## Profile
Quantum Information Science
Quantum Optics
Quantum Electrodynamics ## Outputs
Title | Category | Date | Authors |
Refractive index of driven dense atomic gasesThe optical properties of an atomic gas, including
the dramatic reduction of the group velocity
of light associated with electromagnetically induced
transparency (EIT), usually grow with the density
of atoms in the medium. However, in high density
atomic gases, the resonant dipole-dipole interaction
(DDI) generates atomic correlations. These correlations
could significantly modify both linear and nonlinear
optical properties of the medium [1, 2, 3], which
may be beneficial for quantum information processing.
We develop a theory that describes the influence
of DDI on the optical properties of a dense gas
driven by classical control fields. Our method combines
dressed-states of quantum optics with nonequilibrium
many-body theory based on Feynman diagrams
and includes the effect of the atomic centerof-
mass-motion, which is relevant for the study of
different temperature regimes. This approach has
the advantage that the control fields are treated nonperturbatively. University of Calgary | Presentation | 2008-08-23 | I. Mahmoud, K. Marzlin, B. C. Sanders | Atomic many-body effects in the propagation of slow light through atomic gasesA quantum memory for photonic qubits is an essential tool
for quantum information processing because it would be vital
for long-distance quantum communication. A strong candidate
for quantum memories are atomic gases that exhibit electromagnetically
induced transparency (EIT). In such a medium the information about a
photon can be reversibly stored in form of a spin-wave.
The common quantum optical calculations suggest that ultracold gases
of high density would be most suitable for this task, but these theories
ignore the dipole-dipole interaction (DDI) between atoms that become
relevant at high densities. We have investigated the effect of DDI on
EIT and found significant differences between hot and ultracold atomic
gases. In a dense gas bosonic atoms close to condensation, DDI changes
the refractive index more significantly and also leads to collective
decoherence effects. Our theoretical approach combines dressed-states
of quantum optics with non-equilibrium many-body techniques
(Keldysh diagrams). University of Calgary | Presentation | 2008-04-20 | K. Marzlin, I. Mahmoud, B. C. Sanders |
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