Securing coherence rephasing with a pair of adiabatic rapid passages

Coherence rephasing is an essential step in quantum storage protocols that use echo-based strategies. We present a thorough analysis on how two adiabatic rapid passages (ARP) are able to rephase atomic coherences in an inhomogeneously broadened ensemble. We consider both the cases of optical and spin coherences, rephased by optical or radio-frequency (rf) ARPs, respectively. We show how a rephasing sequence consisting of two ARPs in a double-echo scheme is equivalent to the identity operator (any state can be recovered), as long as certain conditions are fulfilled. Our mathematical treatment of the ARPs leads to a very simple geometrical interpretation within the Bloch sphere that permits a visual comprehension of the rephasing process. We also identify the conditions that ensure the rephasing, finding that the phase of the optical or rf ARP fields plays a key role in the capability of the sequence to preserve the phase of the superposition state. This settles a difference between optical and rf ARPs, since field phase control is not readily guaranteed in the former case. We also provide a quantitative comparison between $\pi$-pulse and ARP rephasing efficiencies, showing the superiority of the latter. We experimentally verify the conclusions of our analysis through rf ARP rephasing sequencies performed on the rare-earth ion-doped crystal Tm$^{3+}$:YAG, of interest in quantum memories.Comment: 24 pages, 7 figure

Fighting to Save a Nation: Volunteerism and London’s Auxiliary Fire Service in the Blitz

The London Blitz of 1940 is one of the most horrifying events of World War 2. For the first time, citizens were the primary target in an attempt to shock Britain into surrender. The Blitz opened a new chapter in the book of WWII. Hitler wanted to reduce London to a pile of ashes and rubble. To accomplish this feat, the Germans introduced an entirely new air-raid strategy. Guided by a new tracking system, that allowed them to locate London even during government imposed blackouts, the Germans dropped a barrage of incendiary bombs over London. These small, tubular objects would lodge themselves in buildings and start small fires throughout the city. While harmless in small numbers, the Germans dropped tens of thousands of these incendiary bombs on London. As fires spread, the German bombers then began to drop massive explosives that leveled buildings throughout the city. On the front lines in the streets of London, fire brigades scrambled to contain the fires. Britain’s Auxiliary Fire Service (AFS) was established in 1937 to assist the regular fire brigades in the event of all-out war. When the Blitz took London by storm in 1940, the Auxiliary Fire Service was called into action. The AFS was made up of over 20,000 part-time and emergency full-time volunteers. Both men and women were played large roles in the AFS. Whether they were pump operators or communication staffers, there was still one glaring trait shared by many of these brave volunteers: they had no experience fighting fires (90% had never fought fires before the Blitz). While many lacked experience, the AFS played a major role in holding off the fires that threatened to reduce Britain to a pile of ashes. Churchill called AFS members “heroes with grimy faces.

Criminal law in the shadows: creating offences in delegated legislation

Substantial numbers of criminal offences are created in the UK in delegated legislation, often carrying heavy maximum penalties. The majority are created in statutory instruments passed under the negative resolution procedure, which offers very limited opportunity for scrutiny and does not involve a parliamentary vote. This phenomenon has slipped under the radar of orthodox criminal law scholarship, where debate has focused primarily on the criteria that should be used to determine the content of the criminal law and on the principles to which such offences should conform, rather than on the process of creating criminal offences. Creating offences in delegated legislation raises questions of democratic legitimacy and has resulted in criminal offences being created which do not conform to basic principles of fair notice and proportionality of penalty. To address this, we propose that parliamentary approval should be required for all serious offences. It would be impractical to do this for all criminal offences, and direct participation in the legislative process via consultation can act as an alternative (or additional) legitimating principle. This does, however, require that the consultation process complies with certain basic minimum requirements, and we explain how these requirements might appropriately be framed

Recommended Practices Guide Securing WLANs using 802.11i

This paper addresses design principles and best practices regarding the implementation and operation of Wireless LAN (WLAN) communication networks based on the 802.11i security standard. First, a general overview of WLAN technology and standards is provided in order to ground the discussion in the evolution of WLAN standards and security approaches. This is followed by a detailed explanation of the 802.11i standard for securing WLAN networks. Principles for designing secure WLAN networks are then presented, followed by a list of specific best practices that can be used as a guideline for organizations considering the deployment of WLAN networks for non-critical control and monitoring applications. Finally, a section on technical issues and considerations for deploying WLAN networks in critical environments is presented

Emissions Trading, Electricity Industry Restructuring and Investment in Pollution Abatement

