FPO- Samuel Saskin, "Building Quantum Systems with Ytterbium Rydberg Arrays"

Fri, Oct 15, 2021, 1:00 pm
Chair's Conference Room, 202 Jadwin Hall

Abstract: Neutral atoms trapped in optical tweezer arrays have emerged as a promising platform for quantum simulation and quantum computation. The dynamic reconfigurability of optical tweezer traps enables a high degree of single atom control and the ability to generate 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 quantum gates and the study of complex 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 and a similar electronic structure to Hydrogen.

Alkaline-earth atoms (AEA), such as Ytterbium (Yb) and Strontium (Sr), which have a second valence electron, have additional electronic structure that leads 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 existence of a 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 effective hyperfine coupling in the Rydberg states of fermionic AEA isotopes.

In this thesis we discuss the motivation (Chapter 1) and many of the technical details (Chapter 2) towards building the first Yb optical tweezer experiment. In Chapter 3, we present on a technique for high-fidelity imaging (0.9985) of 174Yb using the narrow 1S0 → 3P1 transition for simultaneous cooling and imaging in 532 nm magic-wavelength optical tweezers. In Chapter 4, we discuss novel spectroscopy of 174Yb Rydberg states, including the important 3S1 Rydberg series. In Chapter 5, we show the first demonstration of trapped AEA Rydberg states in conventional red-detuned optical tweezers, utilizing the polarizability of the ion core. 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, in Chapter 7, we briefly discuss future steps towards implementing single and multi-qubit gates in 171Yb (I = 1/2) nuclear spin qubits.