Andrew Fisher

Understanding coherent spin dynamics in rare-earth spin systems (with Gabriel Aeppli and others) The theory of quantum entanglement, especially in condensed-phase systems; Theory of quantum information processing and decoherence (with Sougato Bose and others); The theory of electrical conduction through molecules and nanostructures, especially inelastic and local heating effects (with David Bowler, Andrew Horsfield and others); Theory of scanning tunnelling microscopy, especially lIETS (Inelastic Electron Tunnelling Spectroscopy - with Werner Hofer and Geoff Thornton). Contact details: Office: 5C3, LCN, UCL Tel: +44 (0)20 7679 1378 Ext: 31378 Fax: +44 (0)20 7679 0595 Email: andrew.fisherucl.ac.uk

Research Interests

I have wide research interests in theoretical nanoscience.  I am particularly interested in the impact of quantum mechanics on the dynamics of nanostructures – for example, the flips of small clusters of spins, or the flow of current-carrying electrons though a molecule or an atomic-scale wire – and the extent to which interactions with other degrees of freedom can modify or damp out these quantum mechanical effects.  The consequences of this work range from quite applied questions – how could one use quantum mechanics to process information, or make a transistor from a single molecule?– to rather fundamental ones – what is the macroscopic limit of quantum mechanics?  I use a mixture of analytical and computational techniques and I like to work closely with experimentalists; several of my research students and postdoctoral research fellows are closely involved with experimental projects.

Other activities

I lecture the undergraduate course PHAS2222 Quantum Physics in the UCL Department of Physics and Astronomy, where I am also Director of Postgraduate Studies and Postgraduate Tutor.  I am currently the chair of the UK’s collaborative computational project on surface science, CCP3, and a member of the management teams for the Interdisciplinary Research Collaborations (IRCs) in Nanotechnology and Quantum Information Processing.  I also coordinate the information systems within the LCN.

Recent publications

The signature of a chemical bond in the conductance between two metal surfaces.  W.A. Hofer and A.J. Fisher, Phys. Rev. Lett. 91 036803 (2003). 
[available for download from the publisher's site]
This paper outlines the long-sought relationship between the characteristic electrical and mechanical effects as an incipient chemical bond is formed between a scanning probe tip and a metal surface.

Vibrational inelastic scattering effects in molecular electronics. H. Ness and A. J. Fisher. Proc. Nat. Acad. Sci. 102 8826-8831 (2005).  DOI: 10.1073/pnas.0500389102. 
[available for download from the publisher's site]
This paper describes our development of a scattering-theory technique capable of accounting for the distortions occurring in a molecule as charge passes through it, and compares our method with other approaches to the problem.

The transfer of energy between electrons and ions in solids. A. P. Horsfield, D. R. Bowler, H. Ness, C. G. Sánchez, T. N. Todorov, and A. J. Fisher. 
Reports on Progress in Physics 69 1195-1234 (2006). DOI:10.1088/0034-4885/69/4/R05. 
[available for download from the publisher's site]
This is a review covering a range of approaches to the problem of how energy is transferred between ions and electrons in solids and nanostructures, including a description of our own CEID (Coherent Electron-Ion Dynamics) method.