196 research outputs found
Relativistic general-order coupled-cluster method for high-precision calculations: Application to Al+ atomic clock
We report the implementation of a general-order relativistic coupled-cluster
method for performing high-precision calculations of atomic and molecular
properties. As a first application, the static dipole polarizabilities of the
ground and first excited states of Al+ have been determined to precisely
estimate the uncertainty associated with the BBR shift of its clock frequency
measurement. The obtained relative BBR shift is -3.66+-0.44 for the 3s^2
^1S_0^0 --> 3s3p ^3P_0^0 transition in Al+ in contrast to the value obtained in
the latest clock frequency measurement, -9+-3 [Phys. Rev. Lett. 104, 070802
(2010)]. The method developed in the present work can be employed to study a
variety of subtle effects such as fundamental symmetry violations in atoms.Comment: 4 pages, 3 tables, submitte
Building one molecule from a reservoir of two atoms
Chemical reactions typically proceed via stochastic encounters between
reactants. Going beyond this paradigm, we combine exactly two atoms into a
single, controlled reaction. The experimental apparatus traps two individual
laser-cooled atoms (one sodium and one cesium) in separate optical tweezers and
then merges them into one optical dipole trap. Subsequently, photoassociation
forms an excited-state NaCs molecule. The discovery of previously unseen
resonances near the molecular dissociation threshold and measurement of
collision rates are enabled by the tightly trapped ultracold sample of atoms.
As laser-cooling and trapping capabilities are extended to more elements, the
technique will enable the study of more diverse, and eventually more complex,
molecules in an isolated environment, as well as synthesis of designer
molecules for qubits
Preparation of Dicke States in an Ion Chain
We have investigated theoretically and experimentally a method for preparing
Dicke states in trapped atomic ions. We consider a linear chain of ion
qubits that is prepared in a particular Fock state of motion, . The
phonons are removed by applying a laser pulse globally to the qubits, and
converting the motional excitation to flipped spins. The global nature of
this pulse ensures that the flipped spins are shared by all the target ions
in a state that is a close approximation to the Dicke state \D{N}{m}. We
calculate numerically the fidelity limits of the protocol and find small
deviations from the ideal state for and . We have demonstrated
the basic features of this protocol by preparing the state \D{2}{1} in two
Mg target ions trapped simultaneously with an Al
ancillary ion.Comment: 5 pages, 2 figure
Quantum information processing with trapped ions
Experiments directed towards the development of a quantum computer based on
trapped atomic ions are described briefly. We discuss the implementation of
single qubit operations and gates between qubits. A geometric phase gate
between two ion qubits is described. Limitations of the trapped-ion method such
as those caused by Stark shifts and spontaneous emission are addressed.
Finally, we describe a strategy to realize a large-scale device.Comment: Article submitted by D. J. Wineland ([email protected])
for proceeding of the Discussion Meeting on Practical Realisations of Quantum
Information Processing, held at the Royal Society, Nov. 13,14, 200
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