum electrodynamics. In this talk, we will first present our rare earth doped nanocavity platform that is being pursued for future quantum optical memory devices operating at cryogenic temperatures. Our spin qubit system consists of Er 3+ ions with a natural optical transition in the telecom (~1520 nm), but the long optical lifetime of these ions (order of milliseconds) necessitates the use of an optical cavity to greatly enhance the emission rate. More specifically, we grow thin film Er 3+ -doped titanium dioxide (TiO 2 ) atop silicon-on-insulator wafers and fabricate small mode volume photonic crystal cavities via etching through both the TiO 2 and Si device layers. We have thus far demonstrated that when the optical cavity is resonant with optical transition of the Er 3+ ions, the optical lifetime can show an enhancement (Purcell factor) up to several hundred [1]. However, in addition to quantum communication applications, we can use the long optical lifetimes of rare-earth ions for more fundamental optical decay modification experiments [2]. For our system, the ensemble of Er 3+ emitters that couples to the cavity exhibit a much broader inhomogeneous linewidth than the cavity. When the optical cavity is tuned through the Er 3+ inhomogeneous distribution, the resultant Purcell factor exhibits an anomalous slowing of the decay when the cavity is resonant with the center of the distribution. We will examine the experimental Purcell factor dependence on resonant laser pump power, as well as the spectral dependence of the PLE emission. We will discuss our attempts to capture qualitative aspects of this decay rate suppression using a semi-classical model of non-interacting emitters mediated by a common cavity. Finally, we will discuss a recent material synthesis development to make our Er 3+ :TiO 2 system potentially more scalable for foundry- level deployment [3].
Dr. Alan Dibos
Presenter Bio: Dr. Dibos is an expert in nanofabrication and cryogenic measurement of low-dimensional optical nanostructures. His research interests include optical coupling of photonic and plasmonic nanocavities to atom-like defect centers in solid-state hosts. The goal is to modify the spectral properties, increase photon emission rates, and improve the photon collection efficiency for quantum information science applications. To that end, Dr. Dibos works as a principal investigator (PI) in Q-NEXT investigating telecom quantum memories based upon solid-state spins at low temperatures and as a member of the InterQnet project at Argonne exploring heterogeneous quantum network integration. Dr. Dibos is also lead-PI on a LDRD project involving incorporation of on-chip superconducting nanowire single photon detectors (SNSPDs) to increase device functionality.
Education
PhD, Applied Physics, Harvard Univ. (2015)
BS, Physics, Univ. of Kansas, (2006)
Professional Experience
Assistant Scientist, Q-NEXT, Argonne National Lab: 2024 – Present
Assistant Scientist, Center for Nanoscale Materials, Argonne National Lab: 2019 – 2024
Postdoctoral Scholar, Electrical Engineering, Princeton: 2016 – 2019
Postdoctoral Scholar, Chemistry, Harvard: 2015 – 2016
Research Assistant, Applied Physics, Harvard: 2006 –2015
[1] A. M. Dibos et al., “Purcell enhancement of erbium ions in TiO 2 on silicon nanocavities,” Nano Lett. 22,
6530 (2022).
[2] M. T. Solomon et al. “Anomalous Purcell decay of strongly driven inhomogeneous emitters coupled to
a cavity.” arXiv, DOI: 10.48550/arXiv.2309.16641 (2023).
[3] C. Ji et al. “Nanocavity-mediated Purcell enhancement of Er in TiO 2 thin films grown via atomic layer
deposition.” arXiv, DOI: 10.48550/arXiv.2309.13490 (2023). Accepted in ACS Nano.