In non-abelian gauge theories without matter fields, expectation values of large Wilson loops and loop correlation functions are difficult to compute through numerical simulation, because the signal-to-noise ratio is very rapidly decaying for increasing loop sizes. Using a multilevel scheme that exploits the locality of the theory, we show that the statistical errors in such calculations can be exponentially reduced. We explicitly demonstrate this in the SU(3) theory, for the case of the Polyakov loop correlation function, where the efficiency of the simulation is improved by many orders of magnitude when the area bounded by the loops exceeds 1 fm 2 .

For the first time, the incorporation of interface passivation structures in ultrathin Cu(In,Ga)Se2 (CIGS) based solar cells is shown in a flexible lightweight stainless-steel substrate. The fabrication was based on an industry scalable lithography technique - nanoimprint lithography (NIL) - for a 15x15 cm2 dielectric layer patterning, needed to reduce optoelectronic losses at the rear interface. The nanopatterning schemes are usually developed by lithographic techniques or by processes with limited scalability and reproducibility (nanoparticle lift-off, spin-coating, etc). However, in this work the dielectric layer is patterned using NIL, a low cost, large area, high resolution, and high throughput technique. To assess the NIL performance, devices with a NIL nanopatterned dielectric layer are benchmarked against electron-beam lithography (EBL) patterning, using rigid substrates. Up to now, EBL is considered the most reliable technique for patterning laboratory samples. The device patterned by NIL shows similar light to power conversion efficiency average values compared to the EBL patterned device - 12.6 % vs 12.3 %, respectively - highlighting the NIL potential for application in the solar cell sector. Moreover, the impact of the lithographic processes, such as different etch by-products, in the rigid solar cells’ figures of merit were evaluated from an elemental point of view via X-ray Photoelectron Spectroscopy and electrically through a Solar Cell Capacitance Simulator (SCAPS) fitting procedure. After an optimised NIL process, the device on stainless-steel achieved an average power conversion efficiency value of 11.7 % - a slightly lower value than the one obtained for the rigid approach, due to additional challenges raised by processing and handling steel substrates, even though scanning transmission electron microscopy did not show any clear evidence of impurity diffusion towards the absorber. Notwithstanding, time-resolved photoluminescence results strongly suggested the presence of additional non-radiative recombination mechanisms in the stainless-steel absorber, which were not detected in the rigid solar cells, and are compatible with elemental diffusion from the substrate. Nevertheless, bending tests on the stainless-steel device demonstrated the mechanical stability of the CIGS-based device up to 500 bending cycles.

This work provides an experimental characterization and equivalent circuit modelling of electrochemically gated field effect transistors (EGFETs) using a graphene layer. The aim is to demonstrate the detection limit of these sensing devices for bioelectronics applications. Towards that, we present a detail study of the; (i) sources of intrinsic noise, (ii) the effect of ionic density in charge transfer resistance and (iii) the existence of parasitic conducting paths in the surrounding electrolyte. To investigate the liquid-based applications of graphene based EGFETs, quantifying the basic physical properties of graphene/solution interface is crucial. Towards that, we present a detail study of zero bias charge transfer resistance by using different type of ionic solutions and cell culture mediums. Measurements of the electrical noise were also performed to determine the EGFET detection limit. The performance of the EGFET to record the electrophysiological signals was evaluated using adult zebra fish heart and electrogenic cell cultures. The electrocardiogram of the zebrafish heart was monitored with signal-to-noise-ratio higher than 7. This contribution also discusses the application of graphene based EGFETS to measure electrophysiological signals in cell cultures. For instance, ultra-week extracellular signals resulting from cell metabolic activity or low frequency calcium waves. Keywords. Graphene, electrochemically gated field effect transistor, charge transport, intrinsic noise, extracellular signals. Figure 1