1,796 research outputs found
Lifetime of Kaonium
The kaon--antikaon system is studied in both the atomic and the strongly
interacting sector. We discuss the influence of the structures of the
and the mesons on the lifetime of kaonium. The strong
interactions are generated by vector meson exchange within the framework of the
standard invariant effective Lagrangian. In the atomic
sector, the energy levels and decay widths of kaonium are determined by an
eigenvalue equation of the Kudryavtsev--Popov type, with the strong interaction
effects entering through the complex scattering length for scattering
and annihilation. The presence of two scalar mesons, and ,
leads to a ground state energy for the kaonium atom that is shifted above the
point Coulomb value by a few hundred eV. The effect on the lifetime for the
kaonium decay into two pions is much more dramatic. This lifetime is reduced by
two orders of magnitude from sec for annihilation in a
pure Coulomb field down to sec when the strong
interactions are included. The analysis of the two photon decay width of the
suggests a generalization of the molecular picture which reduces the
lifetime of kaonium still further to .Comment: 33 pages, 12 figures;3 new figures and new comment concerning the a
Two-dimensional spectroscopy for the study of ion coulomb crystals.
Ion Coulomb crystals are currently establishing themselves as a highly controllable test bed for mesoscopic systems of statistical mechanics. The detailed experimental interrogation of the dynamics of these crystals, however, remains an experimental challenge. In this work, we show how to extend the concepts of multidimensional nonlinear spectroscopy to the study of the dynamics of ion Coulomb crystals. The scheme we present can be realized with state-of-the-art technology and gives direct access to the dynamics, revealing nonlinear couplings even in the presence of thermal excitations. We illustrate the advantages of our proposal showing how two-dimensional spectroscopy can be used to detect signatures of a structural phase transition of the ion crystal, as well as resonant energy exchange between modes. Furthermore, we demonstrate in these examples how different decoherence mechanisms can be identified
Ground State Energy of the One-Component Charged Bose Gas
The model considered here is the `jellium' model in which there is a uniform,
fixed background with charge density in a large volume and in
which particles of electric charge and mass move --- the
whole system being neutral. In 1961 Foldy used Bogolubov's 1947 method to
investigate the ground state energy of this system for bosonic particles in the
large limit. He found that the energy per particle is in this limit, where .
Here we prove that this formula is correct, thereby validating, for the first
time, at least one aspect of Bogolubov's pairing theory of the Bose gasComment: 38 pages latex. Typos corrected.Lemma 6.2 change
Multi-qubit gate with trapped ions for microwave and laser-based implementation
A proposal for a phase gate and a Mølmer–Sørensen gate in the dressed state basis is presented. In order to perform the multi-qubit interaction, a strong magnetic field gradient is required to couple the phonon-bus to the qubit states. The gate is performed using resonant microwave driving fields together with either a radio-frequency (RF) driving field, or additional detuned microwave driving fields. The gate is robust to ambient magnetic field fluctuations due to an applied resonant microwave driving field. Furthermore, the gate is robust to fluctuations in the microwave Rabi frequency and is decoupled from phonon dephasing due to a resonant RF or a detuned microwave driving field. This makes this new gate an attractive candidate for the implementation of high-fidelity microwave based multi-qubit gates. The proposal can also be realized in laser-based set-ups
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