Raizen started his scientific career in theoretical
particle physics in 1984 with
Steven Weinberg. In 1985, Raizen moved into
experimental physics where he began his work with Jeff Kimble. In his graduate work, Raizen was instrumental in one of the first experiments that measured
squeezed states of light and also observed the Vacuum
Rabi splitting in the optical domain. While at NIST, Raizen developed a miniature
linear ion trap which has become the basis for
quantum information with trapped ions. At the University of Texas, Austin, the research program in the Raizen Group uses
laser cooling and trapping of neutral atoms to study fundamental problems. They observed dynamical localization in the momentum of atoms, the quantum suppression of
chaos. In other experiments, Raizen and his group investigated quantum transport of atoms in an accelerating
optical lattice. They studied the loss mechanism during the acceleration due to
quantum tunneling. For short times, they found a deviation from the
exponential decay law in the survival probability. This short-time deviation from exponential decay was then used to suppress or enhance the decay rate, effects known as the
Quantum Zeno effect or Anti-Zeno effect. Raizen and his group built two experiments with
Bose–Einstein condensate in
rubidium and
sodium. They developed a system for the study and control of quantum statistics of atoms and quantum entanglement. The system includes a condensate in an optical box trap together with single atom detection. In a separate experiment, they demonstrated coherent slowing of
supersonic beams. Using an atomic paddle, a slow monochromatic beam of ground state
helium was produced. In a different approach, pulsed
magnetic fields were used to stop
paramagnetic atoms and molecules. To further cool these particles, Raizen and his collaborators introduced the concept of a one-way barrier, or one-way wall, which is used to accumulate atoms or molecules in
optical tweezers. This method was realized experimentally by the Raizen Group in December 2007. This cooling method is a physical realization of informational cooling, originally proposed by
Leó Szilárd in 1929. This proposal used the concept of information entropy to resolve the paradox of
Maxwell's demon. Together, these methods enable the trapping and cooling of atoms that span most of the
periodic table and paramagnetic molecules. In 2009, Raizen and his group built an experiment to study
Brownian motion of a bead of glass held in
optical tweezers in air. In 1907,
Albert Einstein published a paper in which he considered the instantaneous velocity of
Brownian motion and showed that it could be used to test the
equipartition theorem, one of the basic tenets of statistical mechanics. In this paper, Einstein concluded that the instantaneous velocity would be impossible to measure in practice due to the very rapid randomization of the motion. In the spring of 2010, the Raizen Group measured the instantaneous velocity of a Brownian particle in air. In 2014, they completed the same measurement in water and
acetone. The velocity data was used to verify the
Maxwell-Boltzmann velocity distribution, and the
equipartition theorem for a Brownian particle. These methods of controlling atoms were used by Raizen and collaborators to separate
isotopes with high efficiency. The experiment demonstrated enrichment of
lithium-7 to a purity over 99.95% in a single pass. The separation method is termed magnetically activated and guided isotope separation (MAGIS). One application of the work will be to produce enriched isotopes for medicine at a non-profit entity, The Pointsman Foundation, where Raizen serves as chairman of the board. ==Personal life==