Simulating errors of a quantum device using variational quantum channels
A hybrid quantum classical (HQC) computer system, which includes both a classical computer component and a quantum computer component, implements indirect benchmarking of a near term quantum device by directly benchmarking a virtual quantum machine that models the quantum computer device and that has a level of errors that corresponds to the level of errors associated with the quantum computer device. The direct benchmarking, conducted using quantum error correction tools, produces a probability distribution of error syndromes that may be used as a probability distribution of error syndromes for the quantum computer device.
1. A method for use with a hybrid quantum-classical device, the hybrid quantum-classical device comprising a quantum device and a classical computer, the classical computer comprising at least one processor and at least one non-transitory computer-readable medium having computer program instructions stored thereon, the computer program instructions being executable by the at least one processor to perform the method, the method comprising:
(A) initializing the quantum device with at least one initial state;
(B) applying a quantum error correcting (QEC) code to the quantum device in the at least one initial state to produce a first output distribution;
(C) sampling the first output distribution;
(D) simulating, on a classical computer, the first output distribution of the quantum device, the simulating comprising:
(D) (1) initializing a simulation of the quantum device on the classical computer with the at least one initial state;
(D) (2) applying the QEC code to the simulation of the quantum device;
(D) (3) applying a simulated variational quantum channel to the simulation of the quantum device to produce a second output distribution;
(E) adjusting parameters of the simulated variational quantum channel to increase the similarity of the first and second output distributions.
2. The method of claim 1 , wherein (E) comprises adjusting parameters of the simulated variational quantum channel to optimally match the first output distribution.
3. The method of claim 1 , wherein the simulated quantum device comprises a simulated programmable quantum computer.
4. The method of claim 1 , wherein the simulated quantum device comprises a simulated quantum annealer.
5. The method of claim 1 , wherein the simulated quantum device comprises a simulated photonic quantum computer, and wherein the QEC comprises a quantum repeater.
6. The method of claim 1 , wherein the quantum device comprises a quantum computer, the quantum computer comprising a plurality of qubits.
7. The method of claim 6 , further comprising using the simulated variational quantum channel to determine improvements to fidelities of two-qubit gates in the quantum computer.
8. The method of claim 1 , wherein the at least one initial state comprises a plurality of initial states.
9. The method of claim 1 , further comprising:
(F) before (B), selecting the QEC code based on error modes of the quantum device.
10. The method of claim 1 , further comprising:
(F) selecting the QEC code based on error modes of the quantum device.
11. A system comprising at least one non-transitory computer-readable medium having computer program instructions stored thereon, the computer program instructions being executable by at least one processor to perform a method, the method comprising:
(A) initializing a quantum device with at least one initial state;
(B) applying a quantum error correcting (QEC) code to the quantum device in the at least one initial state to produce a first output distribution;
(C) sampling the first output distribution;
(D) simulating, on a classical computer, the first output distribution of the quantum device, the simulating comprising:
(D) (1) initializing a simulation of the quantum device on the classical computer with the at least one initial state;
(D) (2) applying the QEC code to the simulation of the quantum device;
(D) (3) applying a simulated variational quantum channel to the simulation of the quantum device to produce a second output distribution;
(E) adjusting parameters of the simulated variational quantum channel to increase the similarity of the first and second output distributions.
12. The system of claim 11 , wherein (E) comprises adjusting parameters of the simulated variational quantum channel to optimally match the first output distribution.
13. The system of claim 11 , wherein the simulated quantum device comprises a simulated programmable quantum computer.
14. The system of claim 11 , wherein the simulated quantum device comprises a simulated quantum annealer.
15. The system of claim 11 , wherein the simulated quantum device comprises a simulated photonic quantum computer, and wherein the QEC comprises a quantum repeater.
16. The system of claim 11 , wherein the quantum device comprises a quantum computer, the quantum computer comprising a plurality of qubits.
17. The system of claim 16 , further comprising using the simulated variational quantum channel to determine improvements to fidelities of two-qubit gates in the quantum computer.
18. The system of claim 11 , wherein the at least one initial state comprises a plurality of initial states.
19. The system of claim 11 , wherein the method further comprises:
(F) before (B), selecting the QEC code based on error modes of the quantum device.
20. The system of claim 11 , wherein the method further comprises:
(F) selecting the QEC code based on error modes of the quantum device.