Carlos Russo

Deterministic single-photon source from a single ion

We realize a deterministic single-photon source from one and the same calcium ion interacting with a high-finesse optical cavity. Photons are created in the cavity with efficiency 88±17%, a tenfold improvement over previous cavity-ion sources. Results of the second-order correlation function are presented, demonstrating a high suppression of two-photon events limited only by background counts. The cavity photon pulse shape is obtained, with good agreement between experiment and simulation. Moreover, theoretical analysis of the temporal evolution of the atomic populations provides relevant information about the dynamics of the process and opens the way to future investigations of a coherent atom–photon interface.

Photon Correlation versus Interference of Single-Atom Fluorescence in a Half-Cavity

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.

Raman spectroscopy of a single ion coupled to a high-finesse cavity

We describe an ion-based cavity-QED system in which the internal dynamics of an atom is coupled to the modes of an optical cavity by vacuum-stimulated Raman transitions. We observe Raman spectra for different excitation polarizations and find quantitative agreement with theoretical simulations. Residual motion of the ion introduces motional sidebands in the Raman spectrum and leads to ion delocalization. The system offers prospects for cavity-assisted resolved-sideband ground-state cooling and coherent manipulation of ions and photons.

A single-photon source based on a single Ca+ ion

We propose a deterministic source of single photons based on the vacuum-stimulated Raman transition of a single Ca+ ion trapped inside a high finesse cavity. Assuming realistic experimental parameters, the efficiency of photon emission into the cavity mode reaches 95%.

Quantum to classical transition in a single-ion laser

‘Quantum’ lasers — with one atom interacting with a single optical mode — do not exhibit a conventional-laser-like threshold in the regime of strong light–matter coupling. A study now shows that a threshold is seen when the coupling strength is reduced, which represents the onset of classical lasing.

Quantum information processing and cavity QED experiments with trapped Ca' ions

Single trapped Ca+ ions, stored in a linear Paul trap and laser-cooled to the ground state of their harmonic quantum motion are used for quantum information processing. As a demonstration, composite laser pulse sequences were used to implement phase gate and CNOT gate operation. For this, Stark shifts on the qubit transitions were precisely measured and compensated. With a single ion stored inside a high-finesse optical cavity, a cavity mode can be coherently coupled to the qubit transition.

Entanglement of trapped ions

We report on the scalable and deterministic generation and tomographic characterization of entangled states of up to 8 trapped ions and experiments towards entangling ions and photons.

ENTANGLEMENT OF TRAPPED IONS

We report on the scalable and deterministic generation and tomographic characterization of entangled states of up to 8 trapped ions and experiments towards entangling ions and photons.

From a Single-Photon Source to a Single-Ion Laser

A single Ca+ion is trapped in a high finesse cavity. Under continuous excitation, our single-ion device shows signatures of a quantum laser. Under pulsed excitation, it acts as an efficient source of single photons.

Precision measurement and calculation of the 3d /sup 2/D-level lifetimes of /sup 40/Ca+

Int this paper, a measurement technique based on deterministic coherent excitation to the D/sub 5/2/ state or incoherent shelving in the D/sub 3/2/ state is introduced, followed by a waiting period with free spontaneous decay and finally a measurement of the remaining excitation by high-efficiency quantum state detection.