Quantum dynamics in a camelback potential of a dc SQUID.
We investigate a quadratic-quartic anharmonic oscillator formed by a potential well between two potential barriers. We realize this novel potential with a dc SQUID at near-zero current bias and flux bias near half a flux quantum. Escape out of the central well can occur via tunneling through either of the two barriers. We find good agreement with a generalized double-path macroscopic quantum tunneling theory. We also demonstrate an "optimal line" in current and flux bias along which the oscillator, which can be operated as a phase qubit, is insensitive to decoherence due to low-frequency current fluctuations.
Hoskinson
E
E
Institut Néel, C.N.R.S.-Université Joseph Fourier, BP 166, 38042 Grenoble-cedex 9, France.
Lecocq
F
F
Didier
N
N
Fay
A
A
Hekking
F W J
FW
Guichard
W
W
Buisson
O
O
Dolata
R
R
Mackrodt
B
B
Zorin
A B
AB