1,371 research outputs found
Complexity of Model Testing for Dynamical Systems with Toric Steady States
In this paper we investigate the complexity of model selection and model
testing for dynamical systems with toric steady states. Such systems frequently
arise in the study of chemical reaction networks. We do this by formulating
these tasks as a constrained optimization problem in Euclidean space. This
optimization problem is known as a Euclidean distance problem; the complexity
of solving this problem is measured by an invariant called the Euclidean
distance (ED) degree. We determine closed-form expressions for the ED degree of
the steady states of several families of chemical reaction networks with toric
steady states and arbitrarily many reactions. To illustrate the utility of this
work we show how the ED degree can be used as a tool for estimating the
computational cost of solving the model testing and model selection problems
Measurement-based synthesis of multiqubit entangled states in superconducting cavity QED
Entangled multiqubit states may be generated through a dispersive collective quantum nondemolition measurement of superconducting qubits coupled to a microwave transmission line resonator. Using the quantum trajectory approach, we analyze the stochastic measurement traces that would be observed in experiments. We illustrate the synthesis of three-qubit W and Greenberger-Horne-Zeilinger states, and we analyze how the fidelity and the entanglement evolve in time during the measurement. We discuss the influence of decoherence and relaxation, as well as of imperfect control over experimental parameters. We show that the desired states can be generated on time scales much faster than the qubit decoherence rates
Consequences of wall stiffness for a beta-soft potential
Modifications of the infinite square well E(5) and X(5) descriptions of
transitional nuclear structure are considered. The eigenproblem for a potential
with linear sloped walls is solved. The consequences of the introduction of
sloped walls and of a quadratic transition operator are investigated.Comment: RevTeX 4, 8 pages, as published in Phys. Rev.
Finding Joy in Our Profession: John F. Helmer on Library Consortia
John F. Helmer, executive director of the Orbis Cascade Alliance, has had an amazing career. In this interview with Valerie Horton, Helmer shares his insights, humor, and deep understanding of our profession. John sees the best of library collaborations as “entrepreneurial, spirited, ambitious,” and leading to the development of critically important working relationships. John offers many nuggets of wisdom for collaborative leaders in this interview. His insights into failure should be required reading in our profession. He argues that if you aren’t failing, you aren’t trying hard enough
Optimal control of circuit quantum electrodynamics in one and two dimensions
Optimal control can be used to significantly improve multi-qubit gates in
quantum information processing hardware architectures based on superconducting
circuit quantum electrodynamics. We apply this approach not only to dispersive
gates of two qubits inside a cavity, but, more generally, to architectures
based on two-dimensional arrays of cavities and qubits. For high-fidelity gate
operations, simultaneous evolutions of controls and couplings in the two
coupling dimensions of cavity grids are shown to be significantly faster than
conventional sequential implementations. Even under experimentally realistic
conditions speedups by a factor of three can be gained. The methods immediately
scale to large grids and indirect gates between arbitrary pairs of qubits on
the grid. They are anticipated to be paradigmatic for 2D arrays and lattices of
controllable qubits.Comment: Published version
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