Single-photon-level optical storage in a solid-state spin-wave memory

A long-lived quantum memory is a firm requirement for implementing a quantum repeater scheme. Recent progress in solid-state rare-earth-ion-doped systems justifies their status as very strong candidates for such systems. Nonetheless an optical memory based on spin-wave storage at the single-photon-level has not been shown in such a system to date, which is crucial for achieving the long storage times required for quantum repeaters. In this letter we show that it is possible to execute a complete atomic frequency comb (AFC) scheme, including spin-wave storage, with weak coherent pulses of $\bar{n} = 2.5 \pm 0.6$ photons per pulse. We discuss in detail the experimental steps required to obtain this result and demonstrate the coherence of a stored time-bin pulse. We show a noise level of $(7.1 \pm 2.3)10^{-3}$ photons per mode during storage, this relatively low-noise level paves the way for future quantum optics experiments using spin-waves in rare-earth-doped crystals

Atomic frequency comb memory with spin wave storage in 153Eu3+:Y2SiO5

153Eu3+:Y2SiO5 is a very attractive candidate for a long lived, multimode quantum memory due to the long spin coherence time (~15 ms), the relatively large hyperfine splitting (100 MHz) and the narrow optical homogeneous linewidth (~100 Hz). Here we show an atomic frequency comb memory with spin wave storage in a promising material 153Eu3+:Y2SiO5, reaching storage times slightly beyond 10 {\mu}s. We analyze the efficiency of the storage process and discuss ways of improving it. We also measure the inhomogeneous spin linewidth of 153Eu3+:Y2SiO5, which we find to be 69 \pm 3 kHz. These results represent a further step towards realising a long lived multi mode solid state quantum memory.Comment: 7 pages and 7 figure

Quantum optical non-linearities induced by Rydberg-Rydberg interactions: a perturbative approach

In this article, we theoretically study the quantum statistical properties of the light transmitted through or reflected from an optical cavity, filled by an atomic medium with strong optical non-linearity induced by Rydberg-Rydberg van der Waals interactions. Atoms are driven on a two-photon transition from their ground state to a Rydberg level via an intermediate state by the combination of a weak signal field and a strong control beam. By using a perturbative approach, we get analytic results which remain valid in the regime of weak feeding fields, even when the intermediate state becomes resonant. Therefore they allow us to investigate quantitatively new features associated with the resonant behaviour of the system. We also propose an effective non-linear three-boson model of the system which, in addition to leading to the same analytic results as the original problem, sheds light on the physical processes at work in the system

Variational calculations of the Λ\Lambda-seperation energy of the Λ17_{\Lambda}^{17}O hypernucleus

Variational Monte Carlo calculations have been made for the $_{ \Lambda}^{17}$O hypernucleus using realistic two- and three-baryon interactions. A two pion exchange potential with spin- and space-exchange components is used for the $\Lambda$N potential. Three-body two-pion exchange and strongly repulsive dispersive $\Lambda$NN interactions are also included. The trial wave function is constructed from pair- and triplet-correlation operators acting on a single particle determinant. These operators consist of central, spin, isospin, tensor and three- baryon potential components. A cluster Monte Carlo method is developed for noncentral correlations and is used with up to four-baryon clusters in our calculations. The three-baryon $\Lambda$NN force is discussed.Comment: 24 pages, 2 figs available by fax., for publication in Phys. Rev.

Phenomenological Lambda-Nuclear Interactions

Variational Monte Carlo calculations for ${_{\Lambda}^4}H$ (ground and excited states) and ${_{\Lambda}^5}He$ are performed to decipher information on ${\Lambda}$-nuclear interactions. Appropriate operatorial nuclear and ${\Lambda}$-nuclear correlations have been incorporated to minimize the expectation values of the energies. We use the Argonne $\upsilon_{18}$ two-body NN along with the Urbana IX three-body NNN interactions. The study demonstrates that a large part of the splitting energy in ${_{\Lambda}^4}H$ ($0^+-1^+$) is due to the three-body ${\Lambda}$ NN forces. $_{\Lambda}^{17}O$ hypernucleus is analyzed using the {\it s}-shell results. $\Lambda$ binding to nuclear matter is calculated within the variational framework using the Fermi-Hypernetted-Chain technique. There is a need to correctly incorporate the three-body ${\Lambda}$ NN correlations for $\Lambda$ binding to nuclear matter.Comment: 18 pages (TeX), 2 figure

