John Imbrie

Professor & Associate Chair

P. O. Box 400137
Dept. of Mathematics
325 Kerchof Hall

Research Areas
Mathematical Physics
Publications/Research

Branched polymers and dimensional reduction, Annals of Mathematics, 158 (2003), 1019-1039 (with D. Brydges). arXiv:math-ph/0107005

On Many-Body Localization for Quantum Spin Chains, http://arxiv.org/pdf/1403.7837.pdf

Research Interests

My research interests lie in rigorous methods in probability and statistical mechanics, especially as relates to critical phenomena, where the length over which local effects are felt tends to infinity. Examples from probability and physics include the self-avoiding walk, branched polymers, spin systems, random Schroedinger operators, disordered systems, and quantum field theory (theories of elementary particles). The mathematics of functional integrals plays an essential role in the analysis of such systems. The renormalization group method organizes the analysis into a sequence of more tractible problems associated with an increasing sequence of length scales. Certain questions in physics can best be addressed with a theorem-oriented approach, especially if heuristic methods give conflicting indications. One example is the Ising model in a random magnetic field, which had conflicting heuristic descriptions with different predictions for the existence of long-range order in three dimensions. By proving that the ground state of the system did posess long-range order, I was able to settle this question definitively. The idea of dimensional reduction, in which certain d-dimensional models are connected with related (d-2) dimensional models, is an attractive concept which originates from a supersymmetry of the problem. Although my work on the random-field Ising model showed that dimensional reduction does not work there, my recent work with Brydges shows that dimensional reduction works for branched polymers, and this leads to exact results on that problem, including critical exponents in 2, 3, and 4 dimensions.

Education

  • Bachelor of Arts (BA), Harvard University
  • Master of Arts (MA), Harvard University
  • Doctor of Philosophy (PhD), Harvard University

Research Projects

  • GAANN 2009
    • Project sponsored by U.S. Department Of Education - Post Secondary Ed.
    • 08/15/2009 - 08/14/2012