Building Quantum Systems with Ytterbium Rydberg Arrays

Abstract

Neutral atoms trapped in optical tweezer arrays have emerged as a promising platform for quantum science. The dynamic reconfigurability of tweezer traps enables a high degree of single atom control and the generation of large-scale defect-free atom arrays in many geometries. Furthermore, the ability to introduce long-range interactions via excitation to Rydberg states, enables the implementation of high-fidelity multi-qubit gates and the study of many-body quantum physics. Prior to the work in this thesis all existing neutral atom tweezer platforms have used alkali atoms, which have a single valence electron. Alkaline-earth atoms (AEA), such as Ytterbium (Yb), have a second valence electron and additional electronic structure, leading to many potential advantages in terms of coherence and control, including ultralong coherence for nuclear spin qubits encoded in a $J=0$ electronic ground state, metastable states for shelving quantum information or metrological applications, and broad and narrow cycling transitions for rapid laser cooling to low temperatures and low-loss fluorescence imaging. Furthermore, the core electron in AEA Rydberg states enables the trapping of Rydberg states via the polarizability of the ion core, allows for high-fidelity Rydberg state detection utilizing the fast autoionization decay of ion core excited states, and leads to strong hyperfine coupling in Rydberg states of fermionic isotopes. In this thesis, we discuss the motivation (Chapter 1) and many technical details (Chapter 2) for building the first Yb optical tweezer experiment. In Chapter 3, we present a technique for high-fidelity imaging (0.9985) of $^{174}$Yb using the narrow $^{1}S_{0}$ $\rightarrow$ $^{3}P_{1}$ transition for simultaneous cooling and imaging in 532 nm magic-wavelength tweezers. In Chapter 4, we discuss novel spectroscopy of $^{174}$Yb Rydberg states, including the $^{3}S_{1}$ series. In Chapter 5, we show the first demonstration of trapped AEA Rydberg states in red-detuned optical tweezers, utilizing the ion core polarizability. In Chapter 6, we propose and demonstrate a novel scheme for controllably turning on and off Rydberg excitations and Rydberg-mediated entanglement, via light shifts induced by a beam near-resonant with a Yb$^{+}$ ion core transition. Finally, we briefly discuss future steps towards implementing quantum gates in $^{171}$Yb ($I=1/2$) nuclear spin qubits (Chapter 7).