Measurement of the ground-state flux diagram of three coupled qubits as a first step towards the demonstration of adiabatic quantum computation

摘要

The ground state susceptibility of a system consisting of three flux-qubitswas measured in the complete three dimensional flux space around the commondegeneracy point of the qubits. The system's Hamiltonian could be completelyreconstructed from measurements made far away from the common degeneracy point.The subsequent measurements made around this point show complete agreement withthe theoretical predictions which follow from this Hamiltonian. The groundstate anti-crossings of the system could be read-out directly from thesemeasurements. This allows one to determine the ground-state flux diagram, whichprovides the solution for the non-polynomial optimization problem MAXCUTencoded in the Hamiltonian of the three-flux-qubit system. Our results showthat adiabatic quantum computation can be demonstrated with this systemprovided that the energy gap and/or the speed of the read-out is increased.