1. A readout system configured to read a quantum state of a qubit, the readout system comprising: an input stage on which a read pulse is provided; an output stage; and a comparator circuit coupled to the qubit and comprising a first Josephson junction and a second Josephson junction, the comparator circuit being configured to provide an output pulse on the output stage in response to the read pulse to indicate a first quantum state of the qubit based on a bias current flowing through the first and second Josephson junctions in a first direction, and to not provide the output pulse on the output stage in response to the read pulse to indicate a second quantum state of the qubit based on the bias current flowing through the first and second Josephson junctions in a second direction.