Out of many atoms, one photon

Vladan Vuletić, Adam T. Black, James K. Thompson

N. Nayak, A. S. Majumdar, Vasileios Bartzis

We consider a micromaser model to study the influence of Dicke superradiance in the context of the one-atom maser. The model involves a microwave cavity into which two-level Rydberg atoms are pumped in pairs. We consider a random pump mechanism which allows the presence of at most one pair of atoms in the cavity at any time. We analyze the differences between the present system, called the Dicke micromaser, and an equivalently pumped conventional one-atom micromaser. These differences are attributed to the Dicke cooperativity in the two-atom system. We also show that the two-atom Dicke micromaser is equivalent to a one-atom cascade two-photon micromaser. With the introduction of a one-photon detuning, the present theory further describes a true two-photon micromaser. We discuss in detail the role of one-photon detuning in the mechanism of a one-atom two-photon micromaser. This leads us to point out that the two-atom cavity dynamics can be verified by a proper scaling of the results from an equivalent one-atom two-photon micromaser.

I Ashraf, A. H. Toor

We have developed a quantum theory of the micromaser for a pair of two-level atoms for the case of one- and two-photon transition coupling. We have studied the effect of co-operativity on the photon statistics for these systems for different coupling constant ratios. It is found that for equal coupling, our system of a two-atom, one-photon micromaser behaves like a double one-photon cascade micromaser. Similarly, for equal coupling, the photon statistics of the two-atom, two-photon micromaser reduces to that of a three-level, four-photon cascade micromaser.

Jürgen Volz, Weber, M., Schlenk, D. +3 more

Karl Otto Greulich

Throughout the development and confirmation of the photon concept, "Gedankenexperiments" have been invoked where a light source is attenuated until "only one photon is in the apparatus." Such a statement requires, however, knowledge on details of the light generation process, which were not known until the advent of true single-photon light sources such as isolated single atoms or molecules. Here, starting from a two atom light source, it is shown that probably multi-atom or multi-molecule light sources do not generate, even not in small fractions, antibunching photons and that attenuation down to one photon per time unit is not reliably possible. Thus, one of the strongest arguments in favour of the existence of single "photons" in free space, the accumulation time argument, which discusses the absorption of a single photon by a single atom or molecule, becomes questionable.