Quantum error correction beyond qubits

Quantum computation and communication rely on the ability to manipulate quantum states robustly and with high fidelity. Thus, some form of error correction is needed to protect fragile quantum superposition states from corruption by so-called decoherence noise. Indeed, the discovery of quantum error correction (QEC) turned the field of quantum information from an academic curiosity into a developing technology. Here we present a continuous-variable experimental implementation of a QEC code, based upon entanglement among 9 optical beams. In principle, this 9-wavepacket adaptation of Shor's original 9-qubit scheme allows for full quantum error correction against an arbitrary single-beam (single-party) error.Comment: realization of a Gaussian error correction protocol suitable for non-Gaussian error correctio

Dynamics of the contact line in wetting and diffusing processes of water droplets on hydrogel (PAMPS–PAAM) substrates

International audienceWe studied the dynamics of the wetting and diffusing processes of water droplets on hydrogel (Poly(2-acrylamido-2-methyl-propane-sulfonic acid-co-acrylamide) (PAMPS-PAAM)) substrates. The profiles of the droplet and substrate were measured simultaneously using a grid projection method. We observed that as the water droplet diffuses into the gel, the contact line of the droplet exhibits successively two different behaviors: pinned and receding, and the transition between these two behaviors is closely related to the local deformation of the gel substrate. The contact line is pinned at an early stage. As the water diffusion proceeds, the contact angle of the droplet decreases while the angle of the local slope of the gel surface near the contact line increases. At the moment where these two angles almost correspond to each other, the contact line starts to recede. Our results indicate that due to the water diffusion, a locally swollen region is formed in the vicinity of the droplet-gel interface, and whether the contact line is pinned or recedes is determined by the surface property of this swollen region

Dynamics of spreading of liquid on a hydrogel substrate

International audienc

Dynamics of Liquid Contact Line on Visco-Elastic Gels

International audienc

Slow dynamics and intermittent quakes in soft glassy systems

We present measurements of the thermal fluctuations of the free surface of oil-in-water emulsions which exhibit a glassy behavior. The Surface Fluctuation Specular Reflection (SFSR) technique was applied to measure the free surface fluctuations. When the volume fraction of the oil droplets is close to or larger than the disordered packing volume fraction, the emulsion ages and its free surface exhibits abnormal fluctuations, consisting of rare but large amplitude quakes. From a statistical analysis of the signal, we observe that the relative importance of such intermittent quakes grows as the system ages. More precisely, we observe for the first time that the kurtosis of the fluctuations increases with aging time with an exponent of about 1.3. These quakes correspond to large changes in the local slope of the free surface over a few tenths of a second. We conjecture that such quakes reflect the dynamics peculiar to glassy systems driven by the relaxations of internal stress

Simple method to measure rheological properties of soft surfaces by a micro-needle contact

We developed a simple method to investigate rheological properties of soft surfaces, such as polymeric liquids and colloidal suspensions, by capturing the images of a metal micro-needle inserted into the surface. At contact, a meniscus-like deformation is formed on the surface. By relating the shape of the deformation to the balance of applied forces, local elasticity and viscosity just inside the surface are obtained. With a facile setup and rapid measurement process, the present method can be implemented to variety of systems, for instance, drying sessile drops and small volume of liquid confined in a capillary

Advancing liquid contact line on visco-elastic gel substrates: stick-slip vs. continuous motions

International audienceWe studied the dynamics of water sessile droplets advancing on hydrophobic and visco-elastic Poly(styrene-butadiene-styrene)(SBS)-paraffin gel substrates at various inflation rates. During the advancing process, the droplet contact line exhibits three different regimes of motions. When the contact line advances at a high velocity, the contact line moves continuously with a constant contact angle. As the contact line slows down, it starts stick-slip motion: the contact line is pinned at a certain position, then suddenly slips forward. With further decrease of the velocity, the contact line stops stick-slip and continuously advances again. The observed threshold values for the transitions of the contact line motions (continuous-stick-slip-continuous) indicate that the rheology of the gel drastically affects the dynamics of liquid on its surface. We suggest that on visco-elastic gels, the moving contact line exhibits both aspects of wetting on elastic solids and wetting on viscous liquids depending on the characteristic frequency of the gel surface deformation. At an intermediate regime, the stick-slip motion of the contact line appears. We also propose a simple geometrical model in the stick-slip regime which allows us to relate the jumps of droplet radius to the jumps of apparent contact angle