TY - JOUR
T1 - Multilevel effects in the Rabi oscillations of a Josephson phase qubit
JF - Physical Review B
Y1 - 2008
A1 - S. K. Dutta
A1 - Frederick W. Strauch
A1 - R. M. Lewis
A1 - Kaushik Mitra
A1 - Hanhee Paik
A1 - T. A. Palomaki
A1 - Eite Tiesinga
A1 - J. R. Anderson
A1 - Alex J. Dragt
A1 - C. J. Lobb
A1 - F. C. Wellstood
AB - We present Rabi oscillation measurements of a Nb/AlOx/Nb dc superconducting quantum interference device (SQUID) phase qubit with a 100 um^2 area junction acquired over a range of microwave drive power and frequency detuning. Given the slightly anharmonic level structure of the device, several excited states play an important role in the qubit dynamics, particularly at high power. To investigate the effects of these levels, multiphoton Rabi oscillations were monitored by measuring the tunneling escape rate of the device to the voltage state, which is particularly sensitive to excited state population. We compare the observed oscillation frequencies with a simplified model constructed from the full phase qubit Hamiltonian and also compare time-dependent escape rate measurements with a more complete density-matrix simulation. Good quantitative agreement is found between the data and simulations, allowing us to identify a shift in resonance (analogous to the ac Stark effect), a suppression of the Rabi frequency, and leakage to the higher excited states.
VL - 78
UR - http://arxiv.org/abs/0806.4711v2
CP - 10
J1 - Phys. Rev. B
U5 - 10.1103/PhysRevB.78.104510
ER -