@article {1305,
title = {Multilevel effects in the Rabi oscillations of a Josephson phase qubit},
journal = {Physical Review B},
volume = {78},
year = {2008},
month = {2008/9/15},
abstract = { 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.
},
doi = {10.1103/PhysRevB.78.104510},
url = {http://arxiv.org/abs/0806.4711v2},
author = {S. K. Dutta and Frederick W. Strauch and R. M. Lewis and Kaushik Mitra and Hanhee Paik and T. A. Palomaki and Eite Tiesinga and J. R. Anderson and Alex J. Dragt and C. J. Lobb and F. C. Wellstood}
}
@article {1404,
title = {Theoretical analysis of perfect quantum state transfer with superconducting qubits
},
journal = {Physical Review B},
volume = {78},
year = {2008},
month = {2008/9/24},
abstract = { Superconducting quantum circuits, fabricated with multiple layers, are
proposed to implement perfect quantum state transfer between nodes of a
hypercube network. For tunable devices such as the phase qubit, each node can
transmit quantum information to any other node at a constant rate independent
of the distance between qubits. The physical limits of quantum state transfer
in this network are theoretically analyzed, including the effects of disorder,
decoherence, and higher-order couplings.
},
doi = {10.1103/PhysRevB.78.094516},
url = {http://arxiv.org/abs/0708.0577v3},
author = {Frederick W. Strauch and Carl J. Williams}
}
@article {1292,
title = {Tunneling phase gate for neutral atoms in a double-well lattice},
journal = {Physical Review A},
volume = {77},
year = {2008},
month = {2008/5/12},
abstract = { We propose a new two--qubit phase gate for ultra--cold atoms confined in an
experimentally realized tilted double--well optical lattice [Sebby--Strabley et
al., Phys. Rev. A {\bf 73} 033605 (2006)]. Such a lattice is capable of
confining pairs of atoms in a two--dimensional array of double--well potentials
where control can be exercised over the barrier height and the energy
difference of the minima of the two wells (known as the {\textquoteleft}{\textquoteleft}tilt{\textquoteright}{\textquoteright}). The four
lowest single--particle motional states consist of two pairs of motional states
in which each pair is localized on one side of the central barrier, allowing
for two atoms confined in such a lattice to be spatially separated qubits. We
present a time--dependent scheme to manipulate the tilt to induce tunneling
oscillations which produce a collisional phase gate. Numerical simulations
demonstrate that this gate can be performed with high fidelity.
},
doi = {10.1103/PhysRevA.77.050304},
url = {http://arxiv.org/abs/0712.1856v1},
author = {Frederick W. Strauch and Mark Edwards and Eite Tiesinga and Carl J. Williams and Charles W. Clark}
}