Analog processor comprising quantum devices
View Patent ↗Methods and systems for solving various computational problems with quantum processors are provided. Such quantum processors comprise a plurality of quantum devices together with a plurality of coupling devices. The quantum processor is initialized by setting states of the quantum devices and coupling devices and allowed to evolve to a final state which approximates a natural ground state of the computational problem. The final state can include values of nodes arranged in a lattice in the quantum processor and can represent a solution to the computational processor. The computational problem can have complexity P, NP, NP-Hard, or NP-Complete and may be mapped to a quantum processor with nearest-neighbor and next-nearest-neighbor couplings. The solution to the computational problem can be read out from the quantum processor and transmitted as a data signal embodied in a carrier wave.
1. A method of determining a result for a computational problem using a quantum processor, the method comprising:
(i) initializing the quantum processor to an initial state, wherein the quantum processor comprises a plurality of quantum devices and a plurality of coupling devices, and wherein each coupling device in the plurality of coupling devices couples a pair of quantum devices in the plurality of quantum devices, wherein initializing the quantum processor comprises setting a state of at least one of the quantum devices in the plurality of quantum devices and setting a coupling strength of at least one of the coupling devices in the plurality of coupling devices;
(ii) allowing the quantum processor to evolve to a final state wherein the final state approximates a natural ground state of the computational problem;
(iii) reading out a final state of at least one quantum device in the plurality of quantum devices thereby determining the result for the computational problem; and
(iv) generating a carrier wave embodying a data signal comprising the result of the computational problem.
2. The method of claim 1 , wherein generating a carrier wave embodying a data signal comprising the result of the computational problem includes generating a carrier wave embodying a data signal comprising a respective value for each node in a plurality of nodes;
wherein the plurality of nodes are at least two nodes in a lattice of nodes in the quantum processor, and wherein each node in the lattice of nodes is a quantum device in the plurality of quantum devices; and
wherein a value of at least one node in the plurality of nodes individually or collectively represents a solution to the computational problem that has been solved by evolving the quantum processor at a time after a graph representing the computational problem has been mapped onto at least a portion of the lattice.
3. The method of claim 2 , wherein the computational problem is selected from the group consisting of a problem having a complexity of P, a problem having a complexity of NP, a problem having a complexity of NP-Hard, and a problem having a complexity of NP-Complete.
4. The method of claim 2 , wherein the plurality of nodes comprises at least 16 nodes.
5. The method of claim 2 , wherein the respective value of a node in the plurality of nodes is a binary value.
6. The method of claim 2 , wherein the graph is selected from the group consisting of K 5 , K 3,3 , an expansion of Ks, and an expansion of K 3,3 .
7. A computer system, comprising:
means for inputting a computational problem to be solved, wherein the computational problem is selected from the group consisting of a problem having a complexity of P, a problem having a complexity of NP, a problem having a complexity of NP-Hard, and a problem having a complexity of NP-Complete;
means for mapping the computational problem onto a quantum processor, wherein the quantum processor comprises qubit means and means for coupling nearest-neighbor and next-nearest neighbor qubit means;
means for obtaining a solution to the computational problem using the quantum processor;
means for outputting the solution of the computational problem; and
means for transmitting the solution as a data signal embodied in a carrier wave.