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The Quantum Theory Group at Carnegie-Mellon combines research on quantum foundations with research on quantum information and quantum computation. An early contribution of this group to the theory of quantum computation and information was the proposal by Griffiths and Niu, Phys. Rev. Lett. 76 , 3228 (1996), for eliminating two-qubit gates in the final Fourier transform of Shor's factorization algorithm. At present our research is focused on understanding the flow of information in quantum circuits, entanglement of two or more quantum systems and how it gives rise to teleportation and dense coding, the security of quantum cryptographic schemes, and understanding decoherence in information-theoretic terms.

The consistent histories approach to quantum theory was initiated at Carnegie-Mellon in 1984 by Griffiths, and was subsequently developed and refined by him and by Gell-Mann, Hartle, and Omnès. It provides a fully consistent procedure for integrating probability theory into quantum mechanics without invoking measurements, and gets rid of numerous conceptual difficulties without using hidden variables or other modifications of the standard Hilbert-space formulation of quantum theory. It has been applied to problems in cosmology, quantum optics, and quantum information, as well as to issues in the foundations of quantum mechanics. More information can be found in the Consistent Histories page. The book Consistent Quantum Theory (Cambridge University Press 2003) by Griffiths provides a detailed introduction to the subject, and analyzes various long-standing paradoxes of quantum theory, such as two-slit interference and Einstein-Podolsky-Rosen correlated states, without any need for mysterious long-range influences or other ghostly effects. Current work on quantum foundations focuses on explaining various aspect of the consistent histories approach, comparing it to other interpretations of quantum mechanics, countering the claims that quantum mechanics is contextual or nonlocal, and preparing teaching materials that provide a coherent and paradox-free exposition of quantum theory for those who are studying it for the first time.

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This page is maintained by Robert Griffiths
Last modified November, 2013.