Far-from-equilibrium noise-heating and laser-cooling dynamics in radio-frequency Paul traps (original) (raw)

Ion dynamics in a linear radio-frequency trap with a single cooling laser

Physical Review A, 2010

We analyse the possibility of cooling ions with a single laser beam, due to the coupling between the three components of their motion induced by the Coulomb interaction. For this purpose, we numerically study the dynamics of ion clouds of up to 140 particles, trapped in a linear quadrupole potential and cooled with a laser beam propagating in the radial plane. We use Molecular Dynamics simulations and model the laser cooling by a stochastic process. For each component of the motion, we systematically study the dependence of the temperature with the anisotropy of the trapping potential. Results obtained using the full radio-frequency (rf) potential are compared to those of the corresponding pseudo-potential. In the rf case, the rotation symmetry of the potential has to be broken to keep ions inside the trap. Then, as for the pseudo-potential case, we show that the efficiency of the Coulomb coupling to thermalize the components of motion depends on the geometrical configuration of the cloud. Coulomb coupling appears to be not efficient when the ions organise as a line or a pancake and the three components of motion reach the same temperature only if the cloud extends in three dimensions.

Quantum Stochastic Heating of a Trapped Ion

Conference on Coherence and Quantum Optics, 2007

The resonant heating of a harmonically trapped ion by a standing-wave light field is described as a quantum stochastic process combining a coherent Schrödinger evolution with Bohr-Einstein quantum jumps. Quantum and semi-quantum treatments are compared.

Quantum theory of heating of a single trapped ion

The heating of trapped ions due to the interaction with a quantized environment is studied without performing the Born-Markov approximation. A generalized master equation local in time is derived and a novel theoretical approach to solve it analytically is proposed. Our master equation is in the Lindblad form with time dependent coefficients, thus allowing the simulation of the dynamics by means of the Monte Carlo Wave Function (MCWF) method.

Stochastic Cooling for a Single Trapped Ion

We propose a feedback scheme to control the vibrational motion of a single trapped particle based on indirect measurements of its position. It results the possibility of a motional phase space uncertainty contraction corresponding to localise the particle below its thermal equilibrium fluctuations.

Laser cooling of trapped ions: The influence of micromotion

Physical Review A, 1994

Laser cooling of a single trapped ion in a Paul trap is discussed theoretically in the Lamb-Dicke limit, with full consideration of the time dependence of the trapping potential. Resulting mean kinetic energies are de6ned as time averages over one period of the micromotion and are compared with 6nal temperatures expected from the laser cooling treatment with harmonic traps. For laser-atom detunings close to the micromotion frequency the results dier signi6cantly from those expected for a harmonic trap potential. A physical interpretation is given and simple formulas are derived for the strong con6nement case.

Laser cooling of trapped ions

Journal of The Optical Society of America B-optical Physics, 2003

Trapped and laser-cooled ions are increasingly used for a variety of modern high-precision experiments, for frequency standard applications, and for quantum information processing. Therefore laser cooling of trapped ions is reviewed, the current state of the art is reported, and several new cooling techniques are outlined. The principles of ion trapping and the basic concepts of laser cooling for trapped atoms are introduced. The underlying physical mechanisms are presented, and basic experiments are briefly sketched. Particular attention is paid to recent progress by elucidating several milestone experiments. In addition, a number of special cooling techniques pertaining to trapped ions are reviewed; open questions and future research lines are indicated.

Energy fluctuations induced by stochastic frequency changes in atom traps

Physical Review A, 2003

We study the quantum description of energy fluctuations induced by stochastic changes in the frequency of atom traps. Using the connection between classical and quantum descriptions of parametric oscillators, the classical cumulant expansion method is used to obtain quantum results beyond standard perturbation theory. Both the case of static and time-dependent traps are explicitly worked out.

Stochastic cooling of atoms using lasers

Physical Review A, 1998

We propose a method to laser-cool atoms based on stochastic cooling, first developed at CERN to cool antiprotons. Fluctuations in the momentum distribution will be detected in a pump-probe configuration with far-detuned lasers, and the appropriate correction kick will be accomplished with optical dipole potentials. Each stage of an iterative cooling process will involve measurement and feedback, with phase space

Transverse confinement in stochastic cooling of trapped atoms

Journal of Optics B: Quantum and Semiclassical Optics, 2004

Stochastic cooling of trapped atoms is considered for a laser-beam configuration with beam waists equal or smaller than the extent of the atomic cloud. It is shown, that various effects appear due to this transverse confinement, among them heating of transverse kinetic energy. Analytical results of the cooling in dependence on size and location of the laser beam are presented for the case of a non-degenerate vapour.