Constructing and programming quantum hardware for quantum annealing processes

1. An apparatus comprising:

a first pair of logical superconducting units for use in computation, each logical superconducting unit being configured to have quantum states that can be spanned over Pauli operator σ sj i , where i=x, y, or z;

a first pair of control superconducting units for use in assisting the computation without being a computational unit, each control superconducting unit being configured to have quantum states that can be spanned over Pauli operator σ ck i , where i=x, y, or z;

a first coupler between a first logical superconducting unit and a second logical superconducting unit, wherein when a magnetic field is applied along a z direction, the first coupler couples a quantum operator σ s1 z of the first logical superconducting unit with a quantum operator σ s2 z of the second logical superconducting unit in a first coupling represented by σ s1 z σ s2 z ;

a second coupler between a first control logical superconducting unit and a control second superconducting unit, wherein when a magnetic field is applied along a z direction, the second coupler couples a quantum operator σ c1 z of the first control superconducting unit with a quantum operator σ c2 z of the second control superconducting unit in a second coupling represented by σ c1 z σ c2 z ;

a third coupler between the first logical superconducting unit and the second control superconducting unit, wherein when the magnetic field along the z direction is applied, the third coupler couples a quantum operator σ s1 z of the first superconducting unit with a quantum operator σ c2 z of the second superconducting unit in a third coupling represented by σ s1 x σ c2 z ; and

a fourth coupler between the second logical superconducting unit and the first control superconducting unit, wherein when the magnetic field along the z direction is applied, the fourth coupler couples a quantum operator σ s2 z of the first superconducting unit with a quantum operator σ c1 z of the second superconducting unit in a fourth coupling represented by σ s2 x σ c1 z .

2. The apparatus of claim 1 , wherein the first and second logical superconducting units and first and second control superconducting units comprise superconducting qubits having binary quantum states.

3. The apparatus of claim 2 , wherein each superconducting qubit is constructed with a Josephson junction and a capacitor connected in parallel.

4. The apparatus of claim 3 , wherein the logical superconducting units are constructed to have the same precision as the control superconducting units.

5. The apparatus of claim 3 , wherein the control superconducting units are constructed to have less precision than the logical superconducting units.

6. The apparatus of claim 2 , wherein the superconducting qubits of the logical superconducting units are constructed with a Josephson junction and a capacitor connected in parallel, and wherein the superconducting qubits of the control superconducting units are constructed with multi junction Josephson boxes, inductors, and capacitors in parallel and/or series to construct desirable N-level controllable control systems.

7. The apparatus of claim 1 , wherein the first coupler, the second coupler, and the third coupler comprise inductive couplers.

8. The apparatus of claim 1 , comprising multiple pairs of logical superconducting units and multiple pairs of control superconducting units, each pair of logical superconducting units comprising the first and second logical superconducting units coupled through the first coupler, and different pairs of logical superconducting units being coupled through additional couplers, each pair of control superconducting units comprising the first and second control superconducting units coupled through the second coupler, and different pairs of control superconducting units are coupled through additional couplers, and each pair of logical superconducting units being coupled with all pairs of control superconducting units through couplers including the third coupler.

9. The apparatus of claim 8 , wherein the superconducting units and the couplers are configured such that a quantum Hamiltonian characterizing the superconducting units and the couplers is:

H

tot

=

I

⁡

(

t

)

⁢

∑

i

N

⁢

⁢

σ

i

x

+

G

⁡

(

t

)

⁢

(

∑

i

=

1

N

G

⁢

⁢

h

i

G

⁢

σ

i

z

+

∑

i

,

j

=

1

N

G

⁢

⁢

J

ij

G

⁢

σ

i

z

⁢

σ

j

z

+

∑

i

=

1

N

G

⁢

⁢

∑

j

=

1

N

A

⁢

⁢

J

ij

GA

⁢

σ

i

z

⁢

σ

j

z

)

+

P

⁡

(

t

)

⁢

(

-

∑

i

N

⁢

⁢

h

i

⁢

σ

i

z

+

∑

ij

N

⁢

⁢

J

ij

⁢

σ

i

z

⁢

σ

j

z

)

where i represents the i th pair of superconducting unit, h i and J ij have real values that are associated with coupling strength between the first and second superconducting units, I(t), G(t), and P(t) are time-dependent control parameters.