Quantal Density Functional Theory of Degenerate States

The treatment of degenerate states within Kohn-Sham density functional theory (KS-DFT) is a problem of longstanding interest. We propose a solution to this mapping from the interacting degenerate system to that of the noninteracting fermion model whereby the equivalent density and energy are obtained via the unifying physical framework of quantal density functional theory (Q-DFT). We describe the Q-DFT of \textit{both} ground and excited degenerate states, and for the cases of \textit{both} pure state and ensemble v-representable densities. This then further provides a rigorous physical interpretation of the density and bidensity energy functionals, and of their functional derivatives, of the corresponding KS-DFT. We conclude with examples of the mappings within Q-DFT.Comment: 10 pages. minor changes made. to appear in PR

Edge Electron Gas

The uniform electron gas, the traditional starting point for density-based many-body theories of inhomogeneous systems, is inappropriate near electronic edges. In its place we put forward the appropriate concept of the edge electron gas.Comment: 4 pages RevTex with 7 ps-figures included. Minor changes in title,text and figure

Precision laser range finder system design for Advanced Technology Laboratory applications

Preliminary system design of a pulsed precision ruby laser rangefinder system is presented which has a potential range resolution of 0.4 cm when atmospheric effects are negligible. The system being proposed for flight testing on the advanced technology laboratory (ATL) consists of a modelocked ruby laser transmitter, course and vernier rangefinder receivers, optical beacon retroreflector tracking system, and a network of ATL tracking retroreflectors. Performance calculations indicate that spacecraft to ground ranging accuracies of 1 to 2 cm are possible

Thr Erosion of Civilian Control of the Military in the United States Today

In over thirty-five years as a military historian, I have come to have great respect for and trust in American military officers. The United States is truly blessed to have men and women of the highest character leading its youth and safeguarding its security. That fact makes the present subject all the more troubling and unpleasant, whether to write or read about it. However, the subject is crucial to the nation’s security and to its survival as a republic. I am speaking of a tear in the nation’s civil and political fabric; my hope is that by bringing it to the attention of a wide military and defense readership I can prompt a frank, open discussion that could, by raising the awareness of the American public and alert- ing the armed forces, set in motion a process of healing

Quantum-Dot Cellular Automata using Buried Dopants

The use of buried dopants to construct quantum-dot cellular automata is investigated as an alternative to conventional electronic devices for information transport and elementary computation. This provides a limit in terms of miniaturisation for this type of system as each potential well is formed by a single dopant atom. As an example, phosphorous donors in silicon are found to have good energy level separation with incoherent switching times of the order of microseconds. However, we also illustrate the possibility of ultra-fast quantum coherent switching via adiabatic evolution. The switching speeds are numerically calculated and found to be 10's of picoseconds or less for a single cell. The effect of decoherence is also simulated in the form of a dephasing process and limits are estimated for operation with finite dephasing. The advantages and limitations of this scheme over the more conventional quantum-dot based scheme are discussed. The use of a buried donor cellular automata system is also discussed as an architecture for testing several aspects of buried donor based quantum computing schemes.Comment: Minor changes in response to referees comments. Improved section on scaling and added plot of incoherent switching time

Using the Military at Home: Yesterday, Today, and Tomorrow

Today the United States is undergoing a great transformation in national security thinking and priorities. Between the end of the Cold War in 1989 and the collapse of the Soviet Union in 1991, the country began to abandon the policy of containment and the strategy of deterrence that had governed American relations with the rest of the world for over four decades. For only the fourth time in its national history, the United States has been changing its national security policies and reconfiguring its military institutions to adapt to a new role in world politics. Once again, for a variety of reasons not least because of technologies Americans themselves pioneered, defense of the American homeland has become central to national security. Protecting the American people inside the United States is the most significant and perplexing of the changes underway in national defense. What should be-must be-the role of the military in homeland defense

Wholeness-Oneness

Perhaps we have a thing going in our church. In a memorable convention in Detroit four years ago our church acted in a most distinctive way. Aside from several bold administrative decisions, such as recognizing the autonomy of developing national churches overseas and creating a unified Board for Missions, our church collectively penned and proclaimed the total mission of the church in six brief resolutions and then summarized them in six concise but meaningful statements. We called them the Affirmations on God\u27s Mission

Hysteretic resistance spikes in quantum Hall ferromagnets without domains

We use spin-density-functional theory to study recently reported hysteretic magnetoresistance \rho_{xx} spikes in Mn-based 2D electron gases [Jaroszy\'{n}ski et al. Phys. Rev. Lett. (2002)]. We find hysteresis loops in our calculated Landau fan diagrams and total energies signaling quantum-Hall-ferromagnet phase transitions. Spin-dependent exchange-correlation effects are crucial to stabilize the relevant magnetic phases arising from distinct symmetry-broken excited- and ground-state solutions of the Kohn-Sham equations. Besides hysteretic spikes in \rho_{xx}, we predict hysteretic dips in the Hall resistance \rho_{xy}. Our theory, without domain walls, satisfactorily explains the recent data.Comment: 4 pages, 4 figures, published version (some changes to the text; same figures as in v1