Quantum feedback and adaptive measurements

Summary form only given. Although real-time feedback of measured signals is an essential component of sensing and control in classical settings, models for quantum feedback that are rigorous yet useful have only become possible since the advent of measurement-based quantum trajectory theory. The quantum feedback scenario introduces new concerns of coherence and measurement backaction, but recent work has shown that these can be treated properly in a formal integration of quantum trajectory theory with standard state-space formulations of filtering and control theory. Pioneering studies by H. M. Wiseman have shown that such models can be used to design and to analyze realistic schemes for adaptive homodyne measurement and for feedback control of atomic motion. Much of the ongoing research in our group focuses on the experimental implementation of such schemes. For a broad range of quantum feedback scenarios, certain recurring technical issues arise out of the need to perform complex, high-bandwidth processing of measured signals. We are developing a "rapid-prototyping" approach to refining signal processing and feedback algorithms via quantum trajectory simulation on a PC, followed by translation of the algorithms into hardware Description language (HDL)

A NeISS collaboration to develop and use e-infrastructure for large-scale social simulation

The National e-Infrastructure for Social Simulation (NeISS) project is focused on developing e-Infrastructure to support social simulation research. Part of NeISS aims to provide an interface for running contemporary dynamic demographic social simulation models as developed in the GENESIS project. These GENESIS models operate at the individual person level and are stochastic. This paper focuses on support for a simplistic demographic change model that has a daily time steps, and is typically run for a number of years. A portal based Graphical User Interface (GUI) has been developed as a set of standard portlets. One portlet is for specifying model parameters and setting a simulation running. Another is for comparing the results of different simulation runs. Other portlets are for monitoring submitted jobs and for interfacing with an archive of results. A layer of programs enacted by the portlets stage data in and submit jobs to a Grid computer which then runs a specific GENESIS model program executable. Once a job is submitted, some details are communicated back to a job monitoring portlet. Once the job is completed, results are stored and made available for download and further processing. Collectively we call the system the Genesis Simulator. Progress in the development of the Genesis Simulator was presented at the UK e- Science All Hands Meeting in September 2011 by way of a video based demonstration of the GUI, and an oral presentation of a working paper. Since then, an automated framework has been developed to run simulations for a number of years in yearly time steps. The demographic models have also been improved in a number of ways. This paper summarises the work to date, presents some of the latest results and considers the next steps we are planning in this work

Programmable Logic Devices in Experimental Quantum Optics

We discuss the unique capabilities of programmable logic devices (PLD's) for experimental quantum optics and describe basic procedures of design and implementation. Examples of advanced applications include optical metrology and feedback control of quantum dynamical systems. As a tutorial illustration of the PLD implementation process, a field programmable gate array (FPGA) controller is used to stabilize the output of a Fabry-Perot cavity

The diverse world of social enterprise: a collection of social enterprise stories

Purpose – The purpose of this paper is to highlight the diverse world of social enterprise. Design/methodology/approach – This paper profiles 11 different social enterprises from around the world. These range from a profit-achieving business in a very competitive industry, but one with strong social principles, through a profitable workers' co-operative to ones needing to find financial sustainability if they are to continue their social aspirations. The paper discusses a number of key issues in defining an organisation as a social enterprise and highlights the central issue of measuring success and impact. Findings – In some of the enterprises the important contribution of a pivotal social entrepreneur is apparent. The need to create and add value for customers and clients is always apparent, as is the need to find effective routes to market. It can be concluded that whilst certain beliefs and principles are routinely evident, social enterprises most certainly cannot be described as “one-size-fits-all”. Originality/value – The paper presents a collection of social enterprise stories

The Incompatibility of Certain Alcohol and Soap Frothers

The purpose of this thesis is to elucidate this phenomena of frother incompatibility, and to offer an explanation based upon several divergent lines of investigation. The research was limited to four common frothing agents, namely, pine oil, n-amyl alcohol, sodium oleate, and sodium lauryl sulphate (Dreft)

Robust quantum parameter estimation: coherent magnetometry with feedback

We describe the formalism for optimally estimating and controlling both the state of a spin ensemble and a scalar magnetic field with information obtained from a continuous quantum limited measurement of the spin precession due to the field. The full quantum parameter estimation model is reduced to a simplified equivalent representation to which classical estimation and control theory is applied. We consider both the tracking of static and fluctuating fields in the transient and steady state regimes. By using feedback control, the field estimation can be made robust to uncertainty about the total spin number