Spin squeezing of atomic ensembles by multi-colour quantum non-demolition measurements

We analyze the creation of spin squeezed atomic ensembles by simultaneous dispersive interactions with several optical frequencies. A judicious choice of optical parameters enables optimization of an interferometric detection scheme that suppresses inhomogeneous light shifts and keeps the interferometer operating in a balanced mode that minimizes technical noise. We show that when the atoms interact with two-frequency light tuned to cycling transitions the degree of spin squeezing $\xi^2$ scales as $\xi^2\sim 1/d$ where $d$ is the resonant optical depth of the ensemble. In real alkali atoms there are loss channels and the scaling may be closer to $\xi^2\sim 1/\sqrt d.$ Nevertheless the use of two-frequencies provides a significant improvement in the degree of squeezing attainable as we show by quantitative analysis of non-resonant probing on the Cs D1 line. Two alternative configurations are analyzed: a Mach-Zehnder interferometer that uses spatial interference, and an interaction with multi-frequency amplitude modulated light that does not require a spatial interferometer.Comment: 7 figure

Observation of quantum spin noise in a 1D light-atoms quantum interface

We observe collective quantum spin states of an ensemble of atoms in a one-dimensional light-atom interface. Strings of hundreds of cesium atoms trapped in the evanescent fiel of a tapered nanofiber are prepared in a coherent spin state, a superposition of the two clock states. A weak quantum nondemolition measurement of one projection of the collective spin is performed using a detuned probe dispersively coupled to the collective atomic observable, followed by a strong destructive measurement of the same spin projection. For the coherent spin state we achieve the value of the quantum projection noise 40 dB above the detection noise, well above the 3 dB required for reconstruction of the negative Wigner function of nonclassical states. We analyze the effects of strong spatial inhomogeneity inherent to atoms trapped and probed by the evanescent waves. We furthermore study temporal dynamics of quantum fluctuations relevant for measurement-induced spin squeezing and assess the impact of thermal atomic motion. This work paves the road towards observation of spin squeezed and entangled states and many-body interactions in 1D spin ensembles

Assessing the impact of the DIGS curriculum on agricultural literacy in youth

2022 Summer.Includes bibliographical references.This research examines the impact of the DIGS curriculum on agricultural literacy, the breadth of agricultural understanding, and affinity for agriculture. The DIGS curriculum is a third thru fifth-grade curriculum emphasizing hands-on, interactive lessons in eight agricultural pathways. Students participated in each lesson and completed a supplemental activity in the DIGS booklet. This curriculum was implemented over a school year with one monthly lesson and activity. Chapter one assesses the impact of DIGS on agricultural literacy. Researchers define agricultural literacy as understanding agriculture as an integrative system built on experiences, relationships, and inspiring investment in the future of agriculture. The Longhurst Murray Agricultural Literacy Instrument (LMALI) is used to collect pre- and post-scores to evaluate the agricultural knowledge of participants. Researchers then assessed the breadth of agricultural understanding by completing a content analysis on the booklets. The breadth of understanding is broken into three themes based on the definition of agricultural literacy: (1) agriculture as a system, (2) agriculture and relationships, and (3) the future of agriculture. Researchers found that DIGS participants had increased LMALI scores after completing the curriculum, and many had evidence of a breadth of agricultural understanding. Chapter two assesses the impact of the DIGS curriculum on students' affinity for agriculture. Students responded to an affinity survey at the end of the curriculum and completed monthly activities in their DIGS booklets. Researchers performed a content analysis on the booklets and post-curriculum posters to evaluate how students felt about the curriculum and agriculture throughout the process. Researchers found that many students had or developed an affinity for agriculture during the curriculum. Many shared thoughts of wanting to participate in agricultural activities and reported that the curriculum was "fun" and that agriculture was "important." This project demonstrates the impact of the DIGS curriculum on agricultural literacy, a breadth of agricultural understanding, and affinity for agriculture. Overall, the findings show that DIGS impacted all three of these areas; increasing agricultural literacy based on knowledge, demonstrating a breadth of understanding in agriculture, and developing an affinity for agriculture throughout the curriculum

U.S. Foreign Policy in Pakistan: Bringing Pakistan Into Line with American Counterterrorism Interests

This thesis is a review of U.S. foreign policy in Pakistan through a realist lens. It critiques the current state of U.S. policy and recommends that the United States prioritize national security interests, particularly with regards to counterterrorism, over building Pakistani democracy and running civilian aid programs. It then further recommends ways for the United States government to account for ground level dynamics in Pakistani politics in crafting foreign policy aimed at bringing Pakistan into line with U.S. counterterrorism priorities

Redefining Stewardship over Body Parts

This paper proposes one possible avenue for defining a framework to address body parts. I begin with the presumption that given the increasing use of body parts outside of our bodies, either after death or during life, society requires a framework with institutions and rules to govern our body parts. Yet there is no settled framework. Much of the controversy over differing approaches stems from whether people should be able to sell body parts. Thus, each potential framework implicitly addresses the question of monetary value. While multiple possibilities exist, the predominant models are (1) property, most often meaning ownership that permits monetary compensation; (2) stewardship, implying altruism and no monetary compensation to the donor; and (3) a compromise solution involving regulatory bodies, which could assign monetary value under certain circumstances

Rebutting the Fraud on the Market Presumption in Securities Fraud Class Actions: \u3cem\u3eHalliburton II\u3c/em\u3e Opens the Door

In Halliburton Co. v. Erica P. John Fund, Inc. (Halliburton II), the United States Supreme Court reaffirmed the validity of the “fraud on the market” presumption underlying securities fraud class action litigation. This presumption is vital to bringing suits as class actions because it excuses plaintiffs from proving individual reliance on an alleged corporate misstatement on the theory that any public statements made by the company are incorporated into its stock price and consequently relied upon by all investors. Thus, the Court’s decision to uphold the validity of the presumption has been hailed as a significant victory for those who bring securities fraud class actions. Overlooked by many commentators is the fact that in addition to upholding the fraud on the market presumption, the Court established a new avenue for defendants to rebut the presumption at the class certification stage of a case. Defendants can now rebut the presumption before a class is certified by presenting evidence that an alleged corporate misstatement had no impact on the price of the stock. This ruling is significant because securities fraud class actions, as a practical matter, often settle after a class has been certified. This article examines what that ruling could mean for modern securities fraud class action litigation