Beyond the long-wavelength approximation in electromagnetic Rydberg–Rydberg couplings

• Published in: Optics communications 2003-09, Vol.225 (1), p.123-130
• Main Authors: Parzyński, R., Sobczak, M.
• Format: Article
• Language: English
• Subjects: Atomic and molecular physics; Atomic properties and interactions with photons; Exact sciences and technology; Multiphoton ionization and excitation to highly excited states (e.g., rydberg states); Multiphoton ionization and excitation to highly excited states (eg, Rydberg states); Multipolar Hamiltonian; Photon interactions with atoms; Physics; Rydberg atoms
• ISSN: 0030-4018; 1873-0310
• DOI: 10.1016/j.optcom.2003.08.008

We give a method, to a great extent analytical, for calculating the high- n intrashell (Δ n=0) and intershell (Δ n≠0) Rydberg–Rydberg matrix elements of the full electric operator of the multipolar Hamiltonian for the atom – electromagnetic radiation interaction. Our method is an alternative to the recent approach of Komninos, Mercouris and Nicolaides [Phys. Rev. A 65 (2002) 043412] being predominantly a numerical one. Wherever a comparison has been possible, the two approaches are shown to give the same results. Within our approach we give a number of examples which should discourage the use of the electric-dipole approximation, and generally the long-wavelength approximation, in some problems of high- n Rydberg state physics.