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

On the impossibility of faithfully storing single-photons with the three-pulse photon echo

The three-pulse photon echo is a well-known technique to store intense light pulses in an inhomogeneously broadened atomic ensemble. This protocol is attractive because it is relatively simple and it is well suited for the storage of multiple temporal modes. Furthermore, it offers very long storage times, greater than the phase relaxation time. Here, we consider the three-pulse photon echo in both two- and three-level systems as a potential technique for the storage of light at the single-photon level. By explicit calculations, we show that the ratio between the echo signal corresponding to a single-photon input and the noise is smaller than one. This severely limits the achievable fidelity of the quantum state storage, making the three-pulse photon echo unsuitable for single-photon quantum memory.Comment: 6 pages, 4 figure

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

Traiter l'information avec des processeurs atomiques

Revue des protocoles de stockage quantique; Traitement classique de l'information sur porteuse optique; Comprendre les matériaux et leur interaction avec la lumière

Diffusion multiple coherente avec atomes froids de strontium: Effet de la saturation sur la retrodiffusion coherente - Piege magneto-optique sur raie etroite

In this thesis we have used a cloud of atomic strontium cooled on the 1S0 !1P1transition at 461nm in order to study the effects of coherent multiple scatteringas a function of saturation. We have observed a clear decrease of the enhancementfactor of the coherent backscattering cone as a function of saturation.We have then studied in detail the Doppler cooling in a 1d configuration onthis blue transition. It allowed us to highlight a supplementary diffusion phenomenonfor the momentum. It's due to local intensity imbalance within the beamprofil.The cloud have been finally transfered significantly to a magneto-optical trapon the 1S0 !3P1 intercombinaison line at 689nm . The goal is to increase thespatial density to observe the effects of photon localisation in this new regime.Dans cette th`ese, nous avons utilis´e un nuage d'atomes de strontium refroidispar laser sur la transition 1S0 !1 P1 `a 461nm afin d'´etudier les effets de diffusionmultiple coh´erente en fonction de la saturation. Nous avons observ´e uned´ecroissance nette du facteur d'amplification du cˆone de r´etrodiffusion coh´erenteen fonction de la saturation.Nous avons men´e ensuite une ´etude syst´ematique du refroidissement Dopplersur la transition bleue dans une configuration 1D. Ceci nous a permis demettre en ´evidence et de caract´eriser un ph´enom`ene de diffusion suppl´ementairepour l'impulsion, caus´e par des d´es´equilibres locaux dans le profil d'intensit´e desfaisceaux.Le nuage a enfin ´et´e transf´er´e significativement vers un pi`ege magn´eto-optiquesur la transition 1S0 !3P1 d'intercombinaison `a 689 nm. L'objectif ´etant d'augmenterla densit´e spatiale pour observer les effets de localisation des photons dansce nouveau r´egime

Diffusion multiple cohérente avec atomes froids de strontium (effet de la saturation sur la rétrodiffusion cohérente, piège magnéto-optique sur raie étroite)

Dans cette thèse, nous avons utilisé un nuage d'atomes de strontium refroidis par laser sur la transition 1S0 - 1P1 à 461nm afin d'étudier les effets de diffusion multiple cohérente en fonction de la saturation. Nous avons observé une décroissance nette du facteur d'amplification du cône de rétrodiffusion cohérente en fonction de la saturation. Nous avons mené ensuite une étude systématique du refroidissement Doppler sur la transition bleue dans une configuration 1D. Ceci nous a permis de mettre en évidence et de caractériser un phénomène de diffusion supplémentaire pour l'impulsion, causé par des déséquilibres locaux dans le profil d'intensité des faisceaux. Le nuage a enfin été transféré significativement vers un piège magnéto-optique sur la transition 1S0 - 3P1 d'intercombinaison à 689nm. L'objectif étant d'augmenter la densité spatiale pour observer les effets de localisation des photons dans ce nouveau régime.In this thesis we have used a cloud of atomic strontium cooled on the 1S0 - 1P1 transition at 461nm in order to study the effects of coherent multiple scattering as a function of saturation. We have observed a clear decrease of the enhancement factor of the coherent backscattering cone as a function of saturation. We have then studied in detail the Doppler cooling in a 1d configuration on this blue transition. It allowed us to highlight a supplementary diffusion phenomenon for the momentum. It's due to local intensity imbalance within the beam profil. The cloud have been finally transfered significantly to a magneto-optical trap on the 1S0 - 3P1 intercombinaison line at 689nm . The goal is to increase the spatial density to observe the effects of photon localisation in this new regime.NICE-BU Sciences (060882101) / SudocSudocFranceF

Photon echo with a few photons in two-level atoms

International audienc

Photon-echo quantum memory in solid state systems

Many applications of quantum communication crucially depend on reversible transfer of quantum states between light and matter. Motivated by rapid recent developments in theory and experiment, we review research related to quantum memory based on a photon-echo approach in solid state material with emphasis on use in a quantum repeater. After introducing quantum communication, the quantum repeater concept, and properties of a quantum memory required to be useful in a quantum repeater, we describe the historical development from spin echoes, discovered in 1950, to photon-echo quantum memory. We present a simple theoretical description of the ideal protocol, and comment on the impact of a non-ideal realization on its quantum nature. We extensively discuss rare-earth-ion doped crystals and glasses as material candidates, elaborate on traditional photon-echo experiments as a test-bed for quantum state storage, and describe the current state-of-the-art of photon-echo quantum memory. Finally, we give a brief outlook on current research