Matthias Steiner

Single ion coupled to an optical fiber cavity.

We present the realization of a combined trapped-ion and optical cavity system, in which a single Yb(+) ion is confined by a micron-scale ion trap inside a 230 μm-long optical fiber cavity. We characterize the spatial ion-cavity coupling and measure the ion-cavity coupling strength using a cavity-stimulated Λ transition. Owing to the small mode volume of the fiber resonator, the coherent coupling strength between the ion and a single photon exceeds the natural decay rate of the dipole moment. This system can be integrated into ion-photon quantum networks and is a step towards cavity quantum electrodynamics based quantum information processing with trapped ions.

Direct Photonic Coupling of a Semiconductor Quantum Dot and a Trapped Ion

Coupling individual quantum systems lies at the heart of building scalable quantum networks. Here, we report the first direct photonic coupling between a semiconductor quantum dot and a trapped ion and we demonstrate that single photons generated by a quantum dot controllably change the internal state of a Yb^{+} ion. We ameliorate the effect of the 60-fold mismatch of the radiative linewidths with coherent photon generation and a high-finesse fiber-based optical cavity enhancing the coupling between the single photon and the ion. The transfer of information presented here via the classical correlations between the σ_{z} projection of the quantum-dot spin and the internal state of the ion provides a promising step towards quantum-state transfer in a hybrid photonic network.

Time-resolved scattering of a single photon by a single atom

We experimentally investigate the scattering of heralded photons from a single trapped atom and demonstrate that the atomic dynamics depend on whether the temporal envelope of the photon wave packet is exponentially decaying or rising.

Photon emission and absorption of a single ion coupled to an optical-fiber cavity.

We present a light-matter interface which consists of a single 174Yb+ ion coupled to an optical fiber cavity. We observe that photons at 935 nm are mainly emitted into the cavity mode and that correlations between the polarization of the photon and the spin state of the ion are preserved despite the intrinsic coupling into a single-mode fiber. Complementary, when a faint coherent light field is injected into the cavity mode, we find enhanced and polarization dependent absorption by the ion.

Polarization gradient cooling of single atoms in optical dipole traps

We experimentally investigate

Quantifying the role of thermal motion in free-space light-atom interaction

\sigma^+

Laser spectroscopy and cooling of Yb + ions on a deep-UV transition

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Photon bandwidth dependence of light-matter interaction

\sigma^-

Nonlinear photon-atom coupling in free space

polarization gradient cooling~(PGC) of a single

Single atoms coupled to a near-concentric cavity

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