Tunable transmon circuit assembly

A method for constructing a tunable transmon qubit, the method comprising:

• fabricating a transmon qubit comprising a first Josephson junction on a first path between a transmission line and a circuit ground, second and third Josephson junctions arranged in parallel with one another on a second path between the transmission line and the circuit ground to form a direct current superconducting quantum interference device (DC SQUID) in parallel with the first Josephson junction, and a capacitor in parallel with first Josephson junction and the DC SQUID on a third path between the transmission line and the circuit ground as to form, in combination with the first path, an outer loop of the transmon qubit;
• determining a frequency curve of the transmon qubit;
• and
• providing a constant bias flux to one of the DC SQUID and the outer loop of the transmon qubit to adjust a frequency curve of the transmon qubit, the frequency curve representing a frequency of a first energy level transition as a function of a control flux.

A tunable transmon qubit comprising:

• a first Josephson junction on a first path between a transmission line and a circuit ground;
• second and third Josephson junctions arranged in parallel with one another on a second path between the transmission line and the circuit ground to form a direct current superconducting quantum interference device (DC SQUID), the DC SQUID being in parallel with the first Josephson junction;
• a capacitor in parallel with the first Josephson junction and the DC SQUID on a third path between the transmission line and the circuit ground as to form, in combination with the first path, an outer loop of the tunable transmon qubit;
• and
• a bias circuit configured to provide a first constant bias flux the DC SQUID and a second constant bias flux to the outer loop of the tunable transmon qubit.