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Abstract
A central challenge of contemporary physics is understanding strongly correlated quantum matter at the microscopic level, with important applications in materials, medicine, and infrastructure. Particle-level dynamics and correlations are often inaccessible to conventional condensed matter experiments dealing with real solid-state materials, and simulating these systems on classical computers rapidly becomes intractable because of the large space of variables involved. Inspired by Feynman, one way to approach this problem is to recreate the physics of interest in pristine quantum simulators.
In recent years, microwave photons in superconducting circuits have proven to be a rich testbed for modeling many-body phenomena. This platform boasts excellent single-particle and single-site control, site-resolved readout, long quantum state lifetimes compared to the timescale of dynamics, flexible geometries, and prospects for engineered cooling, opening up a variety of avenues to showcase new techniques for gaining physical intuition about manybody physics.
In this thesis, we use superconducting quantum circuits to construct and probe strongly interacting quantum fluids in a 1D Bose-Hubbard circuit. We deterministically prepare fluid eigenstates of our system using particle-by-particle assembly and adiabatic control of lattice site detuning. Site-resolved readout allows us to characterize these multi-particle fluids and probe particle entanglement and correlations. This state preparation technique is reversible; combining it with a manybody Ramsey experiment, we prepare cat states of quantum fluids, and then localize the information about energy differences of these highly entangled and delocalized states into one qubit for measurement. With this single qubit measurement, we then extract information about the manybody eigenstates, the associated excitation spectrum, and thermodynamic observables, a compelling example of how control and measurement overhead need not scale with system size. This work demonstrates broadly applicable new methods of manybody state preparation and characterization in analog quantum simulators.