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Many-Body Cavity Quantum Electrodynamics and Spin Dynamics with an Ensemble of Rare-Earth Ions


Lei, Mi (2024) Many-Body Cavity Quantum Electrodynamics and Spin Dynamics with an Ensemble of Rare-Earth Ions. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/gx1e-en28.


Studying and controlling light-matter and matter-matter interactions is a central theme in quantum physics and provides the foundation for quantum applications. Rare-earth ions (REIs) doped in solids are promising candidates for engineering scalable quantum technologies, such as quantum memories and quantum transducers, and for exploring emerging fundamental phenomena. This is because REIs have highly stable optical and spin transitions at cryogenic temperatures, and as a solid-state platform, they are compatible for integrating with quantum devices using well-established semiconductor manufacturing techniques.

This thesis is centered on nanophotonic devices coupling to an ensemble of REIs. To explore the light-matter interaction, we build a light-matter interface by coupling an inhomogeneously broadened ensemble of ytterbium-171 doped in yttrium orthovanadate to a nanophotonic cavity with high cooperativity. In this many-body cavity quantum electrodynamics (cavity QED) system, we observe the appearance of a narrow transparency window in the cavity reflection spectrum under optical driving (collectively induced transparency, CIT). This phenomenon results from the destructive interference between pairs of two-level emitters across the inhomogeneous line and the saturation of resonant ions. Furthermore, coherent excitation of the system within this transparency window enables us to observe highly nonlinear optical emission, spanning from fast superradiance to slow subradiance. To study matter-matter interactions, we shift the focus to the strongly interacting spins. These spins feature clock transitions and pure spin exchange interactions, leading to comparable magnitudes of interaction strength and on-site disorder. We characterize and control the many-body dynamics via Hamiltonian engineering and population initialization. Furthermore, we observe the emergence of robust subharmonic oscillations under Floquet driving, providing evidence for the presence of a discrete time crystal.

The discoveries in many-body cavity QED enable new mechanisms for achieving slow light and frequency referencing, and they provide potential for superradiant lasers. Meanwhile, our studies on spin dynamics showcase REIs as a promising platform for the study of many-body physics, with potential applications in quantum sensing and quantum simulations. In general, our findings deepen the understanding for a disordered quantum system and offer valuable insights for development of quantum applications.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Rare earth ions; Cavity quantum electrodynamics; Many-body physics;
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Applied Physics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Faraon, Andrei
Group:Institute for Quantum Information and Matter, Kavli Nanoscience Institute
Thesis Committee:
  • Endres, Manuel A. (chair)
  • Faraon, Andrei
  • Painter, Oskar J.
  • Refael, Gil
  • Yao, Norman Y.
Defense Date:14 February 2024
Non-Caltech Author Email:leimichn (AT)
Funding AgencyGrant Number
Co-design Center for Quantum Advantage (C2QA)DE-SC0012704
Army Research Office (ARO)W911NF2010136
Office of Naval Research (ONR)N00014-19-1-2182
Office of Naval Research (ONR)N00014-22-1-2422
Eddleman Graduate FellowshipUNSPECIFIED
Record Number:CaltechTHESIS:04102024-171434556
Persistent URL:
Related URLs:
URLURL TypeDescription adapted for Chapter 2 adapted for Chapter 3 and 4
Lei, Mi0009-0001-5484-7982
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:16347
Deposited By: Mi Lei
Deposited On:16 Apr 2024 23:25
Last Modified:29 Apr 2024 18:27

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