Capacitively-shunted asymmetric dc-squid for qubit readout and reset

A method comprising:

• forming a tunable resonator by shunting a set of asymmetric DC-SQUIDs with a capacitive device, the tunable resonator configured to read a quantum state of a qubit, an asymmetric DC-SQUID in the set of asymmetric DC-SQUIDs comprising a first Josephson junction and a second Josephson junction, wherein a first critical current of the first Josephson junction is different from a second critical current of the second Josephson junction;
• and
• actively resetting the qubit by applying an external magnetic flux of a first value to the tunable resonator, wherein a first value of the external magnetic flux causes the tunable resonator to tune to a first frequency.

A superconducting fabrication system which when operated to fabricate a tunable resonator device performing operations comprising:

• forming the tunable resonator by shunting a set of asymmetric DC-SQUIDs with a capacitive device, the tunable resonator configured to read a quantum state of a qubit, an asymmetric DC-SQUID in the set of asymmetric DC-SQUIDs comprising a first Josephson junction and a second Josephson junction, wherein a first critical current of the first Josephson junction is different from a second critical current of the second Josephson junction;
• and
• actively resetting the qubit by applying an external magnetic flux of a first value to the tunable resonator, wherein a first value of the external magnetic flux causes the tunable resonator to tune to a first frequency.