Configurable unitary transformations and linear logic gates using quantum memories

We show that a set of optical memories can act as a configurable linear optical network operating on frequency-multiplexed optical states. Our protocol is applicable to any quantum memories that employ off-resonant Raman transitions to store optical information in atomic spins. In addition to the configurability, the protocol also offers favourable scaling with an increasing number of modes where N memories can be configured to implement an arbitrary N-mode unitary operations during storage and readout. We demonstrate the versatility of this protocol by showing an example where cascaded memories are used to implement a conditional CZ gate.Comment: 5 pages, 2 figure

Three decades of coastal subsidence in the slow-moving Nice Côte d'Azur Airport area (France) revealed by InSAR (interferometric synthetic-aperture radar): insights into the deformation mechanism

Coastal areas can be tremendously biodiverse and host a substantial part of the world's population and critical infrastructure. However, there are often fragile environments that face various hazards such as flooding, coastal erosion, land salinization or pollution, earthquake-induced land motion, or anthropogenic processes. In this article, we investigate the stability of the Nice Côte d'Azur Airport, which has been built on reclaimed land in the Var River delta (French Riviera, France). This infrastructure, as well as the ongoing subsidence of the airport runways, has been a permanent concern since the partial collapse of the platform in 1979. Here, we used the full archive of ESA SAR (synthetic-aperture radar) images from 1992 to 2020 to comprehensively monitor the dynamics of the airport subsidence. We found that the maximum downward motion rate has been slowing down from 16 mm yr−1 in the 1990s to 8 mm yr−1 today. However, sediment compaction is still active, and an acceleration phase of the continuous creep leading to a potential failure of a part of the platform cannot be excluded. Our study demonstrates the importance of remotely monitoring of the platform to better understand the motion of coastal land, which will ultimately help evaluate and reduce associated hazards.</p

Gradient echo quantum memory in warm atomic vapor

Video Article - http://www.jove.com/video/50552Gradient echo memory (GEM) is a protocol for storing optical quantum states of light in atomic ensembles. The primary motivation for such a technology is that quantum key distribution (QKD), which uses Heisenberg uncertainty to guarantee security of cryptographic keys, is limited in transmission distance. The development of a quantum repeater is a possible path to extend QKD range, but a repeater will need a quantum memory. In our experiments we use a gas of rubidium 87 vapor that is contained in a warm gas cell. This makes the scheme particularly simple. It is also a highly versatile scheme that enables in-memory refinement of the stored state, such as frequency shifting and bandwidth manipulation. The basis of the GEM protocol is to absorb the light into an ensemble of atoms that has been prepared in a magnetic field gradient. The reversal of this gradient leads to rephasing of the atomic polarization and thus recall of the stored optical state. We will outline how we prepare the atoms and this gradient and also describe some of the pitfalls that need to be avoided, in particular four-wave mixing, which can give rise to optical gain.Olivier Pinel, Mahdi Hosseini, Ben M. Sparkes, Jesse L. Everett, Daniel Higginbottom, Geoff T. Campbell, Ping Koy Lam, Ben C. Buchle

Variations à court terme des compartiments planctoniques d'un lac humique du Bouclier canadien

Les variations spatio-temporelles à court terme des compartiments planctoniques ont été étudiées simultanément du 30 juillet au 5 août 1986 dans un lac humique du Bouclier canadien. L'abondance du bactérioplancton fluctue de 1,4 à 1,7.106 cell. ml.-1 (coloration DAPI) ou de 2,7 à 7,7.106 cell. ml-1; (coloration Acridine Orange). La production du bactérioplancton estimée par incorporation de 3H méthyl thimidine, varie de 4 à 24.106 cell. l-1 h-1. Les valeurs d'activité hétérotrophe potentielle bactérienne estimée par assimilation de 14C glucose, s'échelonnent de 0,007 à 0,065 µg C.l-1. h-1. La biomasse pigmentaire (chlore. a et pheopigments) varie de 6,8 à 21,7 mg.m-3 . La production primaire est très faible (max. : 10 mg C. m-3 .h-1; 20 mg C.m-2 .h-1 ) et décroît très rapidement avec la profondeur (25 % à 82 % dans le premier mètre). Le microzooplancton (Rotifères, Bosmina, nauplies) représente plus de 90 % du peuplement zooplanctonique et les taux de broutage global du macrozooplancton sont faibles (25 % j-1). Les compartiments hétérotrophes prédominent dans le métabolisme du lac par rapport au compartiment autotrophe. Les patrons de variation spatiale reflètent la stratification verticale des compartiments et des processus autotrophes et hétérotrophes. Les maxima de photosynthèse, d'ATP et de production bactérienne se situent dans les eaux épilimnétiques tandis que les maxima d'abondance du bactérioptancton et des pigments se rencontrent dans l'hypolimnion. Le zooplancton est plus dense et broute d'avantage dans la strate 1-3 m. Ces variations spatiales semblent influencer l'activité hétérotrophe potentielle du bactérioptancton. Nos résultats montrent aussi des variations temporelles à court terme de la production primaire, de l'assimilation hétérotrophe et du broutage du macrozooplancton. Cette étude préliminaire met en lumière la nécessité de tenir compte des variations à court terme lors des études des relations trophodynamiques dans les écosystèmes planctoniques.Short term spatial and temporal variations in planktonic compartments were studied simultaneously, from July 30th to August 5th, 1986, in a humic lake on the Canadian Shield. Abundance of bacterioplankton ranged from 1,4 to 1,7 106 cell. ml-1 (DAP1) or from 2,7 to 7,7 106 cell. ml-1 (Acridine Orange). Bacterial production, as measured by incorporation of 3H methyl-thimidine, was estimated at 4-24 106 cells. l-1. h-1 and potential heterotrophic bacterial activity ranged from 0,007 to 0,065 µg C.l-1. h-1, as estimated by 14C glucose incorporation. Pigments biomass (chloro. a and phaeopigments) varied from 6,8 to 21,7 mg m-3. Primary production was low (max. : 10 mg C.m-3. h-1; 20 mg C.m-2. h-1) and decreased rapidly with depth (25-82 % in 1 m depth). Microzooplankton (rotifera, Bosmina, nauplii) accounted for more than 90 % of total numbers and macrozooplankton global grazing rates were low (25 % d-1). The heterotrophic compartments play a greater rate in the lake metabolism than the autotrophic compartment. Spatial variations reflect the stratification of the heterotrophic and autotrophic organisms and processes with depth. Maximum levels in primary production, ATP and bacterial production occur in epilimnetic waters, while maxima in bacterial numbers and algal pigments occur in the hypolimnion. Zooplancton density and macrozooplankton grazing rates were higher in the 1-3 m strata. These spatial patterns seem to influence the vertical profiles of the bacterial potential heterotrophic activity. Our results also show short term temporal variations in primary production, potential heterotrophic activity of bacterioplankton and macrozooplankton grazing rates. This preliminary study stresses the importance of short term variations in the assessment of the trophodynamics of the planktonic food wed

