Brownian motors Hänggi, P.; Marchesoni, F.; Nori, F.
Annalen der Physik,
02/2005, Letnik:
14, Številka:
1-3
Journal Article
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In systems possessing a spatial or dynamical symmetry breaking, thermal Brownian motion combined with unbiased, non‐equilibrium noise gives rise to a channelling of chance that can be used to ...exercise control over systems at the micro‐ and even on the nano‐scale. This theme is known as the “Brownian motor” concept. The constructive role of (the generally overdamped) Brownian motion is exemplified for a noise‐induced transport of particles within various set‐ups. We first present the working principles and characteristics with a proof‐of‐principle device, a diffusive temperature Brownian motor. Next, we consider very recent applications based on the phenomenon of signal mixing. The latter is particularly simple to implement experimentally in order to optimize and selectively control a rich variety of directed transport behaviors. The subtleties and also the potential for Brownian motors operating in the quantum regime are outlined and some state‐of‐the‐art applications, together with future roadways, are presented.
Transport of suspended Brownian particles dc driven along corrugated narrow channels is numerically investigated in the regime of finite damping. We show that inertial corrections cannot be neglected ...as long as the width of the channel bottlenecks is smaller than an appropriate particle diffusion length, which depends on the the channel corrugation and the drive intensity. With such a diffusion length being inversely proportional to the damping constant, transport through sufficiently narrow obstructions turns out to be always sensitive to the viscosity of the suspension fluid. The inertia corrections to the transport quantifiers, mobility, and diffusivity markedly differ for smoothly and sharply corrugated channels.
In this work comparison between the results of the first systems is a fixed solar and the second is the sun tracking in an attempt to increase the proportion of electricity production. Here a ...microcontroller (Arduino) and the light-dependent resistor (LDR) photo detector is used in this tracker. And then compare the results in different weather conditions and on different days to test the efficiency of the two systems. The efficiency of the tracking system is better than the fixed system by 12.3% on a sunny day and 4.9% on a partly cloudy day. However, it failed by 3.3% on a cloudy day. With a sunny day preference in the tracking system at 6.9% of partially cloudy days, and 12.1% with partially cloudy to a cloudy day. And verified from The efficiency of the work of the microcontroller (Arduino) system and the optical detector (LDR).
Background: The aim of this study was to evaluate the survival rate of patients with endocrine tumors of the pancreas, functioning or non-functioning, associated or not with MEN 1 syndrome. Patients ...and methods: Eighty-three patients with pancreatic endocrine tumors diagnosed in our department from 1978 to 2003 were studied. Results: The study included 37 men (44.6%) and 46 women (55.4%). The median age of patients at diagnosis was 55 years (range 19–81 years). Fifty-two patients (62.7%) had non-functioning endocrine tumors, 16 (19.3%) had functioning endocrine tumors and 15 (18.1%) had MEN 1 disease with pancreatic involvement. Twenty-seven patients (32.5%) had liver metastases at the time of diagnosis, involvement of the lymph nodes was found in 47 out of 79 patients (59.5%). Forty patients (48.2%) had radical surgery, 20 (24.1%) had palliative surgery and 53 were treated medically. The survival rate was significantly related to the presence of metastases, lymph node involvement, and the type of tumor and treatment. Conclusions: Tumor resection, the absence of liver and lymph node metastases, and the presence of MEN 1 syndrome are related to a better survival rate. Radical surgery continues to have a central role in the therapeutic approach to endocrine tumors of the pancreas.
We propose tunable chiral bound states in a system composed of superconducting giant atoms and a Josephson photonic-crystal waveguide (PCW), with no analog in other quantum setups. The chiral bound ...states arise due to interference in the nonlocal coupling of a giant atom to multiple points of the waveguide. The chirality can be tuned by changing either the atom-waveguide coupling or the external bias of the PCW. Furthermore, the chiral bound states can induce directional dipole-dipole interactions between multiple giant atoms coupling to the same waveguide. Our proposal is ready to be implemented in experiments with superconducting circuits, where it can be used as a tunable toolbox to realize topological phase transitions and quantum simulations.
We investigate the effects related to vortex-core deformations when vortices approach each other. As a result of these vortex-core deformations, the vortex-vortex interaction effectively acquires an ...attractive component leading to a variety of vortex patterns typical for systems with nonmonotonic repulsive-attractive interaction, such as stripes and labyrinths. The core deformations are anisotropic and can induce frustration in the vortex-vortex interaction. In turn, this frustration has an impact on the resulting vortex patterns, which are analyzed in the presence of additional random pinning, as a function of the pinning strength. This analysis can be applicable to vortices in multiband superconductors or to vortices in Bose-Einstein condensates.
In quantum-optics experiments with both natural and artificial atoms, the atoms are usually small enough that they can be approximated as pointlike compared to the wavelength of the electromagnetic ...radiation with which they interact. However, superconducting qubits coupled to a meandering transmission line, or to surface acoustic waves, can realize "giant artificial atoms" that couple to a bosonic field at several points which are wavelengths apart. Here, we study setups with multiple giant atoms coupled at multiple points to a one-dimensional (1D) waveguide. We show that the giant atoms can be protected from decohering through the waveguide, but still have exchange interactions mediated by the waveguide. Unlike in decoherence-free subspaces, here the entire multiatom Hilbert space (2^{N} states for N atoms) is protected from decoherence. This is not possible with "small" atoms. We further show how this decoherence-free interaction can be designed in setups with multiple atoms to implement, e.g., a 1D chain of atoms with nearest-neighbor couplings or a collection of atoms with all-to-all connectivity. This may have important applications in quantum simulation and quantum computing.
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