29 research outputs found
Sympathetic cooling of and for quantum logic
We demonstrate the cooling of a two species ion crystal consisting of one
and one ion. Since the respective cooling transitions of
these two species are separated by more than 30 nm, laser manipulation of one
ion has negligible effect on the other even when the ions are not individually
addressed. As such this is a useful system for re-initializing the motional
state in an ion trap quantum computer without affecting the qubit information.
Additionally, we have found that the mass difference between ions enables a
novel method for detecting and subsequently eliminating the effects of radio
frequency (RF) micro-motion.Comment: Submitted to PR
Self-adapting method for the localization of quantum critical points using Quantum Monte Carlo techniques
A generalization to the quantum case of a recently introduced algorithm (Y.
Tomita and Y. Okabe, Phys. Rev. Lett. {\bf 86}, 572 (2001)) for the
determination of the critical temperature of classical spin models is proposed.
We describe a simple method to automatically locate critical points in
(Quantum) Monte Carlo simulations. The algorithm assumes the existence of a
finite correlation length in at least one of the two phases surrounding the
quantum critical point. We illustrate these ideas on the example of the
critical inter-chain coupling for which coupled antiferromagnetic S=1 spin
chains order at T=0. Finite-size scaling relations are used to determine the
exponents, and in agreement with previous
estimates.Comment: 5 pages, 3 figures, published versio
Single Atom Cooling by Superfluid Immersion: A Non-Destructive Method for Qubits
We present a scheme to cool the motional state of neutral atoms confined in
sites of an optical lattice by immersing the system in a superfluid. The motion
of the atoms is damped by the generation of excitations in the superfluid, and
under appropriate conditions the internal state of the atom remains unchanged.
This scheme can thus be used to cool atoms used to encode a series of entangled
qubits non-destructively. Within realisable parameter ranges, the rate of
cooling to the ground state is found to be sufficiently large to be useful in
experiments.Comment: 14 pages, 9 figures, RevTeX