Programmable arrays of alkaline earth atoms: qubits, clocks, and the Bose-Hubbard model

In this thesis, I report on the development of a new experimental platform that features capabilities drawn from optical tweezer arrays, quantum gas microscopes, and optical clocks. We demonstrate that we can trap, cool, image, and manipulate the positions of individual strontium atoms in an optical lattice using a colocated set of optical tweezer arrays. These capabilities allow us to assemble ensembles of hundreds of atoms while maintaining access to controls and observables that have a resolution at the level of a single atom, and a single lattice site.

In the direction of quantum metrology, we demonstrate that the above capabilities can be combined with control of a long-lived optical frequency qubit encoded in the electronic states of strontium to realize a new kind of optical clock. This “tweezer array clock” provides access to measurements not typically available in optical clocks while also providing fractional frequency stabilities that are close to the state-of-the-art for synchronous comparisons. We further engineer interactions between optical frequency qubits encoded in different atoms by exciting the atoms to high-lying Rydberg states. We use the resulting interactions to perform entangling gates, and to prepare large entangled states that enable synchronous optical clock measurements with a precision below the standard quantum limit.

In the direction of quantum simulation, we control the motion of atoms in a tunnel-coupled optical lattice to study single- and multi-particle quantum walks. By taking advantage of the ability to modify the local potential in the lattice using optical tweezers, we show that these quantum walks can be used as a resource in various algorithms, including in the first experimental demonstration of spatial search by quantum walk. By further taking advantage of the ability to prepare, evolve, and detect large ensembles of atoms in the lattice with high fidelity, we significantly advance the state-of-the-art in Fock state boson sampling. Applying the above techniques to interacting atoms allows us to introduce a new approach to studying both ground states and dynamics in the Bose-Hubbard model. We present preliminary results involving the dynamics of hard core bosons, as well as the preparation of a superfluid that is assembled a single atom at a time using optical tweezers.

The combination of high fidelity control of arrays of atomic qubits with complicated many body dynamics, and state-of-the-art capabilities in frequency metrology, results in a fruitful blurring of the lines between quantum computation, simulation, and metrology. As the capabilities of these systems continue to expand, we are hopeful that ideas from quantum information science can be drawn on to perform ever more precise measurements and, conversely, that metrological tools and techniques can be used as precision probes of complicated and poorly understood quantum many body effects.