Robert Bluhm does research in several areas of theoretical physics.
As a graduate student at Rockefeller University in New York and as a
postdoc at Indiana University, Robert worked on string theory,
which is a quantum theory that attempts to unify all of the known
fundamental forces into one theory. String theory is important because it
is so far the only known consistent quantum theory that includes gravity.
Robert also does work on problems in atomic physics that focus on the correspondence between classical and quantum mechanics. This involves characterizing and studying the evolution of Rydberg wave packets that are produced when a short laser pulse excites an atom. These wave packets follow the classical motion of a particle moving on a Keplerian orbit, but they also display quantum interference effects that cause the wave packets to collapse and revive. It is this behavior that is currently being studied by Robert and some of his students at Colby.
More recently, Robert has been examining tests of the CPT theorem in
atomic systems. The CPT theorem is a powerful result holding for
local relativistic quantum field theories of point particles in flat spacetime.
It states that such theories must be invariant under the combined operations
of charge conjugation C, parity reversal P, and time reversal T. Experiments
comparing the anomalous magnetic moments of the electron and positron can
place tight limits on CPT violation. The combination of the theoretical proof
of CPT invariance and high-precision tests in experiments has triggered
investigations of possible CPT violation as a candidate signature for new
physics beyond the standard model, such as string theory.
Robert has been using a new theoretical framework that describes possible
CPT violating effects in the
context of quantum electrodynamics to examine experiments on that test CPT.
These include
electron-positron and proton-antiproton experiments in
Penning traps as well as proposed spectroscopic
comparisons of trapped hydrogen and antihydrogen.
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rtbluhm@colby.edu
