**Group Members**
**Publications**

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Introduction
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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.

*This page is maintained by
Robert Griffiths*

*Last modified November, 2013*.