Report on EPSRC Symposium Workshop on Quantum Simulations 2009

The EPSRC Symposium Workshop on Quantum Simulations was held in the Department of Mathematics at the University of Warwick from the 24th to the 28th of August 2009 inclusive. 42 delegates from 14 different counties attended the event and 32 delegates gave lectures about their recent work in the area of quantum simulation. The scope of this meeting was to bring together the two complementary approaches that are currently used to study quantum phenomena, namely (i) the study of paradigmatic model and their universal characteristics and (ii) the study of realistic models and their system specific features. To develop a more constructive dialogue between these approaches we brought together a group of scientists with interest focusing in a restricted number of themes. Both lectures focused on the simulation of universal characteristics and lectures focused on the system specific characteristics were given by the delegates on the five general themes outlined below:  Surface and Edge phenomena have been discussed in more idealized systems by Slevin, Oswald, Hoyos while several issues involving the chemical specificity of the surface have been covered by Teobaldi, Hanke and Corni.  Charge transport in biophysical systems (mostly DNA) was discussed in the form of paradigmatic models by Wells, Chakraborty, Domingues-Adame and with the tools of computational chemisty by Das Pemmaraju, Skourtis, and Kleinekathoefer.  Single molecule (or quantum dot) electronics was discussed using phenomenological models by Lambert and Logan while a more chemical view was proposed by Luo and Pecchia.  Models to study localization and quantum phase transition have been presented by Miranda, Dobrosavljevic, Schreiber, Rodriguez-Gonzalez. Some instances of localized transport described at the atomic level have been proposed by MacKenzie, Papadopoulos and Cheung.  The theory of electron and exciton transfer in organic materials was discussed by Fratini and Hannewald while models with a different level of system specificity were proposed by Van Dongen, Beljonne and May. The program of the conference with the full list of participants and the slides of their presentation is available on the following web page: http://www.warwick.ac.uk/go/quantsim09 Ample time for discussion was scheduled between the presentations and between the sessions of the meeting. Besides many technical clarifications and discussions around specific topics the following general considerations emerged from the scientific interaction within the meeting:  The community of scientists interested in the quantum simulations of specific systems can and should benefit from the use of simplified models for the analysis of their data and for the rationalization of results across different systems. A collaboration with mathematical physicists may be helpful in increasing the impact of purely computational works. In the communication of their results to an interdisciplinary audience computational scientists should be encouraged to outline the accuracy of the calculations and their effective cost.  The community interested in the study of model systems can and should collaborate with the computational chemistry and physics community to validate its models against realistic computational data and to facilitate the comparison with experiments. In the communication of results deriving from model system to an interdisciplinary audience they should be encouraged to detail the rationale behind the choice of a model and the reason for excluding the alternatives. The necessity of merging different perspectives was evident in all themes presented above and it can be easily illustrated by the case of charge transport in DNA. A number of very accurate evaluations of the DNA electronic Hamiltonian and dynamics have been presented and they tend to be associated with an oversimplified modelling of the charge transport (typically within Marcus model). More sophisticated models, for example based on transfer matrices or explicit wavefunction propagation, tend to be built on Hamiltonians that are too simple to allow a direct comparison with the experiment. A very similar problem is encountered in the study of charge transport in quantum dots or in bulk organic materials.

On the basis of the animated discussion between scientists with very different background we believe that this workshop achieved its goals of informing the different communities involved in the study of quantum simulations stimulating the development of new research collaborations across communities.

The organizers:

Rudolf A. Römer Alessandro Troisi