Fay Dowker

Publications (3)7.37 Total impact

• Article: Quantum Information Processing and Relativistic Quantum Fields

  Dionigi M. T. Benincasa, Leron Borsten, Michel Buck, Fay Dowker
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  ABSTRACT: It is shown that an ideal measurement of a one-particle wave packet state of a relativistic quantum field in Minkowski spacetime enables superluminal signalling. The result holds for a measurement that takes place over an intervention region in spacetime whose extent in time in some frame is longer than the light crossing time of the packet in that frame.
  06/2012;
• Source

  Available from: ArXiv

  Article: The Random Discrete Action for 2-Dimensional Spacetime

  Dionigi M. T. Benincasa, Fay Dowker, Bernhard Schmitzer
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  ABSTRACT: A one-parameter family of random variables, called the Discrete Action, is defined for a 2-dimensional Lorentzian spacetime of finite volume. The single parameter is a discreteness scale. The expectation value of this Discrete Action is calculated for various regions of 2D Minkowski spacetime. When a causally convex region of 2D Minkowski spacetime is divided into subregions using null lines the mean of the Discrete Action is equal to the alternating sum of the numbers of vertices, edges and faces of the null tiling, up to corrections that tend to zero as the discreteness scale is taken to zero. This result is used to predict that the mean of the Discrete Action of the flat Lorentzian cylinder is zero up to corrections, which is verified. The ``topological'' character of the Discrete Action breaks down for causally convex regions of the flat trousers spacetime that contain the singularity and for non-causally convex rectangles.
  11/2010;
• Source

  Available from: ArXiv

  Article: Scalar curvature of a causal set.

  Dionigi M T Benincasa, Fay Dowker
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  ABSTRACT: A one parameter family of retarded linear operators on scalar fields on causal sets is introduced. When the causal set is well approximated by 4 dimensional Minkowski spacetime, the operators are Lorentz invariant but nonlocal, are parametrized by the scale of the nonlocality, and approximate the continuum scalar D'Alembertian square when acting on fields that vary slowly on the nonlocality scale. The same operators can be applied to scalar fields on causal sets which are well approximated by curved spacetimes in which case they approximate square-(1/2)R where R is the Ricci scalar curvature. This can used to define an approximately local action functional for causal sets.
  Physical Review Letters 05/2010; 104(18):181301. · 7.37 Impact Factor