Kleppner

Hess H F, Kochanski G P, Doyle J M, Greytak T J, and Kleppner D 1986 Spin-polarized hydrogen maser Phys.Rev. A 34 1602-4... 

An interesting potential application of Rydberg atoms is as a far infrared (or microwave) detector, a notion first suggested by Kleppner and Ducas.37 The basic... 

D. Kleppner, M. G. Littman, and M. L. Zimmerman, in Rydberg States of Atoms of Molecules, eds. R.F. Stebbings and F.B. Dunning (Cambridge Univ. Press, Cambridge,... 

If one adopts McLennan s [78b] interpretation, then Eq. (21) is a realization of a standard theorem of Newtonian mechanics conservation of total energy = conservation of kinetic plus potential energy (see, e.g., Chap. 4 of Kleppner and Kolenkow, [80]). The reason is simple Coulomb electric force is central, then work is path independent, and total energy is function of position only. The time derivative of total energy is of course zero, as in Eq. (21). In this interpretation Qp and Qi are manifestations of kinetic energy. 

This is a well-known result from Newtonian mechanics see, for instance, Chap. 6 of Kleppner and Kolenkow [80]. 

D. Kleppner and R. J. Kolenkow, An Introduction to Mechanics, McGraw-Hill, 1978. 

Hess, H.F., Kochanski, G.P., Doyle, J.M., Masuhara, N., Kleppner, D. and Greytak, T.J. (1987). Magnetic trapping of spin-polarized atomic hydrogen. Phys. Rev. Lett. 59 672-675. 

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