TY  - JOUR
AU  - Willsch, Madita
AU  - Willsch, Dennis
AU  - Jin, Fengping
AU  - De Raedt, Hans
AU  - Michielsen, Kristel
TI  - Real-time simulation of flux qubits used for quantum annealing
JO  - Physical review / A
VL  - 101
IS  - 1
SN  - 2469-9926
CY  - Woodbury, NY
PB  - Inst.
M1  - FZJ-2020-04142
SP  - 012327
PY  - 2020
AB  - The real-time flux dynamics of up to three superconducting quantum interference devices (SQUIDs) are studied by numerically solving the time-dependent Schrödinger equation. The numerical results are used to scrutinize the mapping of the flux degrees of freedom onto two-level systems (the qubits) as well as the performance of the intermediate SQUID as a tunable coupling element. It is shown that the qubit representation yields a good description of the flux dynamics during quantum annealing and the presence of the tunable coupling element does not have negative effects on the overall performance. Additionally, data obtained from a simulation of the dynamics of two-level systems during quantum annealing are compared to experimental data produced by the D-Wave 2000Q quantum annealer. The effects of finite temperature are incorporated in the simulation by coupling the qubit system to a bath of two-level systems. It is shown that an environment modeled as noninteracting two-level systems coupled to the qubits can produce data which matches the experimental data much better than the simulation data of the qubits without coupling to an environment and better than data obtained from a simulation of an environment modeled as interacting two-level systems coupling to the qubits.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000508443000005
DO  - DOI:10.1103/PhysRevA.101.012327
UR  - https://juser.fz-juelich.de/record/885866
ER  -