Observation of Berry's Phase in a Solid-State Qubit
P. J. Leek,1*
J. M. Fink,1
A. Blais,2
R. Bianchetti,1
M. Göppl,1
J. M. Gambetta,3,4
D. I. Schuster,4
L. Frunzio,4
R. J. Schoelkopf,4
A. Wallraff1*
In quantum information science, the phase of a wave function plays an important role in encoding information. Although most experiments in this field rely on dynamic effects to manipulate this information, an alternative approach is to use geometric phase, which has been argued to have potential fault tolerance. We demonstrated the controlled accumulation of a geometric phase, Berry's phase, in a superconducting qubit; we manipulated the qubit geometrically by means of microwave radiation and observed the accumulated phase in an interference experiment. We found excellent agreement with Berry's predictions and also observed a geometry-dependent contribution to dephasing.
1 Department of Physics, Eidgenössische Technische Hochschule (ETH) Zürich, Schafmattstrasse 16, 8093 Zürich, Switzerland.
2 Département de Physique, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1, Canada.
3 Institute for Quantum Computing and Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
4 Departments of Applied Physics and Physics, Yale University, New Haven, CT 06520, USA.
* To whom correspondence should be addressed. E-mail: leek{at}phys.ethz.ch (P.J.L.); andreas.wallraff{at}phys.ethz.ch (A.W.)
