Towards a Coulomb gas of instantons in the SO(4)xU(1) Higgs model on R_4

The $SO(4)\times U(1)$ Higgs model on $\R_4$ is extended by a $F^3$ term so that the action receives a nonvanishing contribution from the interactions of 2-instantons and 3-instantons, and can be expressed as the inverse of the Laplacian on $\R_4$ in terms of the mutual distances of the instantons. The one-instanton solutions of both the basic and the extended models have been studied in detail numerically.Comment: 29 pages LaTeX, 4 Figures available from authors on reques

“Gilded Misery”: The Robie Women in Loyalist Exile and Repatriation, 1775–1790

Forced to flee Marblehead, Massachusetts, in late April 1775, Thomas Robie, his wife Mary Bradstreet Robie, and their four children were among the earliest Loyalist refugees to land in Nova Scotia. The arrival of thousands more Loyalists in 1783 brought widespread hardship to the region, but the collective suffering also provided Mary Bradstreet Robie and her two daughters the opportunity to contribute to the Loyalist community and assert their will within the family. This study of the Robie family demonstrates that Loyalist women were not simply domestic figures of support nor were they resigned to exile as passive followers of husbands and fathers.Forcés de fuir Marblehead, au Massachusetts, à la fin d’avril 1775, Thomas Robie, sa femme, Mary Bradstreet Robie, et leurs quatre enfants furent parmi les premiers Loyalistes à débarquer en Nouvelle-Écosse. L’arrivée de milliers d’autres Loyalistes en 1783 entraîna des difficultés généralisées dans la région, mais la souffrance collective fournit également à Mary Bradstreet Robie et à ses deux filles l’occasion d’apporter une contribution à la communauté loyaliste et d’affirmer leur volonté au sein de la famille. La présente étude de la famille Robie démontre que les femmes loyalistes n’étaient pas simplement une source de soutien au foyer, pas plus qu’elles n’étaient résignées à s’exiler en suivant passivement les maris et les pères de famille

“Unknown and Unlamented”: Loyalist Women in Nova Scotia from Exile to Repatriation, 1775-1800

Between 1775 and 1784, more than 60,000 people fled the American states in order to escape the divisive civil war that tore apart communities and individual families. More than half of these people moved north to the maritime colonies of British Canada. While some of these “loyalists” were ardent supporters of the British Empire, many more found their allegiances thrust upon them due to their status as dependents. This study examines the experience of refugee women in Nova Scotia in order to better understand not only Revolutionary-era allegiance, but also women’s important public and private roles in exile and repatriation. Although historians have portrayed loyalist women as consoling wives and daughters who dutifully submitted to men’s will, refugee women were not merely passive acceptors of their fate, nor resigned to domestic roles of support. Paying particular attention to both women’s expressions of emotion and the societal norms that governed late eighteenth-century society, this dissertation examines how loyalist women’s empathetic actions carried tremendous power in communities where loss and hardship were endemic. The widespread suffering of exile provided women the opportunity to take on important communal roles where they could both demonstrate their own fellow feeling and build the intangible networks that created new communities. Women also wielded their emotions in the home. Unhappy wives and daughters forced reluctant husbands and fathers to reconsider their families’ future as exiles, and brought many back to the United States after the war

Evidence for nonlinear diffusive shock acceleration of cosmic-rays in the 2006 outburst of the recurrent nova RS Ophiuchi

Spectroscopic observations of the 2006 outburst of the recurrent nova RS Ophiuchi at both infrared (IR) and X-ray wavelengths have shown that the blast wave has decelerated at a higher rate than predicted by the standard test-particle adiabatic shock-wave model. Here we show that the observed evolution of the nova remnant can be explained by the diffusive shock acceleration of particles at the blast wave and the subsequent escape of the highest energy ions from the shock region. Nonlinear particle acceleration can also account for the difference of shock velocities deduced from the IR and X-ray data. The maximum energy that accelerated electrons and protons can have achieved in few days after outburst is found to be as high as a few TeV. Using the semi-analytic model of nonlinear diffusive shock acceleration developed by Berezhko & Ellison, we show that the postshock temperature of the shocked gas measured with RXTE/PCA and Swift/XRT imply a relatively moderate acceleration efficiency.Comment: Accepted for publication in ApJ

Changing social contracts in climate-change adaptation

Risks from extreme weather events are mediated through state, civil society and individual action 1 , 2 . We propose evolving social contracts as a primary mechanism by which adaptation to climate change proceeds. We use a natural experiment of policy and social contexts of the UK and Ireland affected by the same meteorological event and resultant flooding in November 2009. We analyse data from policy documents and from household surveys of 356 residents in western Ireland and northwest England. We find significant differences between perceptions of individual responsibility for protection across the jurisdictions and between perceptions of future risk from populations directly affected by flooding events. These explain differences in stated willingness to take individual adaptive actions when state support retrenches. We therefore show that expectations for state protection are critical in mediating impacts and promoting longer-term adaptation. We argue that making social contracts explicit may smooth pathways to effective and legitimate adaptation

High-Fidelity Z-Measurement Error Correction of Optical Qubits

We demonstrate a quantum error correction scheme that protects against accidental measurement, using an encoding where the logical state of a single qubit is encoded into two physical qubits using a non-deterministic photonic CNOT gate. For the single qubit input states |0>, |1>, |0>+|1>, |0>-|1>, |0>+i|1>, and |0>-i|1> our encoder produces the appropriate 2-qubit encoded state with an average fidelity of 0.88(3) and the single qubit decoded states have an average fidelity of 0.93(5) with the original state. We are able to decode the 2-qubit state (up to a bit flip) by performing a measurement on one of the qubits in the logical basis; we find that the 64 1-qubit decoded states arising from 16 real and imaginary single qubit superposition inputs have an average fidelity of 0.96(3).Comment: 4 pages, 4 figures, comments welcom

Antiphase dynamics in a multimode semiconductor laser with optical injection

A detailed experimental study of antiphase dynamics in a two-mode semiconductor laser with optical injection is presented. The device is a specially designed Fabry-Perot laser that supports two primary modes with a THz frequency spacing. Injection in one of the primary modes of the device leads to a rich variety of single and two-mode dynamical scenarios, which are reproduced with remarkable accuracy by a four dimensional rate equation model. Numerical bifurcation analysis reveals the importance of torus bifurcations in mediating transitions to antiphase dynamics and of saddle-node of limit cycle bifurcations in switching of the dynamics between single and two-mode regimes.Comment: 7 pages, 9 figure

Giant optical Faraday rotation induced by a single electron spin in a quantum dot: Applications to entangling remote spins via a single photon

We propose a quantum non-demolition method - giant Faraday rotation - to detect a single electron spin in a quantum dot inside a microcavity where negatively-charged exciton strongly couples to the cavity mode. Left- and right-circularly polarized light reflected from the cavity feels different phase shifts due to cavity quantum electrodynamics and the optical spin selection rule. This yields giant and tunable Faraday rotation which can be easily detected experimentally. Based on this spin-detection technique, a scalable scheme to create an arbitrary amount of entanglement between two or more remote spins via a single photon is proposed.Comment: 5 pages, 3 figure

An All Optical Fibre Quantum Controlled-NOT Gate

We report the first experimental demonstration of an optical controlled-NOT gate constructed entirely in fibre. We operate the gate using two heralded optical fibre single photon sources and find an average logical fidelity of 90% and an average process fidelity of 0.83<F<0.91. On the basis of a simple model we are able to conclude that imperfections are primarily due to the photon sources, meaning that the gate itself works with very high fidelity.Comment: 4 pages, 4 figures, comments welcom