Quantum optics, laser physics, nonlinear optics and quantum thermodynamics.

Quantum Optics: The phenomena of squeezing dealing with the reducing of quantum mechanical uncertainty than that of a minimum uncertainty state. Its study in atomic system known as spin squeezing.
Laser Physics : The physics of micromaser and microlaser, the one-atom laser. Study of possibilities of generating Fock states of radiation fields.
Nonlinear Optics: Slow light using multiwave mixing and self induced transperancy.
Quantum thermodymics: The role of quantum mechanics in the conventional thermodynamics. Its demonstration by adding a one-atom laser to an Otto cycle engine