74 research outputs found
Reading of the Ricardian Prologue of John Gower\u27s Confessio Amantis
No full textThe entire reading is approximately 54 minutes in length.
Readers for the text (in order) are Daniel Berger, Madison Bradley, Shannon Byrne, Brandon Carey, Faith Carson, Fiona Copeland, Lauren Graham, Rae Hodenfield, Sarah Hojsak, Giselle Horrell, Sarah Howell, Joy Jones, Morgan Kentsbeer, Laura Maurer, Kevin Medina, Nic Shandera, Matthew Sherman, Emily Shue, Catherine Urbanski, and Dr. Kara McShane.
The text is available online through the University of Rochester Middle English Texts Series at http://d.lib.rochester.edu/teams/text/peck-gower-confessio-amantis-volume-1-prologue
Response to `Local and global definitions of time: Cosmology and quantum theory'
No full textI will discuss the notion of time and spatial finiteness from the perspective of observational cosmology. Our observed universe is well described at early times by small fluctuations in the spatial gravitational field, distributed homogeneously and isotropically on an otherwise smooth background spacetime. The dominant paradigm for an even earlier phase of the evolution of our universe typically generates a space similar to what we observe but with vastly larger spatial extent. Even in a classical theory, the fact that we observe only a finite volume of space and time means that there are statistical uncertainties in testing and constraining the theory. In the absence of evidence that our observable universe is all there is, the cosmological principle suggests that we should consider ourselves to be a typical region of a vastly larger space. I will consider the problems of time and largest spatial scale of the universe from the perspective of accepting an imperfect and incomplete theory on scales currently out of reach of our necessarily imperfect and incomplete observations. The question then is how to work in incremental steps to push for a broader range of understanding
Natural disorder distributions from measurement
No full textWe consider scenarios where the dynamics of a quantum system are partially
determined by prior local measurements of some interacting environmental
degrees of freedom. The resulting effective system dynamics are described by a
disordered Hamiltonian, with spacetime-varying parameter values drawn from
distributions that are generically neither flat nor Gaussian. This class of
scenarios is a natural extension of those where a fully non-dynamical
environmental degree of freedom determines a universal coupling constant for
the system. Using a family of quasi-exactly solvable anharmonic oscillators, we
consider environmental ground states of nonlinearly coupled degrees of freedom,
unrestricted by a weak coupling expansion, which include strongly quantum
non-Gaussian states. We derive the properties of distributions for both
quadrature and photon number measurements. Measurement-induced disorder of this
kind is likely realizable in laboratory quantum systems and, given a notion of
naturally occurring measurement, suggests a new class of scenarios for the
dynamics of quantum systems in particle physics and cosmology.Comment: 27 pages, 11 figure
Classifying the non-time-local and entangling dynamics of an open qubit system
No full textAbstract We study families of dynamical maps generated from interactions with varying degrees of symmetry. For a family of time-independent Hamiltonians, we demonstrate the relationship between symmetry, strong-coupling, perfect entanglers, non-Markovian features, and non-time-locality. We show that by perturbing the initial environment state, effective time-local descriptions can be obtained that are non-singular yet capture essential non-unitary features of the reduced dynamics. We then consider a time-dependent Hamiltonian that changes the degree of symmetry by activating a dormant degree of freedom. In this example we find that the one-qubit reduced dynamics changes dramatically. These results can inform the construction of effective theories of open systems when the larger system dynamics is unknown
Classifying the non-time-local and entangling dynamics of an open qubit system
No full textWe study families of dynamical maps generated from interactions with varying
degrees of symmetry. For a family of time-independent Hamiltonians, we
demonstrate the relationship between symmetry, strong-coupling, perfect
entanglers, non-Markovian features, and non-time-locality. We show that by
perturbing the initial environment state, effective time-local descriptions can
be obtained that are non-singular yet capture essential non-unitary features of
the reduced dynamics. We then consider a time-dependent Hamiltonian that
changes the degree of symmetry by activating a dormant degree of freedom. In
this example we find that the one-qubit reduced dynamics changes dramatically.