Predicting Lung Deposition of Extrafine Inhaled Corticosteroid-Containing Fixed Combinations in Patients with Chronic Obstructive Pulmonary Disease Using Functional Respiratory Imaging: An in Silico Study

Background: Functional respiratory imaging (FRI) is a computational fluid dynamics-based technique using three-dimensional models of human lungs and formulation profiles to simulate aerosol deposition. Methods: FRI was used to evaluate lung deposition of extrafine beclomethasone dipropionate (BDP)/formoterol fumarate (FF)/glycopyrronium bromide (GB) and extrafine BDP/FF delivered through pressurized metered dose inhalers and to compare results with reference gamma scintigraphy data. FRI combined high-resolution computed tomography scans of 20 patients with moderate-to-severe chronic obstructive pulmonary disease (mean forced expiratory volume in 1 second 42% predicted) with in silico computational flow simulations, and incorporated drug delivery parameters to calculate aerosol airway deposition. Inhalation was simulated using profiles obtained from real-life measurements. Results: Total lung deposition (proportion deposited in intrathoracic region) was similarly high for both products, with mean ± standard deviation (SD) values of 31.0% ± 5.7% and 28.1% ± 5.2% (relative to nominal dose) for BDP/FF/GB and BDP/FF, respectively. Pairwise comparison of the deposition of BDP and FF gave a mean intrathoracic BDP/FF/GB:BDP/FF deposition ratio of 1.10 (p = 0.0405). Mean intrathoracic, central and peripheral deposition ratios for BDP were 1.09 (95% confidence interval [CI]: 1.05-1.14), 0.92 (95% CI: 0.89-0.96), and 1.20 (95% CI: 1.15-1.26), respectively, and for FF were 1.11 (95% CI: 1.07-1.15), 0.94 (95% CI: 0.91-0.98), and 1.21 (95% CI: 1.15-1.27), within the bioequivalence range (0.80-1.25) for intrathoracic and central regions, and slightly exceeding the upper boundary in the peripheral region. Mean ± SD central:peripheral deposition (C:P) was 0.48 ± 0.13 for BDP/FF/GB and 0.62 ± 0.17 for BDP/FF, indicating a higher proportion of drug deposition in the small airways than in the large airways. Conclusion: FRI demonstrated similar deposition patterns for extrafine BDP/FF/GB and BDP/FF, with both having a high lung deposition. Moreover, the deposition patterns of BDP and FF were similar in both products. Furthermore, the C:P ratios of both products indicated a high peripheral deposition, supporting small airway targeting and delivery of these two extrafine fixed combinations, with a small difference in ratios potentially due to mass median aerodynamic diameters

Multiscale Modeling of a Nanoelectromechanical Shuttle

In this article, we report a theoretical analysis of a nanoelectromechanical shuttle based on a multiscale model that combines microscopic electronic structure data with macroscopic dynamics. The microscopic part utilizes a (static) density functional description to obtain the energy levels and orbitals of the shuttling particle together with the forces acting on the particle. The macroscopic part combines stochastic charge dynamics that incorporates the microscopically evaluated tunneling rates with a Newtonian dynamics. We have applied the multiscale model to describe the shuttling of a single copper atom between two gold-like jellium electrodes. We find that energy spectrum and particle surface interaction greatly influence shuttling dynamics; in the specific example that we studied the shuttling is found to involve only charge states Q=0 and Q=+e. The system is found to exhibit two quasi-stable shuttling modes, a fundamental one and an excited one with a larger amplitude of mechanical motion, with random transitions between them.Comment: 9 pages, 9 figure