Magnon squeezing in an antiferromagnet: reducing the spin noise below the standard quantum limit

At absolute zero temperature, thermal noise vanishes when a physical system is in its ground state, but quantum noise remains as a fundamental limit to the accuracy of experimental measurements. Such a limitation, however, can be mitigated by the formation of squeezed states. Quantum mechanically, a squeezed state is a time-varying superposition of states for which the noise of a particular observable is reduced below that of the ground state at certain times. Quantum squeezing has been achieved for a variety of systems, including the electromagnetic field, atomic vibrations in solids and molecules, and atomic spins, but not so far for magnetic systems. Here we report on an experimental demonstration of spin wave (i.e., magnon) squeezing. Our method uses femtosecond optical pulses to generate correlations involving pairs of magnons in an antiferromagnetic insulator, MnF2. These correlations lead to quantum squeezing in which the fluctuations of the magnetization of a crystallographic unit cell vary periodically in time and are reduced below that of the ground state quantum noise. The mechanism responsible for this squeezing is stimulated second order Raman scattering by magnon pairs. Such squeezed states have important ramifications in the emerging fields of spintronics and quantum computing involving magnetic spin states or the spin-orbit coupling mechanism

A comparative study of enrollment patterns in three east Pottawattamie County school districts

In 1971 a study was conducted for the purpose of assessing the benefits of possible reorganization of the Carson-Macedonia, Oakland and Treynor Community School Districts. In this study the school enrollments were studied for the years 1964-1965 through the 1970-1971 school year and enrollment projections were made through the 1974-1975 school year. The enrollments were projected for each school district and were combined into one larger configuration for its implications for staffing, class offerings, busing, facilities and financial needs

International Aid in Afghanistan: Examining the Effectiveness of Traditional Aid and Development Programs

The US‐led invasion of Afghanistan in 2001 brought to light the comprehensive destruction of the Afghan state. Twenty years of continuous war had ravaged the country, and with the Taliban’s expulsion of western aid agencies, Afghans were further deprived of their basic needs. The international community has rallied around this cause, donating nearly $40 billion in aid since 2001 to help develop Afghanistan. However, this international investment has not yielded optimal results; fundamental mistakes have limited the growth in capacity of the Afghan government and its people. Through analyzing the effectiveness of the major donor programs, a key lesson was learned: the absence of a unified development program has undermined the growth and capacity of the Afghan government. International aid programs in Afghanistan have revealed that providing a service of need trumps increasing the capacity of governance and rule of law. The status quo cannot persist—short‐term humanitarian efforts have been maxed‐out and need to shift to long‐term sustainable projects. To ensure the success of the Afghan state and remove its dependence on international aid, it is imperative to learn from past international aid mistakes and apply the proper changes to Afghanistan

Complexity reduction of astrochemical networks

We present a new computational scheme aimed at reducing the complexity of the chemical networks in astrophysical models, one which is shown to markedly improve their computational efficiency. It contains a flux-reduction scheme that permits to deal with both large and small systems. This procedure is shown to yield a large speed-up of the corresponding numerical codes and provides good accord with the full network results. We analyse and discuss two examples involving chemistry networks of the interstellar medium and show that the results from the present reduction technique reproduce very well the results from fuller calculations.Comment: 9 pages, 7 figures, accepted for publication in Monthly Notices of the Royal Astronomical Society Main Journa

Pembuatan Arsitektur Aplikasi Di Perusahaan Transportasi XYZ Menggunakan Metode Enterprise Architecture Planning (EAP)

Transportation company XYZ is a company engaged in bus-based transport services. Most of the company\u27s business processes are done manually and don\u27t have any integrated information system. The company has a program created by a freelance programm, but the program\u27s features are still incompletes. Thus the analysis and design of enterprise architecture using Enterprise Architecture metod (EAP) are needed for the transportation company XYZ. The first process is analyze the business model and business strategy of the company. After that, identification process to know what information technology that company has, its problems, and company\u27s needs ini the present and in the future. After all information are gathered then design of data architecture, aplication architecture, and technology architecture process were conducted

