Exploring Novel Quantum Physics Using Ytterbium-171 in An Optical Cavity

In this thesis, I present the development of a cavity quantum electrodynamics (CQED) system using single or multiple ensembles of ytterbium-171 atoms and its use for quantum metrology and quantum information science investigations. We develop and study a unified theoretical framework that describes CQED spin systems. We unify the two major roles of cavity light: the measurement of the atomic state and the catalyst for generating entanglement. The obtained model agrees well with the experimental results. We utilize this framework to implement and optimize a variety of quantum metrological applications. With optimized parameters guided by the theoretical model, we achieve a near-unitary spin squeezing in the ground state manifold of ytterbium atoms. We observe a metrological gain of 6.5(4)dB, while the inferred metrological gain without measurement limitation can reach 13dB. In a second experiment, we coherently transfer the entanglement from the ground state manifold to the optical clock transition for its 105 times faster phase accumulation and higher relative accuracy compared with an rf-clock. We infer a 4.4dB of improvement in performance, which is the first demonstration of the quantum entanglement-assisted optical clock operation. We also implement a time-reversal-based quantum metrology protocol. We demonstrate that this method benefits practical quantum metrology since it improves the signal-to-noise ratio by amplifying the signal rather than reducing the noise. Notably, it is insensitive to the measurement noise, the dominant limitation in previous experiments. With the time-reversal protocol, we observed a 12.8(9)dB metrological gain and a record high 11.8(5)dB gain of phase sensitivity. We further bring it to quantum information science. We explore the out-of-time-ordered correlators (OTOCs), a benchmark of how fast the quantum information “scrambles” into the whole quantum many-body system. We demonstrate that the time-reversal method can efficiently use the quantum scrambler’s exponentially fast dynamics as a way to improve the signal. Altogether, we have built and upgraded the machine of this lab to be able to per- form complicated quantum experiments. We can coherently and uniformly prepare and initialize the atomic states, and use the cavity to generate quantum entanglement or undo it among the atomic ensemble. We not only improve the attainable performance of precision measurement but also extend the investigation of quantum metrology to the field of quantum information science.

Name thesis:degree_name

Doctoral

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Physics

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2023

Author dc:creator

• Li, Zeyang

Advisor dc:contributor.advisor

• Vuletic, Vladan

Statement dc:rights

• In Copyright - Educational Use Permitted
• Copyright retained by author(s)

Licence dc:rights.uri

• https://rightsstatements.org/page/InC-EDU/1.0/

Handle dc:identifier.uri

https://hdl.handle.net/1721.1/152556

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/152556