Showing papers by "Rainer Blatt published in 2007"
TL;DR: The analysis concerns the non-Markovian regime of the ion-mirror interaction and reveals the field establishment in a half-cavity interferometer.
Abstract: Photon correlations are investigated for a single laser-excited ion trapped in front of a mirror. Varying the relative distance between the ion and the mirror, photon correlation statistics can be tuned smoothly from an antibunching minimum to a bunchinglike maximum. Our analysis concerns the non-Markovian regime of the ion-mirror interaction and reveals the field establishment in a half-cavity interferometer.
76 citations
TL;DR: In this paper, a frequency-chirped laser pulse with a Gaussian amplitude envelope was used to transfer a single trapped ion from the ground state S1/2 to the metastable state D5/2.
Abstract: We report adiabatic passage experiments with a single trapped ion. By applying a frequency-chirped laser pulse with a Gaussian amplitude envelope, we reach a transfer efficiency of 0.99(1) on an optical transition from the electronic ground state S1/2 to the metastable state D5/2. This transfer method is shown to be insensitive to the accurate setting of laser parameters, and therefore is suitable as a robust tool for ion-based quantum computing.
73 citations
TL;DR: In this article, the performance of a quantum teleportation algorithm implemented on an ion trap quantum computer is investigated in terms of the teleportation fidelity of six input states evenly distributed over the Bloch sphere.
Abstract: The performance of a quantum teleportation algorithm implemented on an ion trap quantum computer is investigated. First the algorithm is analysed in terms of the teleportation fidelity of six input states evenly distributed over the Bloch sphere. Furthermore, a quantum process tomography of the teleportation algorithm is carried out which provides almost complete knowledge about the algorithm.
50 citations
TL;DR: In this paper, the authors discuss techniques that allow for long coherence times in laser spectroscopy experiments with two trapped ions and show that for this purpose not only entangled ions prepared in decoherence-free subspaces can be used but also a pair of ions that are not entangled but subject to the same kind of phase noise.
Abstract: We discuss techniques that allow for long coherence times in laser spectroscopy experiments with two trapped ions. We show that for this purpose not only entangled ions prepared in decoherence-free subspaces can be used but also a pair of ions that are not entangled but subject to the same kind of phase noise. We apply this technique to a measurement of the electric quadrupole moment of the 3d2D5/2 state of 40Ca+ and to a measurement of the line width of an ultra-stable laser exciting a pair of 40Ca+ ions.
47 citations
TL;DR: In this article, the performance of a quantum teleportation algorithm implemented on an ion trap quantum computer is investigated in terms of the teleportation fidelity of six input states evenly distributed over the Bloch sphere.
Abstract: The performance of a quantum teleportation algorithm implemented on an ion trap quantum computer is investigated. First the algorithm is analyzed in terms of the teleportation fidelity of six input states evenly distributed over the Bloch sphere. Furthermore, a quantum process tomography of the teleportation algorithm is carried out which provides almost complete knowledge about the algorithm.
36 citations
TL;DR: In this paper, trapped, laser-cooled rubidium atoms are transferred between two strongly focused, horizontal, orthogonally intersecting laser beams and the transfer efficiency is studied as a function of the vertical distance between the beam axes.
Abstract: Trapped, laser-cooled rubidium atoms are transferred between two strongly focused, horizontal, orthogonally intersecting laser beams. The transfer efficiency is studied as a function of the vertical distance between the beam axes. Optimum transfer is found when the distance equals the beam waist radius. Numerical simulations reproduce well the experimental results.
30 citations
TL;DR: In this article, the hyperfine structure constants of the metastable level of the quadrupole transition at the $4s\phantom{\rule{0.2em}{0ex}}^{2}S_{5∕2}$ quadrupoles were determined by laser spectroscopy using a single trapped ion.
Abstract: The hyperfine structure of the $4s\phantom{\rule{0.2em}{0ex}}^{2}S_{1∕2}\text{\ensuremath{-}}3d\phantom{\rule{0.2em}{0ex}}^{2}S_{5∕2}$ quadrupole transition at $729\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ in $^{43}\mathrm{Ca}^{+}$ has been investigated by laser spectroscopy using a single trapped $^{43}\mathrm{Ca}^{+}$ ion. We determine the hyperfine structure constants of the metastable level as ${A}_{{D}_{5∕2}}=3.8931(2)\phantom{\rule{0.2em}{0ex}}\mathrm{MHz}$ and ${B}_{{D}_{5∕2}}=4.241(4)\phantom{\rule{0.2em}{0ex}}\mathrm{MHz}$. The isotope shift of the transition with respect to $^{40}\mathrm{Ca}^{+}$ was measured to be ${\ensuremath{\Delta}}_{\mathrm{iso}}^{43,40}=4134.713(5)\phantom{\rule{0.2em}{0ex}}\mathrm{MHz}$. We demonstrate the existence of transitions that become independent of the first-order Zeeman shift at nonzero low magnetic fields. These transitions might be better suited for building a frequency standard than the well-known ``clock transitions'' between $m=0$ levels at zero magnetic field.
30 citations
TL;DR: The spectral brightness of the two-photon source is quantified and shown to be comparable to parametric down-conversion devices.
Abstract: A single trapped ion is converted into a pseudo-two-photon source by splitting its resonance fluorescence, delaying part of it and by recombining both parts on a beam splitter. A destructive two-photon interference is observed with a contrast reaching 83(5)%. The spectral brightness of our two-photon source is quantified and shown to be comparable to parametric down-conversion devices.
11 citations
TL;DR: In this article, the authors discuss techniques that allow for long coherence times in laser spectroscopy experiments with two trapped ions and show that for this purpose not only entangled ions prepared in decoherence-free subspaces can be used but also a pair of ions that are not entangled but subject to the same kind of phase noise.
Abstract: We discuss techniques that allow for long coherence times in laser spectroscopy experiments with two trapped ions. We show that for this purpose not only entangled ions prepared in decoherence-free subspaces can be used but also a pair of ions that are not entangled but subject to the same kind of phase noise. We apply this technique to a measurement of the electric quadrupole moment of the 3d D5/2 state of 40Ca+ and to a measurement of the linewidth of an ultrastable laser exciting a pair of 40Ca+ ions.
10 citations
10 citations
13 Jun 2007
TL;DR: In this article, the authors demonstrate precision spectroscopy with two trapped Ca+ions in a decoherence-free subspace with specifically designed entangled states, and demonstrate that the entangled strings serve as a quantum register to produce and characterize multipartite quantum states.
Abstract: Strings of trapped Ca+ions serve as a quantum register to produce and characterize multipartite quantum states. Using a decoherence-free subspace with specifically designed entangled states we demonstrate precision spectroscopy with two trapped Ca+ions.
01 Jan 2007
TL;DR: In this paper, a new version of the XMDS code-generator for computational simulations, with many new features and applications to quantum-atom optics, is presented. But it is not suitable for quantum computing.
Abstract: We outline a new version of the XMDS code-generator for computational simulations, with many new features and applications to quantum-atom optics.