Atoms in crossed fields: a new experimental approach

Abstract

We describe a novel experiment on Rydberg atoms in crossed electric and magnetic fields, recently performed at Imperial College. The novelty resides in a combination of a crossed-field geometry with a time-gated detection technique, by which separation of the circularly polarized components is now achieved. The importance of achieving such a separation and the new opportunities it opens up are explained. By this approach, a map of the diamagnetic Stark patterns is obtained. The data exhibit interesting behaviour in that the hydrogenic and non-hydrogenic groups within the n-shell now become distinguishable. Their evolution as a function of field strength brings out the difference between linear and quadratic effects. The levels with a quadratic dependence on electric field strength eventually invade and dominate the spectrum. We surmise that the trend from order to chaos is different in crossed fields from the trend in the diamagnetic limit. We comment on further theory required to clarify this point. Our observations extend up to and slightly above the saddle-point energy.

Core effect on the diamagnetic spectrum of barium Rydberg states

“…The spectral lines in the same n manifold shift to higher energy when the magnetic field gets stronger and stronger, due to the diamagnetic interaction. According to the Pauli quantization scheme [25], the energy shift of p states can be estimated by…”

“…Lu et al [15] presented a densitometer mapping of diamagnetic effects on barium and strontium and discussed the effects of perturbation states (4d5p 1 P 1 for strontium and 5d8p 1 P 1 for barium) on the intensity and spacing of principle series spectra. The group of Connerade in Imperial College contributed much to the investigations of the diamagnetic effect of alkaline earths [21][22][23][24][25], giving a lot of inspiration to our work on the core scattering of the quadratic Zeeman spectrum of barium [26].…”

From nuclear to meso systems: how small is simple and how large is complex?

“…Unfortunately, no experiments so far have been able to uncover clear evidence of the failing of one or other approach to the interpretation, the most complete test being probably the study of Rydberg atoms in crossed electric and magnetic fields with full separation of circular polarisations, performed at Imperial College [14,15] and analysed at the Queens University, Belfast [16,17]. In short, issues relating to the field of 'Quantum Chaology' belong to the subject of 'Dynamics at the Nanoscale' (DYSON).…”

Photodetachment ofH−by a short laser pulse in crossed static electric and magnetic fields

“…Consequently for more than a quarter century (up to the present) experimentalists and theorists have been investigating atomic Rydberg spectra in external fields, including in particular the interesting case of crossed static electric and magnetic fields [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36]. These latter investigations for the crossed field case include studies of motional Stark effects on Rydberg atom spectra in a magnetic field [2], of novel, highly excited resonance states [3,6,7,8,10,12,14,17,24], of circular Rydberg states [9], of Rydberg wave packets in crossed fields ...…”

“…High resolution studies of atomic Rydberg states in the presence of external static electric and magnetic fields have proved to be exceedingly fruitful for the investigation of atomic dynamics because, owing to the large radial extent and weak binding of atomic Rydberg levels, the effects of external static fields are much more significant for Rydberg levels than for atomic ground or low-lying excited states [1]. Consequently for more than a quarter century (up to the present) experimentalists and theorists have been investigating atomic Rydberg spectra in external fields, including in particular the interesting case of crossed static electric and magnetic fields [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36]. These latter investigations for the crossed field case include studies of motional Stark effects on Rydberg atom spectra in a magnetic field [2], of novel, highly excited resonance states [3,6,7,8,…”