Experimentally realizable quantum comparison of coherent states and its applications

When comparing quantum states to each other, it is possible to obtain an unambiguous answer, indicating that the states are definitely different, already after a single measurement. In this paper we investigate comparison of coherent states, which is the simplest example of quantum state comparison for continuous variables. The method we present has a high success probability, and is experimentally feasible to realize as the only required components are beam splitters and photon detectors. An easily realizable method for quantum state comparison could be important for real applications. As examples of such applications we present a "lock and key" scheme and a simple scheme for quantum public key distribution.Comment: 14 pages, 5 figures, version one submitted to PRA. Version two is the final accepted versio

Frequency and fundamental signal measurement algorithms for distributed control and protection applications

Increasing penetration of distributed generation within electricity networks leads to the requirement for cheap, integrated, protection and control systems. To minimise cost, algorithms for the measurement of AC voltage and current waveforms can be implemented on a single microcontroller, which also carries out other protection and control tasks, including communication and data logging. This limits the frame rate of the major algorithms, although analogue to digital converters (ADCs) can be oversampled using peripheral control processors on suitable microcontrollers. Measurement algorithms also have to be tolerant of poor power quality, which may arise within grid-connected or islanded (e.g. emergency, battlefield or marine) power system scenarios. This study presents a 'Clarke-FLL hybrid' architecture, which combines a three-phase Clarke transformation measurement with a frequency-locked loop (FLL). This hybrid contains suitable algorithms for the measurement of frequency, amplitude and phase within dynamic three-phase AC power systems. The Clarke-FLL hybrid is shown to be robust and accurate, with harmonic content up to and above 28% total harmonic distortion (THD), and with the major algorithms executing at only 500 samples per second. This is achieved by careful optimisation and cascaded use of exact-time averaging techniques, which prove to be useful at all stages of the measurements: from DC bias removal through low-sample-rate Fourier analysis to sub-harmonic ripple removal. Platform-independent algorithms for three-phase nodal power flow analysis are benchmarked on three processors, including the Infineon TC1796 microcontroller, on which only 10% of the 2000 mus frame time is required, leaving the remainder free for other algorithms

Path allocation in a three-stage broadband switch with intermediate channel grouping

A method for path allocation for use with three-stage ATM switches that feature multiple channels between the switch modules in adjacent stages is described. The method is suited to hardware implementation using parallelism to achieve a very short execution time. This allows path allocation to be performed anew in each time slot. A detailed description of the necessary hardware is presented. This hardware counts the number of cells requesting each output module, allocates a path through the intermediate stage of the switch to each cell, and generates a routing tag for each cell, indicating the path assigned to i

Skein theory for the ADE planar algebras

We give generators and relations for the planar algebras corresponding to $ADE$ subfactors. We also give a basis and an algorithm to express an arbitrary diagram as a linear combination of these basis diagrams

Green fluorescent protein as an indicator of cryoinjury in tissues.

The fluorescence intensity of Green Fluorescent Protein (GFP) has previously been demonstrated to be an accurate indicator of cellular viability following cryoinsult in individual GFP-transfected cells. In an attempt to ascertain whether GFP fluorescence intensity may also be used as a viability indicator following cryogenic insults in whole tissues, this study examines the transient fluorescence intensity of GFP-transfected mouse hepatic tissue ex vivo following cryoinsult. The observed trends are compared with diffusion-based models. It was observed that the fluorescence intensity of the exposed tissues exhibited slow exponential decay, while the solution in which the tissues were placed inversely gained fluorescence. This slow decay (~3 h) is in contrast to the rapidly diminished fluorescence intensity (seconds) seen in GFP-cell cultures following cryoinsult. These trends suggest that mass diffusion of GFP in the interstitial space, and ultimately into the surrounding medium, is the primary mechanism which determines the fluorescence loss in cryoinjured tissues. These results suggest GFP-transfected tissues may be effectively used as indicators of cryoinjury, and hence viability, following hypothermal insult provided that a sufficiently long incubation is held before observation. It was found that a meaningful observation (15% reduction in fluorescence) could be made three hours subsequent to cryoinjury for the tissues used in this study