Nonlinear optics with less than one photon

We demonstrate suppression and enhancement of spontaneous parametric down- conversion via quantum interference with two weak fields from a local oscillator (LO). Pairs of LO photons are observed to upconvert with high efficiency for appropriate phase settings, exhibiting an effective nonlinearity enhanced by at least 10 orders of magnitude. This constitutes a two-photon switch, and promises to be useful for a variety of nonlinear optical effects at the quantum level.Comment: 8 pages, 5 figure

Nonlinearity in Single Photon Detection: Modeling and Quantum Tomography

Single Photon Detectors are integral to quantum optics and quantum information. Superconducting Nanowire based detectors exhibit new levels of performance, but have no accepted quantum optical model that is valid for multiple input photons. By performing Detector Tomography, we improve the recently proposed model [M.K. Akhlaghi and A.H. Majedi, IEEE Trans. Appl. Supercond. 19, 361 (2009)] and also investigate the manner in which these detectors respond nonlinearly to light, a valuable feature for some applications. We develop a device independent model for Single Photon Detectors that incorporates this nonlinearity

Comment on "A linear optics implementation of weak values in Hardy's paradox"

A recent experimental proposal by Ahnert and Payne [S.E. Ahnert and M.C. Payne, Phys. Rev. A 70, 042102 (2004)] outlines a method to measure the weak value predictions of Aharonov in Hardy's paradox. This proposal contains flaws such as the state preparation method and the procedure for carrying out the requisite weak measurements. We identify previously published solutions to some of the flaws.Comment: To be published in Physical Review

The Impacts of Alternative Electric Rate Structures for Irrigation: Clay-Union and Union RECs

In this research report, the impacts of alternative electric rates and rate structures for irrigation for the Clay-Union rural electric cooperatives (RECs) are evaluated. Consideration is given to both different levels and different forms of electric rate changes

Households and Rural Water Systems

This bulletin reports household impacts of rural water system development based on a case study of the Brookings-Deuel Rural Water System. This study was conducted as part of Project B-056-S.Dak. funded by the United States Department of the Interior, Office of Water Research and Technology. This bulletin is written audiences. One audience is made of rural water system planners, public officials, and policy-makers who have worked with rural water systems. These readers will understand the results and findings, although the description of specific statistical procedures may not be exactly clear to them. The other audience consists of community rural development specialists and other researchers doing work in rural water systems

Public Impacts of Rural Water Systems: A Case Study

A case study of the Brookings-Deuel Rural Water System was undertaken to estimate the effects of the system on the revenues and expenditures of the local governments which serve its members

Optimal experiment design revisited: fair, precise and minimal tomography

Given an experimental set-up and a fixed number of measurements, how should one take data in order to optimally reconstruct the state of a quantum system? The problem of optimal experiment design (OED) for quantum state tomography was first broached by Kosut et al. [arXiv:quant-ph/0411093v1]. Here we provide efficient numerical algorithms for finding the optimal design, and analytic results for the case of 'minimal tomography'. We also introduce the average OED, which is independent of the state to be reconstructed, and the optimal design for tomography (ODT), which minimizes tomographic bias. We find that these two designs are generally similar. Monte-Carlo simulations confirm the utility of our results for qubits. Finally, we adapt our approach to deal with constrained techniques such as maximum likelihood estimation. We find that these are less amenable to optimization than cruder reconstruction methods, such as linear inversion.Comment: 16 pages, 7 figure

Mixed Integer Linear programming Model Electric Rate Structure-Irrigation Study: Clay-Union, Union, Cherry-Todd, and Cam-Wal RECs

This is the second in a series of five Economics Department reports on a research project. The Economic Impact of Alternative Electric Rate Structures on Energy and Water Use . sponsored by the South Dakota Agricultural Experiment Station. Supplemental funding for the research was provided by the Western Area Power Administration (WAPA). Golden. Colorado. The purpose of this report is to acquaint the reader with the overall model used in the study and the specific way that the electric rate structures were modeled. This model builds on. b~t goes beyond. the one developed and used by Robert A. Young and. associates in their study of electric rate structures for irrigation in Colorado. The primary way in which this model extends beyond Young\u27s model is that it permits simultaneous (rather than one-at-a-time) attention to all three basic features of electric rate structures for irrigation, namely. annual minimum charges. monthly demand charges. and block rate energy charges. The primary intended audiences for the report are graduate students and research-peers with an interest in analyzing electric rate structures for irrigation

Fall Lambing Performance of Purebred Columbia and Hampshire Ewes

This study was initiated to evaluate the performance of purebred Columbia and Hampshire ewes selected for a September-October once a year lambing system in a effort to provide a more continuous supply of lambs to the market