Noise suppression in superconducting qubits through on-demand cavity cooling and optimal control

Noise suppression techniques that extend qubit lifetimes, such as reservoir engineering and optimal control, are crucial ingredients for NISQ-era superconducting quantum devices. While control techniques such as dynamical decoupling have been widely adopted in compiling circuits to run quantum algorithms, so far, few experimental studies have co-designed a qubit's control pulses with its dissipative environment. We design a transmon qubit with an effective tunable environment by coupling its readout resonator to an auxiliary lossy mode. We experimentally test that we can effectively remove spurious excitation from the qubit's environment on-demand through a parametrically driven coupling. Furthermore, we study the qubit noise characteristics and explore optimal control strategies for suppressing the engineered, tunable bath. We anticipate that this work will provide insights into noise suppression in superconducting qubits both on the hardware and software levels.