A single-photon transistor using nano-scale surface plasmons

It is well known that light quanta (photons) can interact with each other in nonlinear media, much like massive particles do, but in practice these interactions are usually very weak. Here we describe a novel approach to realize strong nonlinear interactions at the single-photon level. Our method makes use of recently demonstrated efficient coupling between individual optical emitters and tightly confined, propagating surface plasmon excitations on conducting nanowires. We show that this system can act as a nonlinear two-photon switch for incident photons propagating along the nanowire, which can be coherently controlled using quantum optical techniques. As a novel application, we discuss how the interaction can be tailored to create a single-photon transistor, where the presence or absence of a single incident photon in a ``gate'' field is sufficient to completely control the propagation of subsequent ``signal'' photons.Comment: 20 pages, 4 figure

Lakes beneath the ice sheet: The occurrence, analysis, and future exploration of Lake Vostok and other Antarctic subglacial lakes

Airborne geophysics has been used to identify more than 100 lakes beneath the ice sheets of Antarctica. The largest, Lake Vostok, is more than 250 km in length and 1 km deep. Subglacial lakes occur because the ice base is kept warm by geothermal heating, and generated meltwater collects in topographic hollows. For lake water to be in equilibrium with the ice sheet, its roof must slope ten times more than the ice sheet surface. This slope causes differential temperatures and melting/freezing rates across the lake ceiling, which excites water circulation. The exploration of subglacial lakes has two goals: to find and understand the life that may inhabit these unique environments and to measure the climate records that occur in sediments on lake floors. The technological developments required for in situ measurements mean, however, that direct studies of subglacial lakes may take several years to happen

Optimal operation point in 3D DCT-based lossy compression of color and multichannel remote sensing images

International audienc

Competition for co-operation: Roles and Realities in Russian Foreign Policy

The discursive reconstruction of Eurasia has brought about structural changes, which have strengthened Russia’s position internationally, and fortified its soft power. As such, the Eurasian project reflects Russia’s broader approach to parties including BRICS and the EU. Russia’s political elite routinely promotes specific conceptions of Russia’s international identity and role with different partners as a means to facilitate cooperation. This creates significant geographical and policy overlaps and breeds inconsistency and competition, but nonetheless contributes to Russia’s preferred low-cost, low-commitment version of co-operation. The Eurasian project therefore represents just one (albeit important) example of the Russian leadership’s conversion of ideas about the international arena into political realities. By balancing competing roles and relationships, Russia maintains a ‘multi-vector’ foreign policy that is flexible, unencumbered by restrictive alliances, and oriented towards sovereignty, great power and strength

Locally Adaptive DCT Filtering for Signal-Dependent Noise Removal

This work addresses the problem of signal-dependent noise removal in images. An adaptive nonlinear filtering approach in the orthogonal transform domain is proposed and analyzed for several typical noise environments in the DCT domain. Being applied locally, that is, within a window of small support, DCT is expected to approximate the Karhunen-Loeve decorrelating transform, which enables effective suppression of noise components. The detail preservation ability of the filter allowing not to destroy any useful content in images is especially emphasized and considered. A local adaptive DCT filtering for the two cases, when signal-dependent noise can be and cannot be mapped into additive uncorrelated noise with homomorphic transform, is formulated. Although the main issue is signal-dependent and pure multiplicative noise, the proposed filtering approach is also found to be competing with the state-of-the-art methods on pure additive noise corrupted images