Fast multiplexed superconducting qubit readout with intrinsic Purcell filtering

Understand

Fast and accurate qubit measurement remains a critical challenge on the path to fault-tolerant quantum computing.

• In superconducting quantum circuits, fast qubit measurement has been achieved using a dispersively coupled resonator with a large external linewidth.
• This necessitates the use of a Purcell filter that protects the qubit from relaxation through the readout channel.
• Here we show that a readout resonator and filter resonator, coupled to each other both capacitively and inductively, can produce a compact notch-filter circuit that effectively eliminates the Purcell decay channel through destructive interference.