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Dartmouth College

2010

Classical and quantum mechanics

Articles 1 - 3 of 3

Full-Text Articles in Physical Sciences and Mathematics

Information-Preserving Structures: A General Framework For Quantum Zero-Error Information, Robin Blume-Kohout, Hui Khoon Ng, David Poulin, Lorenza Viola Dec 2010

Information-Preserving Structures: A General Framework For Quantum Zero-Error Information, Robin Blume-Kohout, Hui Khoon Ng, David Poulin, Lorenza Viola

Dartmouth Scholarship

Quantum systems carry information. Quantum theory supports at least two distinct kinds of information (classical and quantum), and a variety of different ways to encode and preserve information in physical systems. A system’s ability to carry information is constrained and defined by the noise in its dynamics. This paper introduces an operational framework, using information-preserving structures, to classify all the kinds of information that can be perfectly (i.e., with zero error) preserved by quantum dynamics. We prove that every perfectly preserved code has the same structure as a matrix algebra, and that preserved information can always be corrected. We …


Results From Electrostatic Calibrations For Measuring The Casimir Force In The Cylinder-Plane Geometry, Q. Wei, D. A. R. Dalvit, F. C. Lombardo, F. D. Mazzitelli, R. Onofrio May 2010

Results From Electrostatic Calibrations For Measuring The Casimir Force In The Cylinder-Plane Geometry, Q. Wei, D. A. R. Dalvit, F. C. Lombardo, F. D. Mazzitelli, R. Onofrio

Dartmouth Scholarship

We report on measurements performed on an apparatus aimed to study the Casimir force in the cylinder-plane configuration. The electrostatic calibrations evidence anomalous behaviors in the dependence of the electrostatic force and the minimizing potential upon distance. We discuss analogies and differences of these anomalies with respect to those already observed in the sphere-plane configuration. At the smallest explored distances we observe frequency shifts of non-Coulombian nature preventing the measurement of the Casimir force in the same range. We also report on measurements performed in the parallel-plane configuration, showing that the dependence on distance of the minimizing potential, if present …


Quantum Information Encoding, Protection, And Correction From Trace-Norm Isometries, Francesco Ticozzi, Lorenza Viola Mar 2010

Quantum Information Encoding, Protection, And Correction From Trace-Norm Isometries, Francesco Ticozzi, Lorenza Viola

Dartmouth Scholarship

We introduce the notion of trace-norm isometric encoding and explore its implications for passive and active methods for protecting quantum information against errors. Beside providing an operational foundation to the “subsystems principle” [E. Knill, Phys. Rev. A 74, 042301 (2006)] for faithfully realizing quantum information in physical systems, our approach allows additional explicit connections between noiseless, protectable, and correctable quantum codes to be identified. Robustness properties of isometric encodings against imperfect initialization and/or deviations from the intended error models are also analyzed.