The study of quantum correlations in solid state systems is a large avenue for research and their detection and manipulation are an actual challenge to overcome. In this context, we show by using first-principles calculations on the prototype material KNaCuSi4O10 that the degree of quantum correlations in this spin cluster system can be managed by external hydrostatic pressure. Our results open the doors for research in detection and manipulation of quantum correlations in magnetic systems with promising applications in quantum information science.

The thermal diffusivity and thermal conductivity have been determined for lead iodide PbI2, at room temperature, using the photoacoustic spectroscopy. The result shows a thermal diffusivity αs=(25.0±0.4)×10−3 cm2/s, a value very close to other semiconductors of current technological importance. The electrical conductivity is also measured and discussed.

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A system for imaging magnetic surfaces using a magnetoresistive sensor array is developed. The experimental setup is composed of a linear array of 12 sensors uniformly spaced, with sensitivity of 150 pT*Hz(-1/2) at 1 Hz, and it is able to scan an area of (16 × 18) cm(2) from a separation of 0.8 cm of the sources with a resolution of 0.3 cm. Moreover, the point spread function of the multi-sensor system is also studied, in order to characterize its transference function and to improve the quality in the restoration of images. Furthermore, the images are generated by mapping the response of the sensors due to the presence of phantoms constructed of iron oxide, which are magnetized by a pulse of 80 mT. The magnetized phantoms are linearly scanned through the sensor array and the remanent magnetic field is acquired and displayed in gray levels using a PC. The images of the magnetic sources are reconstructed using two-dimensional generalized parametric Wiener filtering. Our results exhibit a very good capability to determine the spatial distribution of magnetic field sources, which produce magnetic fields of low intensity.