Quantum Relative Entropy of Tagging and Thermodynamics.

Thermodynamics establishes a relation between the work that can be obtained in a transformation of a physical system and its relative entropy with respect to the equilibrium state. It also describes how the bits of an informational reservoir can be traded for work using Heat Engines. Therefore, an indirect relation between the relative entropy and the informational bits is implied. From a different perspective, we define procedures to store information about the state of a physical system into a sequence of tagging qubits. Our labeling operations provide reversible ways of trading the relative entropy gained from the observation of a physical system for adequately initialized qubits, which are used to hold that information. After taking into account all the qubits involved, we reproduce the relations mentioned above between relative entropies of physical systems and the bits of information reservoirs. Some of them hold only under a restricted class of coding bases. The reason for it is that quantum states do not necessarily commute. However, we prove that it is always possible to find a basis (equivalent to the total angular momentum one) for which Thermodynamics and our labeling system yield the same relation.

Quantum Information Remote Carnot Engines and Voltage Transformers.

A physical system out of thermal equilibrium is a resource for obtaining useful work when a heat bath at some temperature is available. Information Heat Engines are the devices which generalize the Szilard cylinders and make use of the celebrated Maxwell demons to this end. In this paper, we consider a thermo-chemical reservoir of electrons which can be exchanged for entropy and work. Qubits are used as messengers between electron reservoirs to implement long-range voltage transformers with neither electrical nor magnetic interactions between the primary and secondary circuits. When they are at different temperatures, the transformers work according to Carnot cycles. A generalization is carried out to consider an electrical network where quantum techniques can furnish additional security.

Windowed defocused photographic speckle vibration measurement.

The out-of-plane vibration of a rough surface causes an in-plane vibration of its speckle pattern when observed with a defocused optical photographic system. If the frequency of the oscillations is high enough, a time-averaged specklegram is recorded from which the amplitude of the vibration can be estimated. The statistical character of speckle distributions along with the pixel sampling and intensity analog-to-digital conversion inherent to electronic cameras degrade the accuracy of the amplitude measurement to an extent that is analyzed and experimentally tested in this paper. The relations limiting the mutually competing metrological features of a defocused speckle system are also deduced mathematically.

Adaptive aperture defocused digital speckle photography.

Speckle photography can be used to monitor deformations of solid surfaces. Its measuring characteristics, such as range or lateral resolution, depend heavily on the optical recording and illumination setup. I show how, by the addition of two suitably perforated masks, the effective optical aperture of the system may vary from point to point of the surface, accordingly adapting the range and resolution to local requirements. Furthermore, by illuminating narrow areas, speckle size can be chosen independently from the optical aperture, thus lifting an important constraint on the choice of the latter. The technique, which I believe to be new, is described within the framework of digital defocused speckle photography under normal collimated illumination. Mutually limiting relations between the range of measurement and the spatial frequency resolution turn up both locally and when the whole surface under study is considered. They are deduced and discussed in detail. Finally, experimental results are presented.

Multiwindowed defocused electronic speckle photographic system for tilt measurement.

Defocused speckle photography has long been used to measure rotations of rough surfaces. By addition of a suitably perforated mask, some measurement properties, such as range and lateral resolution, may be changed at will. In particular, the maximum measurable tilt can be significantly increased, although at the expense of poorer lateral resolution. Advantages of this compared with previously described techniques include independent tuning of speckle size and optical system aperture and greater adaptability to various measuring needs. The benefits and disadvantages of the new and old techniques are thoroughly compared.