Interaction of radiation with atoms

Mauro Antezza

Interaction between atoms and thermal radiation

Brijesh Kumar

A two-level atom interacting with a single mode of quantized electromagnetic radiation is discussed using a new representation in which the atom and the radiation are unified into a single canonical Bose field. At the twice resonance , when the frequency of the original radiation is twice the atomic transition frequency (ω = 2 ), the emergent unified field in the non-interacting atom–field system resembles a free radiation of frequency . This free emergent radiation is further shown to exist in the presence of an interaction which looks similar to the atom–field interaction in the dipole approximation. The one-photon correlation and the population inversion are discussed as the possible means of observing the emergent radiation. The entanglement properties of the emergent radiation are also discussed.

Daniel F. Walls, Gerard J Milburn

Christopher J. Foot

Abstract To describe the interaction of a two-level atom with radiation we shall use a semiclassical treatment, i.e. the radiation is treated as a classical electric field but we use quantum mechanics to treat the atom. From the theory of the interaction with radiation, we will be able to find the conditions for which the equations reduce to a set of rate equations that describe the populations of the atomic energy levels (with a steady-state solution). In particular, for an atom illuminated by broad band radiation, this approach allows us to make a connection with Einstein’s treatment of radiation that was presented in Chapter 1; we shall find the Einstein B coefficient in terms of the matrix element for the transition.

Daniel F. Walls, Gerard J Milburn

O. N. Gadomskiĭ, A. G. Glukhov

The forces acting on interacting moving atoms exposed to resonant laser radiation are calculated. It is shown that the forces acting on the atoms include the radiation pressure forces as well as the external and internal bias forces. The dependences of the forces on the atomic spacing, polarization, and laser radiation frequency are given. It is found that the internal bias force associated with the interaction of atomic dipoles via the reemitted field may play an important role in the dynamics of dense atomic ensembles in a light field. It is shown that optical size resonances appear in the system of interacting atoms at frequencies differing substantially from transition frequencies in the spectrum of atoms. It is noted that optical size resonances as well as the Doppler frequency shift in the spectrum of interacting atoms play a significant role in the processes of laser-radiation-controlled motion of the atoms.