Evidence of very low metallicity and high ionization state in a strongly lensed, star-forming dwarf galaxy at z=3.417

We investigate the gas-phase metallicity and Lyman Continuum (LyC) escape fraction of a strongly gravitationally lensed, extreme emission-line galaxy at z=3.417, J1000+0221S, recently discovered by the CANDELS team. We derive ionization and metallicity sensitive emission-line ratios from H+K band LBT/LUCI medium resolution spectroscopy. J1000+0221S shows high ionization conditions, as evidenced by its enhanced [OIII]/[OII] and [OIII]/Hbeta ratios. Consistently, strong-line methods based on the available line ratios suggest that J1000+0221S is an extremely metal-poor galaxy, with a metallicity of 12+log(O/H) < 7.44 (< 5% solar), placing it among the most metal-poor star-forming galaxies at z > 3 discovered so far. In combination with its low stellar mass (2x10^8 Msun) and high star formation rate (5 Msun/yr), the metallicity of J1000+0221S is consistent with the extrapolation to low masses of the mass-metallicity relation traced by Lyman-break galaxies at z > 3, but it is 0.55 dex lower than predicted by the fundamental metallicity relation at z < 2.5. These observations suggest the picture of a rapidly growing galaxy, possibly fed by the massive accretion of pristine gas. Additionally, deep LBT/LBC in the UGR bands are used to derive a limit to the LyC escape fraction, thus allowing us to explore for the first time the regime of sub-L* galaxies at z > 3. We find a 1sigma upper limit to the escape fraction of 23%, which adds a new observational constraint to recent theoretical models predicting that sub-L* galaxies at high-z have high escape fractions and thus are the responsible for the reioization of the Universe.Comment: 5 pages, 3 figures and 1 table. Accepted for publication in ApJ Letter

The counselor educator social justice attitudes instrument: An exploratory process assessing dimensionality

Despite multiple calls for social justice in counselor education in the past four decades, the frequency of social justice practices in counselor education remains unclear. In order to better understand social justice practices among counselor educators, it is useful to first understand counselor educator attitudes towards social justice. This manuscript presents the construction of the Counselor Educator Social Justice Attitudes Instrument, an instrument measuring counselor educator attitudes towards social justice. In this manuscript, we outline the rationale for the instrument, the development of the instrument, and a critical assessment of the instrument. The final 24-item instrument measuring counselor educator attitudes towards social justice is included. The final instrument is based on three factors accounting for 68.29% variance

Life Support System Considerations for Space Station

With the growing desire to initiate a Space Station program, the interest in advanced, regenerative life support systems is also increasing. This paper briefly reviews this future spacecraft and concentrates on the advanced technology in some of the key functions of life support for this application. This paper reviews the basics of life support and its importance within a space station program. It concentrates«on the impact of major requirements and discusses some of the key influences that impact the design of the system. It also projects some of the key functional areas of the life support system which are most likely to be implemented from today\u27s current technology. The imminent availability of the Space Shuttle has rekindled interest in the longer duration space missions and permanent orbiting space platforms. Studies are underway to define missions and concept the orbiting facilities based on the capabilities available with and limitations imposed by the Space Transportation System. A work base in space is required to economically perform the long duration, complex missions of the future and to utilize the Space Shuttle in its intended role as a space truck. The term Space Station is again coming into vogue, although other titles for this program are currently in use

Observation of Surface-Avoiding Waves: A New Class of Extended States in Periodic Media

Coherent time-domain optical experiments on GaAs-AlAs superlattices reveal the exis-tence of an unusually long-lived acoustic mode at ~ 0.6 THz, which couples weakly to the environment by evading the sample boundaries. Classical as well as quantum states that steer clear of surfaces are generally shown to occur in the spectrum of periodic struc-tures, for most boundary conditions. These surface-avoiding waves are associated with frequencies outside forbidden gaps and wavevectors in the vicinity of the center and edge of the Brillouin zone. Possible consequences for surface science and resonant cavity ap-plications are discussed.Comment: 16 pages, 3 figure