Showing papers by "Rainer Blatt published in 2002"
TL;DR: The quadrupole S(1/2)-D(5/2) optical transition of a single trapped Ca+ ion is coherently coupled to the standing wave field of a high finesse cavity and deterministic coupling of the cavity mode to the ion's vibrational state is achieved.
Abstract: The quadrupole S(1/2)-D(5/2) optical transition of a single trapped Ca+ ion, well suited for encoding a quantum bit of information, is coherently coupled to the standing wave field of a high finesse cavity. The coupling is verified by observing the ion's response to both spatial and temporal variations of the intracavity field. We also achieve deterministic coupling of the cavity mode to the ion's vibrational state by selectively exciting vibrational state-changing transitions and by controlling the position of the ion in the standing wave field with nanometer precision.
265 citations
TL;DR: In this article, the stability of a qubit based on the transition of single ionic ions in a linear Paul trap was investigated. But the stability was not shown to be stable.
Abstract: Two-level ionic systems, where quantum information is encoded in long lived states (qubits), are discussed extensively for quantum information processing. We present a collection of measurements which characterize the stability of a qubit based on the $S_{1/2}$--$D_{5/2}$ transition of single $^{40}$Ca$^+$ ions in a linear Paul trap. We find coherence times of $\simeq$1 ms, discuss the main technical limitations and outline possible improvements.
97 citations
TL;DR: In this paper, the authors investigated the dynamical response of an optical Fabry-Perot cavity and observed oscillations in transmitted and reflected light intensity if the frequency of the incoupled light field is rapidly changed.
Abstract: The dynamical response of an optical Fabry–Perot cavity is investigated experimentally. We observe oscillations in the transmitted and the reflected light intensity if the frequency of the incoupled light field is rapidly changed. In addition, the decay of a cavity-stored light field is accelerated if the phase and the intensity of the incoupled light are switched in an appropriate way. The theoretical model by
M. J.
Lawrence
[J. Opt. Soc. Am. B16, 523 (1999)] agrees with our observations.
29 citations
01 Jan 2002
TL;DR: In this article, a novel cooling scheme based on electromagnetically induced transparency on the S↓/2 -P↓ /2 manifold was proposed to achieve simultaneous ground state cooling of two motional sidebands 1.7 MHz apart.
Abstract: For quantum information experiments we have cooled one and two 40Ca+ions to the ground state of vibration with up to 99.9% probability, using resolved sideband cooling on the optical S1/2-D5/2 quadrupole transition. Implementing a novel cooling scheme based on electromagnetically induced transparency on the S↓/2 -P↓/2 manifold we have achieved simultaneous ground state cooling of two motional sidebands 1.7 MHz apart. Coherent quantum state manipulation on the S1/2 -D5/2 quadrupole transition at 729 nm was demonstrated and up to 30 Rabi oscillations within 1.4 ms have been observed starting from the motional ground state and from the n=1 Fock state. In a linear rf-trap two ions were cooled to the ground state of motion and individual addressing of the ions with laser pulses is achieved.
3 citations
01 Jun 2002
TL;DR: In this paper, a single photon emitted by a single trapped atom which interacts with its mirror image over a distance of 50 cm was recorded by retroreflecting the fluorescence of a trapped Ba+ ion with a high-quality lens and a mirror 25 cm away.
Abstract: The spontaneous emission of an atom is inhibited and enhanced when the atom is placed into a structured dielectric environment [1]. When another atom of the same kind is nearby, their spontaneous emission may exhibit cooperative suband superradiance [2]. We study these most fundamental quantum optical processes by recording single photons emitted by a single trapped atom which interacts with its mirror image over a distance of 50 cm: By retroreflecting the fluorescence of a single trapped Ba+ ion with a high-quality lens and a mirror 25 cm away, we observe interference fringes with 72% visibility as the mirror distance varies. Simultaneous observation of the light transmitted through the mirror shows the population of the upper level to vary in anticorrelation with the interference fringes, which indicates inhibition and enhancement of a single atom's single spontaneous emission events. When two ions are trapped, they interfere with each other's mirror images, which indicates superand subradiance mediated by the distant mirror. In this case the fringe visibility is 5%. The experiment allows to study variations in the vacuum fluctuations around a trapped ion on a sub-optical scale and to determine its position with respect to the mirror with nanometerresolution.
2 citations
01 Jun 2002
TL;DR: In this article, a laser cooling method for trapped atoms is presented which achieves ground state cooling by exploiting quantum interference in a Λ-shaped arrangement of atomic levels driven by two lasers.
Abstract: A laser cooling method for trapped atoms is presented which achieves ground state cooling by exploiting quantum interference in a Λ-shaped arrangement of atomic levels driven by two lasers.1 The scheme is technically simpler than existing methods of sideband cooling, yet it can be significantly more efficient, in particular when several motional modes are involved. We have applied the method to a single Calcium ion in a Paul trap,2 coupling a single laser to the Zeeman structure of its S1/2 → P1/2 dipole transition at 397 nm. We have achieved more than 90% ground-state occupation probability. By suitably tuning the laser parameters, we obtain simultaneous ground-state cooling of two oscillator modes. This is of great practical importance for the implementation of quantum logic schemes with trapped ions.
2 citations