Search results for "Trap"

Quantum chemical simulations of hole self-trapping in semi-ionic crystals

1994

A novel formalism is presented for reliable calculations of the energetics of hole self-trapping in semi-ionic solids with mixed valence bands. Unlike previous model-Hamiltonian-type approaches, it is based on self-consistent quantum chemical INDO simulations of the atomistic and electronic structure of a self-trapped hole, making no a priori assumptions about a particular form of its localization (if any). This formalism is applied to the problem of hole self-trapping in corundum crystals (a -A1203). The hole self-trapping is found to be energetically favorable in the form of a diatomic 02 molecule with strong covalent bonding quite similar to the self-trapped hole (VK-center) in alkali ha…

The Ramsey method in high-precision mass spectrometry with Penning traps: Theoretical foundations

2007

Abstract This paper presents in a quantum mechanical framework a theoretical description of the interconversion of the magnetron and modified cyclotron motional modes of ions in a Penning trap due to excitation by external rf-quadrupole fields with a frequency near the true cyclotron frequency. The work aims at a correct description of the resonance line shapes that are observed in connection with more complicated excitation schemes using several excitation pulses, such as Ramsey’s method of separated oscillating fields. Quantum mechanical arguments together with the “rotating wave approximation” suggest a model Hamiltonian that permits a rigorous solution of the corresponding Heisenberg eq…

2014

We investigate the performance of different control techniques for ion transport in state-of-the-art segmented miniaturized ion traps. We employ numerical optimization of classical trajectories and quantum wavepacket propagation as well as analytical solutions derived from invariant based inverse engineering and geometric optimal control. We find that accurate shuttling can be performed with operation times below the trap oscillation period. The maximum speed is limited by the maximum acceleration that can be exerted on the ion. When using controls obtained from classical dynamics for wavepacket propagation, wavepacket squeezing is the only quantum effect that comes into play for a large ra…

Doppler free ?dark resonances? for hyperfine measurements and isotope shifts in Ca+ isotopes in a Paul trap

1995

We have observed “dark resonances” in theA-type level structure, formed by the 4S1/2 ground state, the 4P1/2 excited state and the low lying metastable 3D3/2 state in the Calcium ion, confined in a Paul radio-frequency trap. These Doppler-free and potentially very narrow resonances were used to determine the magnetic dipole hyperfine interaction constant A for the 4P1/2 and 3D3/2 state of43Ca+, giving −142(8) MHz and −48.3(1.6) MHz, respectively. From measurements of the P-D (E1) and S-D (E2) transition wavelength in a mixture of43Ca+ and40Ca+ we determined the isotope shifts of these lines.

High-precision hyperfine spectroscopy inM1-M1 double-resonance transitions on trappedPb+207

1992

Optical pumping of the ground state of $^{207}\mathrm{Pb}^{+}$ ions, confined in a Paul ion trap on the weak 6${\mathit{P}}_{1/2\mathrm{\ensuremath{-}}}$6${\mathit{P}}_{3/2}$ M1 transition at \ensuremath{\lambda}=710 nm, and consequent magnetic-dipole transitions between the ground-state hyperfine Zeeman levels have resulted in an A factor of 12 968 180 601.61(0.22) Hz and linewidth of 0.5 Hz. The value includes corrections of Zeeman shifts from residual magnetic fields and second-order Doppler shifts in the several-eV-deep trap potential, while the ions were cooled by He buffer gas. Two M1 quanta have been applied simultaneously in a double-resonance experiment.

ExperimentalgJfactor in the metastable 5D3/2level ofBa+

1996

The Zeeman splitting of the metastable 5${\mathit{D}}_{3/2}$ level of $^{138}\mathrm{Ba}^{+}$ in a magnetic field of 6 T has been measured in a laser-microwave double resonance experiment in a Penning ion trap. The magnetic field at the ion's position is determined by the cyclotron frequency of electrons stored in the same trap. From the ratio of both transition frequencies we obtain a ${\mathit{g}}_{\mathit{J}}$ value of 0.799 327 8(3). As a by-product, we confirmed earlier measurements on the 6${\mathit{S}}_{1/2}$ ground-state ${\mathit{g}}_{\mathit{J}}$ factor to 2.002 492 2(10). The precision in both experiments is sufficient to test relativistic many-body calculations. \textcopyright{}…

Hyperfine structure measurements in the

1997

Clouds of stable and unstable Eu+ isotopes have been confined in a Paul trap, each containing about 105 particles. In a microwave-optical double resonance experiment several hyperfine separations in the 4f7 6s 7S3 exited level have been measured with the experimental uncertainties ranging between 10-8 and 3×10-6. These experiments have confirmed that also in the case of an excited level with a large number of hyperfine or Zeeman sublevels the microwave-optical double resonance technique in a Paul trap can be useful for precise hyperfine structure investigation. The hyperfine coupling constants A and B have been determined for the isotopes 153Eu+, 151Eu+, 150Eu+ and 148Eu+. The results compl…

Precise determination of the ground state hyperfine structure splitting of43Ca II

1994

We have performed a laser microwave double resonance experiment on43Ca+ ions stored in a Paul ion trap. The ground state hfs splitting has been determined to Δν=3 225 608 286. 4(3) Hz. The value is corrected for small Zeeman, Stark and second order Doppler shifts as well as for light shift effects caused by the laserfields. The uncertainty is mainly determined by the errors of these corrections.

Experimental ground stateg J-factor of Ba+ in a Penning ion trap

1993

We observed the Zeeman-splitting of the 6S1/2 – 6P1/2 resonance transition of Ba+-ions (493.4 nm) in a 6T magnetic field. The ions were stored in a Penning quadrupole trap. We polarized the ground state by optical pumping and in a microwave-optical double resonance experiment we measured the ground state Zeeman-splitting. From the resonance frequency and the cyclotron frequency of electrons stored in the same trap we derived theg-factor of the 6S1/2 state. The result isgJ(6S1/2)=2.002 490 6(11), in reasonable agreement with recent calculations.

Ion trap nuclear resonance on $\mathsf{^{151}Eu^ + }$

2003

Laser-microwave double resonance techniques applied to a cloud of a natural mixture of Eu + isotopes confined in a Penning trap has been used to induce and detect nuclear Zeeman transitions. In spite of the complex level structure of Eu + and overlapping spectra from the two isotopes five different $\Delta m_I = 1$ transitions could be observed from which the nuclear magnetic moment can be derived. We obtain for 151 Eu + g I = 1.377 34(6) demonstrating the potential for high accuracy of the technique. The experiment can be considered as a feasibility test that precise spectroscopy data using the ion storage technique can be obtained of very complex ions and under unfavourable conditions.