Twisting, Binding, and Probing Matter Waves in a Rubidium Cavity QED System

Luo, Chengyi

Graduate Thesis Or Dissertation

Twisting, Binding, and Probing Matter Waves in a Rubidium Cavity QED System Public Deposited

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Citeable URL: https://scholar.colorado.edu/concern/graduate_thesis_or_dissertations/m326m339s

Abstract

In this thesis work, I have explored a novel platform for quantum metrology and many-body physics by realizing matter-wave interferometric controls in a high finesse cavity. By correlating the internal states of the atoms to the external degrees of freedom, we demonstrated direct entanglement generation on the momentum states of the atoms with two distinct approaches, quantum non-demolition measurement and one-axis twisting dynamics. After injecting the squeezed momentum states into a matter-wave interferometer, we realized an entanglement-enhanced matter-wave interferometer for the first time.

Decoupling the momentum states from the internal states with all atoms in the same atomic spin state, we realized a novel cavity-mediated collective momentum-exchange interaction in which pairs of atoms swap their momenta by exchanging photons through the cavity. The momentum-exchange interaction leads to an observed all-to-all Ising-like interaction in a matter-wave interferometer, which is useful for entanglement generation. A many-body energy gap also emerges, effectively binding interferometer matter-wave packets together to suppress Doppler dephasing with analogies to Mössbauer spectroscopy. In the same system, by adding new laser frequency control for driving pair creation/annihilation processes, we realized Hamiltonian engineering of collective XYZ spin models between two momentum states and the first demonstration of the long-sought two-axis counter-twisting dynamics.

The entanglement-enhanced matter-wave interferometer experiment shed new light on improving future atom interferometers by reducing the fundamental quantum source of imprecision. The momentum-exchange interaction provides new options for interacting momentum states enabled by the cavity. The Hamiltonian engineering realized here not only enables new dynamics for entanglement generation but also offers new possibilities for quantum simulation with atomic momentum states. All these opportunities arise from coupling the atoms to a high-finesse cavity, known as cavity quantum electrodynamics systems. Combining the matter-wave interferometric control and cavity QED, our system provides a new platform for the study of quantum metrology, quantum simulation and many-body physics with qubits based on atomic momentum states.

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