Electron beam X-Y deflection system Final report

Design and fabrication of electron beam X-Y deflection system for retrofit on welding gun

On The Origin of Super-Hot Electrons from Intense Laser Interactions with Solid Targets having Moderate Scale Length Preformed Plasmas

We use PIC modeling to identify the acceleration mechanism responsible for the observed generation of super-hot electrons in ultra-intense laser-plasma interactions with solid targets with pre-formed plasma. We identify several features of direct laser acceleration (DLA) that drive the generation of super-hot electrons. We find that, in this regime, electrons that become super-hot are primarily injected by a looping mechanism that we call loop-injected direct acceleration (LIDA)

Quantum data processing and error correction

This paper investigates properties of noisy quantum information channels. We define a new quantity called {\em coherent information} which measures the amount of quantum information conveyed in the noisy channel. This quantity can never be increased by quantum information processing, and it yields a simple necessary and sufficient condition for the existence of perfect quantum error correction.Comment: LaTeX, 20 page

Choi's Proof and Quantum Process Tomography

Quantum process tomography is a procedure by which an unknown quantum operation can be fully experimentally characterized. We reinterpret Choi's proof of the fact that any completely positive linear map has a Kraus representation [Lin. Alg. and App., 10, 1975] as a method for quantum process tomography. Furthermore, the analysis for obtaining the Kraus operators are particularly simple in this method.Comment: submitted to special issue of JMP on QI

HOLLOTRON switch for megawatt lightweight space inverters

The feasibility of satisfying the switching requirements for a megawatt ultralight inverter system using HOLLOTRON switch technology was determined. The existing experimental switch hardware was modified to investigate a coaxial HOLLOTRON switch configuration and the results were compared with those obtained for a modified linear HOLLOTRON configuration. It was concluded that scaling the HOLLOTRON switch to the current and voltage specifications required for a megawatt converter system is indeed feasible using a modified linear configuration. The experimental HOLLOTRON switch operated at parameters comparable to the scaled coaxial HOLLOTRON. However, the linear HOLLOTRON data verified the capability for meeting all the design objectives simultaneously including current density (greater than 2 A/sq cm), voltage (5 kV), switching frequency (20 kHz), switching time (300 ns), and forward voltage drop (less than or equal to 20 V). Scaling relations were determined and a preliminary design was completed for an engineering model linear HOLLOTRON switch to meet the megawatt converter system specifications

Black box search : framework and methods

A theoretical framework is constructed to analyze the behavior of all determin-istic non-repeating search algorithms as they apply to all possible functions of a given finite domain and range. A population table data structure is introduced for this purpose, and many properties of the framework are discovered, including the number of deterministic non-repeating search algorithms. Canonical forms are pre-sented for all elements of the framework, as well as methods for converting between the objects and their canonical numbers and back again. The theorems regarding population tables allow for a simple, alternate form of the No Free Lunch (NFL) theorem, an important theorem regarding search algorithm performance over all functions. Previously, this theorem has only been proven in overly-complicated, confusing fashion. Other statements of the NFL theorem are shown in the light of this framework and the theorem is extended to non-complete sets of functions and to a non-trivial definition of stochastic search. The framework allows for an extensive study of minimax distinctions between search algorithms. A change of representation is easily expressed in the framework with obvious performance im-plications. The expected performance of random search with replacement, random search without replacement, and enumeration will be studied in some detail. Claims in the field regarding search algorithm robustness will be tested empirically. Experiments were performed to determine how the compressibility of a function impacts its performance, with an emphasis on randomly selected functions. A genetic algorithm was run on two sets of functions: one set contained functions that were known to be compressible, and the other contained functions that had a high probability of being incompressible. Performance was found to be the same for both sets

Inequalities for quantum channels assisted by limited resources

The information capacities and ``distillability'' of a quantum channel are studied in the presence of auxiliary resources. These include prior entanglement shared between the sender and receiver and free classical bits of forward and backward communication. Inequalities and trade-off curves are derived. In particular an alternative proof is given that in the absence of feedback and shared entanglement, forward classical communication does not increase the quantum capacity of a channel.Comment: 8 pages, 4 figures (references updated, minor changes