Physical realizations of a universal adiabatic quantum computer
Devices, methods and articles advantageously allow communications between qubits to provide an architecture for universal adiabatic quantum computation. The architecture includes a first coupled basis A 1 B 1 and a second coupled basis A 2 B 2 that does not commute with the first basis A 1 B 1 .
1. A system, comprising:
a first superconducting flux qubit comprising a first rf-SQUID, the first rf-SQUID comprising a first superconducting loop interrupted by a first Josephson junction;
a second superconducting flux qubit comprising a second rf-SQUID, the second rf-SQUID comprising a second superconducting qubit loop interrupted by a second Josephson junction, the second superconducting flux qubit capacitively communicatively coupled to the first superconducting flux qubit to provide a transverse coupling between the first and the second superconducting flux qubits via a coupler, wherein the coupler comprises:
a first conductive path between a first side of the first Josephson junction and a first side of the second Josephson junction, the first conductive path interrupted by a first coupling capacitance; and
a second conductive path between a second side of the first Josephson junction and a second side of the second Josephson junction, wherein at least one of the first and the second Josephson junction comprises a compound Josephson junction.
2. The system of claim 1 wherein the first coupling capacitance comprises a discrete capacitor.
3. The system of claim 1 wherein the first coupling capacitance comprises an intrinsic coupler capacitance.
4. The system of claim 1 wherein the first and the second conductive paths are superconducting below a critical temperature to form superconductive paths.
5. The system of claim 1 , further comprising:
a second coupling capacitance coupled in series with the first coupling capacitance;
a circuit comprising a tunable inductance and a tunable capacitance coupled in parallel, the circuit coupling a node between the first and the second coupling capacitances and the second conductive path,
wherein the coupler in operation is selectively tunable by adjusting the impedance of the circuit.
6. The system of claim 5 wherein at least one of the first and the second coupling capacitances comprises an intrinsic coupler capacitance.
7. The system of claim 5 wherein the tunable inductance comprises an adjustable inductor.
8. The system of claim 1 , further comprising:
a second coupling capacitance coupled in series with the first coupling capacitance;
a compound Josephson junction coupling a node between the first and the second coupling capacitances and the second conductive path, the compound Josephson junction comprising:
a third Josephson junction; and
a fourth Josephson junction in parallel with the third Josephson junction,
wherein the coupler in operation is selectively tunable by adjusting a flux threading the compound Josephson junction.
9. A system, comprising:
a first superconducting flux qubit comprising a first rf-SQUID, the first rf-SQUID comprising a first superconducting loop interrupted by a first Josephson junction;
a second superconducting flux qubit comprising a second rf-SQUID, the second rf-SQUID comprising a second superconducting qubit loop interrupted by a second Josephson junction, the second superconducting flux qubit capacitively communicatively coupled to the first superconducting flux qubit to provide a transverse coupling between the first and the second superconducting flux qubits via a coupler, wherein the coupler comprises:
a first conductive path between a first side of the first Josephson junction and a first side of the second Josephson junction, the first conductive path interrupted by a first coupling capacitance; and
a second conductive path between a second side of the first Josephson junction and a second side of the second Josephson junction, the system further comprising:
a second coupling capacitance coupled in series with the first coupling capacitance;
a circuit comprising a tunable inductance and a tunable capacitance coupled in parallel, the circuit coupling a node between the first and the second coupling capacitances and the second conductive path,
wherein the coupler in operation is selectively tunable by adjusting the impedance of the circuit.
10. The system of claim 9 wherein at least one of the first and the second coupling capacitance comprises a discrete capacitor.
11. The system of claim 9 wherein at least one of the first and the second coupling capacitance comprises an intrinsic coupler capacitance.
12. The system of claim 9 wherein the first and the second conductive paths are superconducting below a critical temperature to form superconductive paths.
13. The system of claim 9 wherein the tunable inductance comprises an adjustable inductor.
14. A system, comprising:
a first superconducting flux qubit comprising a first rf-SQUID, the first rf-SQUID comprising a first superconducting loop interrupted by a first Josephson junction;
a second superconducting flux qubit comprising a second rf-SQUID, the second rf-SQUID comprising a second superconducting qubit loop interrupted by a second Josephson junction, the second superconducting flux qubit capacitively communicatively coupled to the first superconducting flux qubit to provide a transverse coupling between the first and the second superconducting flux qubits via a coupler, wherein the coupler comprises:
a first conductive path between a first side of the first Josephson junction and a first side of the second Josephson junction, the first conductive path interrupted by a first coupling capacitance; and
a second conductive path between a second side of the first Josephson junction and a second side of the second Josephson junction, wherein at least one of the first and the second Josephson junction comprises a compound Josephson junction, the system further comprising:
a second coupling capacitance coupled in series with the first coupling capacitance;
a compound Josephson junction coupling a node between the first and the second coupling capacitances and the second conductive path, the compound Josephson junction comprising:
a third Josephson junction; and
a fourth Josephson junction in parallel with the third Josephson junction,
wherein the coupler in operation is selectively tunable by adjusting a flux threading the compound Josephson junction.
15. The system of claim 14 wherein at least one of the first and the second coupling capacitance comprises a discrete capacitor.
16. The system of claim 14 wherein at least one of the first and the second coupling capacitance comprises an intrinsic coupler capacitance.
17. The system of claim 14 wherein the first and the second conductive paths are superconducting below a critical temperature to form superconductive paths.