Generation of high-fidelity controlled-NOT logic gates by coupled superconducting qubits
Andrei Galiautdinov
Building on the previous results of the Weyl chamber steering method, we demonstrate how to generate high-fidelity controlled-NOT (CNOT) gates by direct application of certain physically relevant Hamiltonians with fixed coupling constants containing Rabi terms. Such Hamiltonians are often used to de ... [Phys. Rev. A 75, 052303 (2007)] published Wed May 2, 2007.
Robust Controlled-NOT Gates from Almost Any Interaction
Charles D. Hill
There are many cases where the interaction between two qubits is not precisely known, but single-qubit operations are available. In this Letter we show how, regardless of an incomplete knowledge of the strength or form of the interaction between two qubits, it is often possible to construct a contro ... [Phys. Rev. Lett. 98, 180501 (2007)] published Tue May 1, 2007.
Spin polarized photocurrent from quantum dots
J. M. Villas-Boas, Sergio E. Ulloa, and A. O. Govorov
We predict strong spin-polarization switching of the photocurrent signal obtained from a single, self-assembled quantum dot photodiode by tuning only the intensity of elliptically polarized light. In the nonlinear mechanism described here, elliptically polarized light creates an effective exchange c ... [Phys. Rev. B 75, 155334 (2007)] published Mon Apr 30, 2007.
Proposal for electron spin relaxation measurements using double-donor excited states in Si quantum computer architectures
M. J. Calderon, Belita Koiller, and S. Das Sarma
The possibility of performing single-spin measurements in Si-based quantum computers using electrons bound to double donors near a barrier interface is assessed. We find that double donors in the ground state require electric fields and tunneling times too large for practical implementations, while ... [Phys. Rev. B 75, 161304 (2007)] published Fri Apr 27, 2007.
Direct observation of the donor nuclear spin in a near-gap bound exciton transition: [sup 31]P in highly enriched [sup 28]Si
M. L. W. Thewalt, A. Yang, M. Steger, D. Karaiskaj, M. Cardona et al.
We report on ultrahigh resolution studies of the bound exciton states associated with the shallow acceptor B and the shallow donor P in highly enriched [sup 28]Si using a tuneable single frequency laser to perform photoluminescence excitation spectroscopy. The linewidths and fine structure of the tr ... [J. Appl. Phys. 101, 081724 (2007)] published Fri Apr 27, 2007.
Low-decoherence flux qubit
J. Q. You, Xuedong Hu, S. Ashhab, and Franco Nori
A flux qubit can have a relatively long decoherence time at the degeneracy point, but away from this point the decoherence time is greatly reduced by dephasing. This limits the practical applications of flux qubits. Here we propose a qubit design modified from the commonly used flux qubit by introdu ... [Phys. Rev. B 75, 140515 (2007)] published Fri Apr 27, 2007.
Errors in trapped-ion quantum gates due to spontaneous photon scattering
R. Ozeri, W. M. Itano, R. B. Blakestad, J. Britton, J. Chiaverini et al.
We analyze the error in trapped-ion, hyperfine qubit, quantum gates due to spontaneous scattering of photons from the gate laser beams. We investigate single-qubit rotations that are based on stimulated Raman transitions and two-qubit entangling phase gates that are based on spin-dependent optical d ... [Phys. Rev. A 75, 042329 (2007)] published Fri Apr 27, 2007.
Thermal Entanglement In The Two - Qubit And Three - Qubit Heisenberg XX Chain
O. Ozcan
Entanglement plays an important role in quantum computation and quantum information processing. It is therefore of interest to investigate the thermal entanglement in Heisenberg models. In this study, we analyze the dependence of entanglement in Heisenberg XX chain on temperature. Moreover we talke ... [AIP Conf. Proc. 899, 720 (2007)] published Fri Apr 27, 2007.