Quantum memory for light: large efficiency at telecom wavelength

We implement the ROSE protocol in an erbium doped solid, compatible with the telecom range. The ROSE scheme is an adaptation of the standard 2-pulse photon echo to make it suitable for a quantum memory. We observe an efficiency of 40% in a forward direction by using specific orientations of the light polarizations, magnetic field and crystal axes

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 Land\'e $g$-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.Comment: 5 pages, 4 figures, supplementary material (3 pages

Optical memory bandwidth and multiplexing capacity in the erbium telecommunication window

We study the bandwidth and multiplexing capacity of an erbium-doped optical memory for quantum storage purposes. We concentrate on the protocol ROSE (Revival of a Silenced Echo) because it has the largest potential multiplexing capacity. Our analysis is applicable to other protocols that involve strong optical excitation. We show that the memory performance is limited by instantaneous spectral diffusion and we describe how this effect can be minimised to achieve optimal performance

Interlaced spin grating for optical wave filtering

Interlaced Spin Grating is a scheme for the preparation of spectro-spatial periodic absorption gratings in a inhomogeneously broadened absorption profile. It relies on the optical pumping of atoms in a nearby long-lived ground state sublevel. The scheme takes advantage of the sublevel proximity to build large contrast gratings with unlimited bandwidth and preserved average optical depth. It is particularly suited to Tm-doped crystals in the context of classical and quantum signal processing. In this paper, we study the optical pumping dynamics at play in an Interlaced Spin Grating and describe the corresponding absorption profile shape in an optically thick atomic ensemble. We show that, in Tm:YAG, the diffraction efficiency of such a grating can reach 18.3% in the small angle, and 11.6% in the large angle configuration when the excitation is made of simple pulse pairs, considerably outperforming conventional gratings.Comment: 11 pages, 13 figures in Physical Review A, 201

Time reversal of light by linear dispersive filtering near atomic resonance

Based on the similarity of paraxial diffraction and dispersion mathematical descriptions, the temporal imaging of optical pulses combines linear dispersive filters and quadratic phase modulations operating as time lenses. We consider programming a dispersive filter near atomic resonance in rare earth ion doped crystals, which leads to unprecedented high values of dispersive power. This filter is used in an approximate imaging scheme, combining a single time lens and a single dispersive section and operating as a time reversing device, with potential applications in radio-frequency signal processing. This scheme is closely related to three-pulse photon echo with chirped pulses but the connection with temporal imaging and dispersive filtering emphasizes new features.Comment: 21 pages, 11 figure

Optical Excitation of Nuclear Spin Coherence in Tm3+:YAG

A thulium-doped crystal is experimentally shown to be an excellent candidate for broadband quantum storage in a solid-state medium. For the first time, nuclear spin coherence is optically excited, detected and characterized in such a crystal. The lifetime of the spin coherence -- the potential storage entity -- is measured by means of Raman echo to be about 300 $\mu$s over a wide range of ground state splittings. This flexibility, attractive for broadband operation, and well fitted to existing quantum sources, results from the simple hyperfine structure, contrasting with Pr- and Eu- doped crystals

Optical Excitation of Nuclear Spin Coherence in Tm3+:YAG

A thulium-doped crystal is experimentally shown to be an excellent candidate for broadband quantum storage in a solid-state medium. For the first time, nuclear spin coherence is optically excited, detected and characterized in such a crystal. The lifetime of the spin coherence -- the potential storage entity -- is measured by means of Raman echo to be about 300 $\mu$s over a wide range of ground state splittings. This flexibility, attractive for broadband operation, and well fitted to existing quantum sources, results from the simple hyperfine structure, contrasting with Pr- and Eu- doped crystals

Stimulated Raman adiabatic passage in Tm3+:YAG

International audienceWe report on the experimental demonstration of stimulated Raman adiabatic passage in a Tm 3+ : YAG crystal. Tm 3+ : YAG is a promising material for use in quantum information processing applications, but as yet there are few experimental investigations of coherent Raman processes in this material. We investigate the effect of inhomogeneous broadening and Rabi frequency on the transfer efficiency and the width of the two-photon spectrum. Simulations of the complete Tm 3+ : YAG system are presented along with the corresponding experimental results

Adiabatic passage with spin locking in Tm3+:YAG

International audienceIn low-concentration Tm 3+ :YAG, we observe efficient adiabatic rapid passage (ARP) of thulium nuclear spin over flipping times much longer than T 2. Efficient ARP with long flipping time has been observed in monoatomic solids for decades and has been analyzed in terms of spin temperature and of the thermodynamic equilibrium of a coupled spin ensemble. In low-concentration impurity-doped crystals the spin temperature concept may be questioned. A single spin model should be preferred since the impurity ions are weakly coupled together but interact with the numerous off-resonant matrix ions that originate the spin-spin relaxation. The experiment takes place in the context of quantum information investigation, involving impurity-doped crystals, spin hyperpolarization by optical pumping, and optical detection of the spin evolution

20 GHz instantaneous bandwidth RF spectrum analyzer with high time-resolution

International audienceWe report on the experimental demonstration of a multi-gigahertz bandwidth RF spectrum analyzer exhibiting a resolution below 20 MHz, based on spectral hole burning in a rare-earth ion-doped crystal. To be compatible with demanding real-time spectrum monitoring applications, our demonstrator is designed to reach a high time resolution. For this purpose, we implemented the so-called "rainbow" architecture in which the spectral components of the incoming signal are angularly separated by the crystal, and are then acquired with a pixelated photodetector. The Tm 3+ :YAG crystal is programmed with a semiconductor DFB laser which frequency scan is servo-controlled and synchronized with the angular scan of a resonant galvanometric mirror, while a high-speed camera is used to acquire the spectra. In the perspective of future implementation within a system, the crystal is cooled below 4 K with a closed-cycle cryostat. With this setup, we have been able to monitor and record the spectrum of complex microwave signals over an instantaneous bandwidth above 20 GHz, with a time resolution below 100 µs, 400 resolvable frequency components and a probability of intercept of 100 %