Controlling the Effective Hamiltonian of a Driven Quantum Superconducting Circuit

The thesis illustrates, with a remarkable combination of theoretical analysis and experimental investigation, how the static Hamiltonian of an oscillator with both 3rd and 4th order non-linearity can morph into a profoundly different Hamiltonian under the influence of an oscillating driving force. In a classical system, such transformation would not be considered a novelty, but the author demonstrates that the new Hamiltonian can possess an exotic symmetry with surprising new quantum properties that one would never anticipate from the original Hamiltonian, with no classical equivalent. The root cause of these unexpected properties is a subtle interference effect, which is only possible in a quantum context. Carefully crafted control experiments ensure that measured data are compared with theoretical predictions with no adjustable parameters. Instrumental in this comparison is a new diagrammatic theory developed by the author.