Fast Optimal Transport Averaging of Neuroimaging Data

Knowing how the Human brain is anatomically and functionally organized at the level of a group of healthy individuals or patients is the primary goal of neuroimaging research. Yet computing an average of brain imaging data defined over a voxel grid or a triangulation remains a challenge. Data are large, the geometry of the brain is complex and the between subjects variability leads to spatially or temporally non-overlapping effects of interest. To address the problem of variability, data are commonly smoothed before group linear averaging. In this work we build on ideas originally introduced by Kantorovich to propose a new algorithm that can average efficiently non-normalized data defined over arbitrary discrete domains using transportation metrics. We show how Kantorovich means can be linked to Wasserstein barycenters in order to take advantage of an entropic smoothing approach. It leads to a smooth convex optimization problem and an algorithm with strong convergence guarantees. We illustrate the versatility of this tool and its empirical behavior on functional neuroimaging data, functional MRI and magnetoencephalography (MEG) source estimates, defined on voxel grids and triangulations of the folded cortical surface.Comment: Information Processing in Medical Imaging (IPMI), Jun 2015, Isle of Skye, United Kingdom. Springer, 201

Quantum coherent control of highly multipartite continuous-variable entangled states by tailoring parametric interactions

The generation of continuous-variable multipartite entangled states is important for several protocols of quantum information processing and communication, such as one-way quantum computation or controlled dense coding. In this article we theoretically show that multimode optical parametric oscillators can produce a great variety of such states by an appropriate control of the parametric interaction, what we accomplish by tailoring either the spatio-temporal shape of the pump, or the geometry of the nonlinear medium. Specific examples involving currently available optical parametric oscillators are given, hence showing that our ideas are within reach of present technology.Comment: 14 pages, 5 figure

Fungal colonization in Cystic Fibrosis (CF): Epidemiology and antifungal resistance in a French cohort of CF patients – Focused on Aspergillus fumigatus colonization

Introduction: Cystic fibrosis (CF) is the major genetic inherited disease in the European Caucasian population, with an average of 1 in 3000 living births in France. Prognostic depend essentially on the lung impairments. While considerable attention therefore has been paid over recent decades to prevent and treat bacterial respiratory infections, we observed emergence of fungi colonization in CF respiratory tract. In particular, Aspergillus fumigatus represents the most common causative agent colonizing the airways of CF patients; it can be responsible for Allergic Bronchopulmonary Aspergillosis (ABPA). Since oral corticosteroids and itraconazole represent the mainstay of ABPA treatment, long-term therapy may increase the risk of acquired resistance to azoles that is mainly associated with amino acid substitutions in the CYP51A gene of A. fumigatus. Objective: First, we managed to have exhaustive epidemiological data on species of filamentous fungi able to colonize the airway tract of 300 CF patients followed-up in our national prospective study ("MucoFong" study – PHRC1902). Second, CF patients being chronically exposed to azole (especially to itraconazole), our study aimed to evaluate the prevalence of azole resistance in isolates prospectively collected from CF patients followed-up in seven French hospitals involved in our national prospective study. Third, we focused on the most prevalent species: Aspergillus fumigatus, studying the azole resistance at molecular level. To our knowledge, it is the first multicenter study focused on azole resistance of A. fumigatus in CF. Methods: A total of 243 sputa were analyzed using the same protocol in each centre. The MICs of antifungal drugs were evaluated for each isolate using the E-test ® strips. Focusing on A. fumigatus, a total of 87 isolates was collected in 85 patients. These isolates were characterized at the molecular level by targeting ITS, ß-tubulin and MAT-A/α genes. The CYP51A gene as well as its promoter was sequenced; a 3D Cyp51A protein homology model was built. Results and discussion: 300 patients were enrolled in this study. At inclusion time, most of them were adults colonized with A. fumigatus (about 35% of the patients). Scedosporium was isolated in 5%, and Exophiala in about 2%. Regarding antifungal susceptibility, isolates of Scedosporium and Exophiala exhibited antifungal resistance comparable with published data. Regarding A. fumigatus, a majority of isolates (88.1%) were found sensitive to itraconazole (MIC≤ 2μg/ml), and 2 new mutations were identified and localized within 3-dimensional Cyp51A protein model. To obtain insight into azole resistance of A. fumigatus, the results are analyzed taking into account clinical data, itraconazole exposition, and the potential correlation between the identified CYP5IA mutations and azole resistance is discussed based on the Cyp51A protein homology model