We review the emerging field of organic spintronics, where organic materials are applied as a medium to transport and control spin-polarized signals. The contacts for injecting and detecting spins are formed by ferromagnetic metals, oxides, or inorganic semiconductors. First, the basic concepts of spintronics and organic electronics are addressed, and phenomena which are in particular relevant for organic spintronics are highlighted. Experiments using different organic materials, including carbon nanotubes, organic thin films, self-assembled monolayers and single molecules are then reviewed. Observed magnetoresistance points toward successful spin injection and detection, but spurious magnetoresistance effects can easily be confused with spin accumulation. A few studies report long spin relaxation times and lengths, which forms a promising basis for further research. We conclude with discussing outstanding questions and problems.

Electronic transport is localized in low-dimensional disordered media. The addition of gauge fields to disordered media leads to fundamental changes in the transport properties. We implement a synthetic gauge field for photons using silicon-on-insulator technology. By determining the distribution of transport properties, we confirm that waves are localized in the bulk and localization is suppressed in edge states. Our system provides a new platform for investigating the transport properties of photons in the presence of synthetic gauge fields.

We report the experimental observation of strong multifractality in wave functions below the Anderson localization transition in open three-dimensional elastic networks. Our results confirm the recently predicted symmetry of the multifractal exponents. We have discovered that the result of multifractal analysis of real data depends on the excitation scheme used in the experiment.PACS numbers: 72.15. Rn, 05.70.Jk, 42.25.Dd, 71.30.+h Critical phenomena are of prominent importance in condensed-matter physics. Criticality at the Anderson localization transition has been the subject of intensive theoretical research. Some important theoretical predictions have been made, among which is the remarkable aspect of multifractality of wave functions at this transition. Numerical simulations support these predictions but also raise more questions [1]. Recent experimental progress has paved the way for the direct investigation of the Anderson localization transition at the mobility edge in real samples [2,3,4].In this Letter, we report the experimental observation of strong multifractality (MF) just below the Anderson transition. This observation is based on the excitation of elastic waves in an open 3D disordered medium. The recently predicted symmetry relation of the MF exponents [5] is tested and confirmed. All results are compared with the corresponding analysis of diffusive (metallic) wave functions in the same network at a different frequency or with a light speckle pattern generated by a strongly scattering medium, showing a very clear difference between localizing and diffusive regimes. Our results not only highlight the presence of MF in wave functions close to the mobility edge, but also reveal new aspects of the MF character in real experimental systems.Before presenting the experimental results, we briefly review some general aspects of MF and their implications in the context of the Anderson transition. Multifractality quantifies the strong fluctuations of the wave function. It shows the non-trivial length-scale dependence of the moments of the intensity distribution. The dependence can be investigated by varying the system size L, or alternatively, if the system size is fixed, by dividing the system into small boxes of linear size b and varying b. This property is quantified by using the generalized Inverse Participation Ratios (gIPR)where I(r) is the normalized intensity (equal to |ψ 2 (r)|/ |ψ 2 (r)|d d r where ψ(r) is the wave function) and I Bi is the integrated probability inside a box B i of linear size b, with λ ≪ b ≪ L where λ is the wavelength. The summation is performed on the whole sample, which consists of n = (L/b) d boxes, and d is the space dimension. By definition P 1 ≡ 1 and P 0 ≡ n.At criticality, the ensemble averaged gIPR, P q , scales anomalously with the dimensionless scaling length L/b aswhere d(q − 1) and ∆ q are called the normal (Euclidean) and the anomalous dimensions, respectively. For a normal (extended) wave function, ∆ q = 0 for every q. A (single-) fractal wave function with f...

Many of the currently pursued experiments in quantum optics would greatly benefit from a strong interaction between light and matter. Here, we present a simple new scheme for the efficient coupling of single molecules and photons. A glass capillary with a diameter of 600 nm filled with an organic crystal tightly guides the excitation light and provides a maximum spontaneous emission coupling factor (β) of 18% for the dye molecules doped in the organic crystal. A combination of extinction, fluorescence excitation, and resonance fluorescence spectroscopy with microscopy provides high-resolution spatiospectral access to a very large number of single molecules in a linear geometry. We discuss strategies for exploring a range of quantum-optical phenomena, including polaritonic interactions in a mesoscopic ensemble of molecules mediated by a single mode of propagating photons.