No abstract

No abstract

No abstract

We report on the formation of surface structures by photopolymerization of C60 and C70 in isotropic solutions. The structures show the same periodicity of the interference patterns used for photopolymerization and behave as diffraction gratings. Mass spectrometry confirmed that the deposited material contains polymerized fullerenes, while the structure of the deposit was investigated by atomic force microscopy. We have also shown that these periodic structures are useful for inducing mesophase orientation.

We present a proposal of a set-up to measure the work distribution of a process acting on a quantum system emulated by the transverse degrees of freedom of classical light. Hermite-Gaussian optical modes are used to represent the energy eigenstates of a quantum harmonic oscillator prepared in a thermal state. The Fourier transform of the work distribution, or the characteristic function, can be obtained by measuring the light intensity at the output of a properly designed interferometer. The usefulness of the approach is illustrated by calculating the work distribution for a unitary operation that displaces the linear momentum of the oscillator. Other types of processes and quantum systems can be implemented with the same scheme. We also show that the set-up can be used to investigate the energy distribution for open dynamics described by completely positive maps. We discuss the feasibility of the experiment, which can be realized with simple linear optical components.

No abstract

Light-sensitive media constitute a class of materials that are extensively studied because of their technological relevance for a variety of applications. In particular, the non-local reversible refractive index control by light, which is possible in substances exhibiting photorefractive properties, is of wide interest for real-time holography.[1] Photorefractivity is observed in photoconductors when a spacially non-uniform light exposure generates charge carriers which redistribute over macroscopic distances. This causes an electric field, which affects the refractive index of the material. Driven by the aim of obtaining low-cost and easily processable media, many efforts have been devoted to the understanding of the photorefractive properties of organic amorphous glasses [2±4] and polymers, [5±9] followed more recently by the interest in photorefractive liquid crystals. [10] Mesophases are attractive for photorefractivity because of their high spontaneous birefringence and the wide variety of field-induced refractive index control mechanisms.[11] The first liquid crystals studied for their photorefractive properties were bulk [12±14] and dispersed [15,16] nematic materials, but in the last years a number of investigations have showed that smectic phases can be photorefractive as well. [17±19] In particular, studies were carried out on chiral smectic A and C phases, where the mechanisms of field-induced fast molecular reorientation are connected with an induced or permanent polarization, respectively. [20] In all the reported investigations, the liquid-crystalline phase is not intrinsically photoconducting, so that the space±charge field set up is achieved either by dissolving a light sensitizer (and often a charge-transport agent as well) within its bulk, or by placing the mesophase within (like in dispersed systems), or between layers of, a photoconducting material. In this work the first example of a smectic mesophase that exhibits photorefractive behavior without any doping will be presented. It will also be shown that the observed photorefractive performance is larger than that previously reported for doped systems. Our approach is based on two recent results: the observation of photorefractivity in amorphous glasses formed by cyclopalladated complexes [21] and the synthesis of a new complex, with a closely related molecular structure, which exhibits a chiral smectic C phase. [22] The mesomorphic behavior of this complex, with a structure shown in Figure 1a and called for simplicity AzPdL, was investigated by optical microscopy, differential scanning calorimetry (DSC) and low-angle X-ray diffraction measurements. The observed transition temperatures between the isotropic (I), cholesteric (N*), chiral smectic C (SmC*) and crystalline (Cr) phases are included in Figure 1a.

The study of non-equilibrium physics from the perspective of the quantum limits of thermodynamics and fluctuation relations can be experimentally addressed with linear optical systems. We discuss recent experimental investigations in this scenario and present new proposed schemes and the potential advances they could bring to the field.