Patent attributes
A technique relates to a qubit readout system. A cavity-qubit system has a qubit and a readout resonator and outputs a readout signal. A lossless superconducting circulator is configured to receive the microwave readout signal from the cavity-qubit system and transmit the microwave readout signal according to a rotation. A quantum limited directional amplifier amplifies the readout signal. A directional coupler is connected to and biases the amplifier to set a working point. A microwave bandpass filter transmits in a microwave frequency band by passing the readout signal while blocking electromagnetic radiation outside of the microwave frequency band. A low-loss infrared filter has a distributed Bragg reflector integrated into a transmission line. The low-loss filter is configured to block infrared electromagnetic radiation while passing the microwave readout signal. The low-loss infrared filter is connected to the microwave bandpass filter to receive input of the microwave readout signal.
