Strain-mediated ion-ion interaction in rare-earth-doped solids.

It was recently shown that the optical excitation of rare-earth ions produces a local change of the host matrix shape, attributed to a change of the rare-earth ion's electronic orbital geometry. In this work we investigate the consequences of this piezo-orbital backaction and show from a macroscopic model how it yields a disregarded ion-ion interaction mediated by mechanical strain. This interaction scales as1/r3, similarly to the other archetypal ion-ion interactions, namely electric and magnetic dipole-dipole interactions. We quantitatively assess and compare the magnitude of these three interactions from the angle of the instantaneous spectral diffusion mechanism, and re-examine the scientific literature in a range of rare-earth doped systems in the light of this generally underestimated contribution.

Two-pulse photon echo area theorem in an optically dense medium.

We perform a theoretical and experimental study of the two-pulse photon echo area conservation law in an optically dense medium. The experimental properties of the echo signal are studied at 4K on the optical transition  3H 6(1)→3H 4(1) (793 nm) of Tm 3+ in a YAG crystal for a wide range of pulse areas of the two incoming light pulses, up to θ 1 r o x4π and θ 2≈7π respectively, with optical depth 1.5. We analyze the experimental data by using the analytic solution of the photon echo area theorem for plane waves. We find that the transverse Gaussian spatial profile of the beam leads to an attenuation of the echo area nutation as function of θ1 and θ2. Additional spatial filtering of the photon echo beam allows to recover this nutation. The experimental data are in good agreement with the solution of photon echo pulse area theorem for weak incoming pulse areas θ 1,2≲π. However at higher pulse areas, the observations diverge from the analytic solution requiring further theoretical and experimental studies.

Selective Optical Addressing of Nuclear Spins through Superhyperfine Interaction in Rare-Earth Doped Solids.

In Er^{3+}:Y_{2}SiO_{5}, we demonstrate the selective optical addressing of the ^{89}Y^{3+} nuclear spins through their superhyperfine coupling with the Er^{3+} electronic spins possessing large Landé g factors. We experimentally probe the electron-nuclear spin mixing with photon echo techniques and validate our model. The site-selective optical addressing of the Y^{3+} nuclear spins is designed by adjusting the magnetic field strength and orientation. This constitutes an important step towards the realization of long-lived solid-state qubits optically addressed by telecom photons.

Time reversal of optically carried radiofrequency signals in the microsecond range.

The time-reversal (TR) protocol we implement in an erbium-doped YSO crystal is based on photon echoes but avoids the storage of the signal to be processed. Unlike other approaches implying digitizing or highly dispersive optical fibers, the proposed scheme reaches the µs range and potentially offers high bandwidth, both required for RADAR applications. In this Letter, we demonstrate faithful reversal of arbitrary pulse sequences with 6 µs duration and 10 MHz bandwidth. To the best of our knowledge, this is the first demonstration of TR via linear filtering in a programmable material.