Four-qubit device with mixed couplings.
We present the first experimental results on a device with more than two superconducting qubits. The circuit consists of four three-junction flux qubits, with simultaneous ferro- and antiferromagnetic coupling implemented using shared Josephson junctions. Its response, which is dominated by the ground state, is characterized using low-frequency impedance measurement with a superconducting tank circuit coupled to the qubits. The results are found to be in excellent agreement with the quantum-mechanical predictions.
Institute for Physical High Technology, P.O. Box 100239, D-07702 Jena, Germany.
M
M
Grajcar
A
A
Izmalkov
S H W
SH
van der Ploeg
S
S
Linzen
T
T
Plecenik
Th
T
Wagner
U
U
Hübner
E
E
Il'ichev
H-G
HG
Meyer
A Yu
AY
Smirnov
Peter J
PJ
Love
Alec
A
Maassen van den Brink
M H S
MH
Amin
S
S
Uchaikin
A M
AM
Zagoskin