The aim of the project is to carry out theoretical research on Rydberg atoms in crossed electric and magnetic fields and to thereby gain a greater understanding of the fundamental connection between the quantum and semiclassical dynamics for complex multi-dimensional systems. An electron excited to a Rydberg or continuum state of an atom in externally applied crossed electric and magnetic fields exhibits classically chaotic motion due to the competition between the external and internal fields. The corresponding quantum spectra are extremely rich and complex. This experimentally accessible system exhibits chaos in 3 dimensions whereas most of the chaotic systems studied so far have been 2 dimensional. Several new experiments are being performed to measure the
photoabsorption and photoionisation spectra of atoms in crossed electric and magnetic fields for a variety of field strengths. These spectra will be calculated theoretically for the first time using new approaches based on both ab initio quantum methods and semiclassical periodic theory. In addition new experiments on rubidium in static external fields are being performed, which involve the excitation and detection of Rydberg wavepackets and which give us a further tool to investigate the quantum manifestations of classically non-integrable systems. Numerical methods will be used to solve the time dependent Schrodinger equation to calculate and analyse the behaviour of Rydberg wavepackets in crossed electric and magnetic fields.