Fast Readout and Reset of a Superconducting Qubit Coupled to a Resonator with an Intrinsic Purcell Filter

Quantum information processing requires qubits that can retain their energy for a long time, and one also needs to be able to rapidly manipulate and measure the qubits. The authors utilize the spatial extent of a microwave resonator to meet both of these requirements. They protect a superconducting qubit from energy decay by simply shifting the position of the coupling port in a conventional device. This study demonstrates a simple technique that enables fast readout and reset of a superconducting qubit without compromising its lifetime. The technique could immediately be incorporated into the design of a superconducting quantum computer.