The NOx State Implementation Plan Call was designed to facilitate cost effective reductions of nitrogen oxides emissions from large stationary sources (primarily electricity generators) through the introduction of an emissions trading program. I investigate the relationship between economic regulation and firms' long-run response to the incentives created by this emissions trading program. I estimate a discrete choice model of the firm's compliance decision, controlling for unit-level variation in compliance costs and using exogenous variation in state-level electricity industry restructuring activity to identify an e¤ect of electricity market regulation on generators' environmental compliance strategy choices. I present evidence that differences in economic regulation across states have resulted in a disproportionate amount of the mandated emissions reductions occurring in more regulated electricity markets. Unfortunately, these are the areas least in need of pollution control.Environmental Economics and Policy,

The Development Of The ARP Colored Vocational High School, ARP, Texas, As A Consolidated School

If one peruses various indexes to studies in the numerous areas of education, he will observe the paucity of investigations dealing with the history and development of institutions whether they be universities, colleges, high schools, or elementary schools. Ever since the educational renaissance which began in the United States during the latter part of the eighteenth century, educational institutions have been constantly aware that the world Is in a state of continual flux and; therefore, to keep pace with the progress of the world, curricula must be constantly revised and improved to meet the students\u27 needs in their respective residential areas. In line with this philosophy, schools have consolidated for the purpose of better serving a larger rural area and community. And because the larger student populations of a consolidated area and community will not all attend college or university, industrial arts and homemaking courses have been included in the curriculum. Thus the school seeks to prepare people for life and to serve the community by increasing the happiness, hopes, and aspirations of the people who reside in it. The growth of colored secondary schools is an interesting field for study. When one considers the fact that the number of schools offering secondary education for colored people has Increased from fewer than 100 to approximately 1,400 within a generation, and the more significant fact that the enrollment of Negro high school pupils has risen from 4,000 to 167,000 during the same period, the need for investigation of the factors involved in this tremendous educational advance and the implications of this movement become immediately apparent. As the high school enrollment increased, the need for industrial high schools correspondingly increased. The provision for industrial education in rural high schools for colored pupils in Texas helped to extend the Tuskegee Institute idea of Booker T. Washington— education of the hands. But Washington\u27s idea, while new to America, was a part of the philosophy of the empirics who contended that knowledge is gained only through observation and practical experience. Thus the idea behind the Arp Colored Industrial High School is that of preparing the pupils to live a better and fuller life in the community. In so doing it is hoped that they will live the more abundant life

A Proposed Adult Education Program For The ARP Colored School Community, ARP, Texas

It has been recognized as a truism that present-day problems resulting from advances due to an ever-increasing technology give rise to a greater need for adult education. This need has not always been accompanied by tangible effort toward complete satisfaction. Nevertheless, leaders in the field of adult education point out quite clearly the necessity for greater emphasis in this regard. For example, Strayer^1 has pointed out the significance of adult education to American culture. He states: As society advances in complexity, the need for adult education increases. The only type of society in which adult education has no place is one that experiences no technological or social changes, one in which there is no opportunity for occupational or professional advancement because everyone lives and works on the same dead level and one in which there is no hope for heightened appreciation or greater comfort. That type of society was left behind by our ancestors when they began their rise from savagery and each year we move farther from it. This explains why the pressure is so insistent to make adult education a constantly more important factor in our daily living. It will readily be conceded that the individual adult under the condition of life presently is in the midst of a large group of new conduct making and conduct-changing forces. Modern inventions have moved the barriers that made for social and individual isolation. Reeves and others describe adults in our present social order as: The adult who participates in some kind of educational activity includes all types of men and women: the type of person who could not or would not go to school in youth and must now attempt to gain the skills he lacks; the youngster who quit school early to go to work only to find later that he needs more study; the middle-age person who now has time to take up those interests which were formerly denied him; the parent who feels that the job of rearing children in a changing world is beyond the range of ordinary instinctive reactions; the foreigner who seeks to learn the strange language and customs of the United States in short, all persons who have a driving desire to keep abreast of complex and changing times. The agencies that contribute directly to educational activities for adults are many and varied; a partial list would include: the public school, agricultural extension services; libraries and museums; college and university extensions; including home studies; federal and emergency agencies; proprietary schools both resident and correspondence; special schools for adults, •religious, welfare, and service agencies; industries and other corporations maintaining personal training programs; and agencies operating in special environments, such as prisons, sanitariums, and settlements. The adult education activities are supported by tax funds, by gifts and endowments, by students for membership fees, or by a combination of these means. Torbert^emphasizes adult education as a public responsibility