These results can inform the construction of effective theories of open systems
when the larger system dynamics is unknown.Comment: 29 pages, 5 figur
Large non-Gaussian halo bias from single field inflation
No full textWe calculate Large Scale Structure observables for non-Gaussianity arising from non-Bunch-Davies initial states in single field inflation. These scenarios can have substantial primordial non-Gaussianity from squeezed (but observable) momentum configurations. They generate a term in the halo bias that may be more strongly scale-dependent than the contribution from the local ansatz. We also discuss theoretical considerations required to generate an observable signature. © 2012 IOP Publishing Ltd and Sissa Medialab srl
Large-scale anomalies in the cosmic microwave background as signatures of non-Gaussianity
No full textWe derive a general expression for the probability of observing deviations from statistical isotropy in the cosmic microwave background (CMB) if the primordial fluctuations are non-Gaussian and extend to superhorizon scales. The primary motivation is to properly characterize the monopole and dipole modulations of the primordial power spectrum that are generated by the coupling between superhorizon and subhorizon perturbations. Unlike previous proposals for generating the hemispherical power asymmetry, we do not assume that the power asymmetry results from a single large superhorizon mode. Instead, we extrapolate the observed power spectrum to superhorizon scales and compute the power asymmetry that would result from a specific realization of non-Gaussian perturbations on scales larger than the observable universe. Our study encompasses many of the scenarios that have been put forward as possible explanations for the CMB hemispherical power asymmetry. We confirm our analytic predictions for the probability of a given power asymmetry by comparing them to numerical realizations of CMB maps. We find that non-local models of non-Gaussianity and scale-dependent local non-Gaussianity produce scale-dependent modulations of the power spectrum, thereby potentially producing both a monopolar and a dipolar power modulation on large scales. We then provide simple examples of finding the posterior distributions for the parameters of the bispectrum from the observed monopole and dipole modulations
Increasing extractable work in small qubit landscapes
No full textAn interesting class of physical systems, including those associated with
life, demonstrates the ability to hold thermalization at bay and perpetuate
states of high free-energy compared to a local environment. In this work, we
study quantum systems with no external sources or sinks for energy, heat, work,
or entropy, that allow for high free-energy subsystems to form and persist. We
initialize systems of qubits in mixed, uncorrelated states and evolve them
subject to a conservation law. We find that four qubits make up the minimal
system for which these restricted dynamics and initial conditions allow an
increase in extractable work for a subsystem. On landscapes of eight
co-evolving qubits, interacting in randomly selected subsystems at each step,
we demonstrate that restricted connectivity and an inhomogeneous distribution
of initial temperatures both lead to landscapes with longer intervals of
increasing extractable work for individual qubits. We demonstrate the role of
correlations that develop on the landscape in enabling a positive change in
extractable work.Comment: 34 pages and 19 figure
Spontaneously interacting qubits from Gauss-Bonnet
No full textBuilding on previous constructions examining how a collection of small,
locally interacting quantum systems might emerge via spontaneous symmetry
breaking from a single-particle system of high dimension, we consider a larger
family of geometric loss functionals and explicitly construct several classes
of critical metrics which "know about qubits" (KAQ). The loss functional
consists of the Ricci scalar with the addition of the Gauss-Bonnet term, which
introduces an order parameter that allows for spontaneous symmetry breaking.
The appeal of this method is two-fold: (i) the Ricci scalar has already been
shown to have KAQ critical metrics and (ii) exact equations of motions are
known for loss functionals with generic curvature terms up to two derivatives.
We show that KAQ critical metrics, which are solutions to the equations of
motion in the space of left-invariant metrics with fixed determinant, exist for
loss functionals that include the Gauss-Bonnet term. We find that exploiting
the subalgebra structure leads us to natural classes of KAQ metrics which
contain the familiar distributions (GUE, GOE, GSE) for random Hamiltonians. We
introduce tools for this analysis that will allow for straightfoward, although
numerically intensive, extension to other loss functionals and higher-dimension
systems.Comment: 29 pages, 7 figure
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