Detecting fractional Josephson effect through 4π4\pi phase slip

Fractional Josephson effect is a unique character of Majorana Fermions in topological superconductor system. This effect is very difficult to detect experimentally because of the disturbance of quasiparticle poisoning and unwanted couplings in the superconductor. Here, we propose a scheme to probe fractional DC Josephson effect of semiconductor nanowire-based topological Josephson junction through 4{\pi} phase slip. By exploiting a topological RF SQUID system we find that the dominant contribution for Josephson coupling comes from the interaction of Majorana Fermions, resulting the resonant tunneling with 4{\pi} phase slip. Our calculations with experimentally reachable parameters show that the time scale for detecting the phase slip is two orders of magnitude shorter than the poisoning time of nonequilibrium quasiparticles. Additionally, with a reasonable nanowire length the 4{\pi} phase slip could overwhelm the topological trivial 2{\pi} phase slip. Our work is meaningful for exploring the effect of modest quantum fluctuations of the phase of the superconductor on the topological system, and provide a new method for quantum information processing.Comment: 5 pages, 3 figure

Detecting fractional Josephson effect through 4π4\pi phase slip

Fractional Josephson effect is a unique character of Majorana Fermions in topological superconductor system. This effect is very difficult to detect experimentally because of the disturbance of quasiparticle poisoning and unwanted couplings in the superconductor. Here, we propose a scheme to probe fractional DC Josephson effect of semiconductor nanowire-based topological Josephson junction through 4{\pi} phase slip. By exploiting a topological RF SQUID system we find that the dominant contribution for Josephson coupling comes from the interaction of Majorana Fermions, resulting the resonant tunneling with 4{\pi} phase slip. Our calculations with experimentally reachable parameters show that the time scale for detecting the phase slip is two orders of magnitude shorter than the poisoning time of nonequilibrium quasiparticles. Additionally, with a reasonable nanowire length the 4{\pi} phase slip could overwhelm the topological trivial 2{\pi} phase slip. Our work is meaningful for exploring the effect of modest quantum fluctuations of the phase of the superconductor on the topological system, and provide a new method for quantum information processing.Comment: 5 pages, 3 figure

Learning a Dilated Residual Network for SAR Image Despeckling

In this paper, to break the limit of the traditional linear models for synthetic aperture radar (SAR) image despeckling, we propose a novel deep learning approach by learning a non-linear end-to-end mapping between the noisy and clean SAR images with a dilated residual network (SAR-DRN). SAR-DRN is based on dilated convolutions, which can both enlarge the receptive field and maintain the filter size and layer depth with a lightweight structure. In addition, skip connections and residual learning strategy are added to the despeckling model to maintain the image details and reduce the vanishing gradient problem. Compared with the traditional despeckling methods, the proposed method shows superior performance over the state-of-the-art methods on both quantitative and visual assessments, especially for strong speckle noise.Comment: 18 pages, 13 figures, 7 table

Orientation and Motion of Water Molecules at Air/Water Interface

Analysis of SFG vibrational spectra of OH stretching bands in four experimental configurations shows that orientational motion of water molecule at air/water interface is libratory within a limited angular range. This picture is significantly different from the previous conclusion that the interfacial water molecule orientation varies over a broad range within the vibrational relaxation time, the only direct experimental evidence for ultrafast and broad orientational motion of a liquid interface by Wei et al. [Phys. Rev. Lett. 86, 4799, (2001)] using single SFG experimental configuration

Special Purpose Pulsar Telescope for the Detection of Cosmic Gravitational Waves

Pulsars can be used to search for stochastic backgrounds of gravitational waves of cosmological origin within the very low frequency band (VLF), $10^{-7}$ to $10^{-9}$ Hz. We propose to construct a special 50 m radio telescope. Regular timing measurements of about 10 strong millisecond pulsars will perhaps allow the detection of gravitational waves within VLF or at least will give a more stringent upper limits.Comment: 5 pages, no figure, Latex fil

Research on the Rotary Ultrasonic Facing Milling of Ceramic Matrix Composites

AbstractCeramic matrix composites (CMC) has got increasing importance in many fields of industry, especially in the aerospace. However, due to the special properties, the conventional machining methods are generally very challenging for CMC. The rotary ultrasonic machining (RUM) is a high efficiency processing technology for these advanced materials. This paper carried out research on the rotary ultrasonic facing milling of C/SiC and developed the cutting force simulation software to optimize the cutting parameters. Verification experiments were conducted showing that the efficiency improved by RUM is 5.8 times while the surface quality is improved by 54.4% compared with the conventional milling