Cambridge Theory of Condensed Matter Group -Critical Mass Grant

Lead Research Organisation: University of Cambridge
Department Name: Physics

Abstract

Describing the emergence of macroscopic behaviour from microscopic constituents is the central goal of condensed matter physics. Whether those constituents are electrons in a solid, atoms in a gas, or cells in tissue, the inherent complexity of this task calls for a three-pronged approach involving (1) realistic first principles calculations capable of numerical precision, (2) simplified models describing the transition to the macroscopic limit and (3) coarse-grained descriptions of that limit.

As described in this proposal, the Theory of Condensed Matter group pursues an integrated program of research in which this approach is applied to systems spanning quantum, soft, and living matter. These systems - including stem cells, pigment-protein complexes, and semiconductor-superconductor devices - are of fundamental scientific and technological importance, and their understanding may in time yield new therapies, opto-mechanical devices, solar cells, or computers. They are grouped into three themes:

The description of growth and form in living tissue and in programmable soft matter will be pursued by Profs Ben Simons and Mark Warner using both simplified microscopic models and continuum descriptions, in close contact with diverse experimental groups in Cambridge, USA, Holland and elsewhere.

The first principles investigations proposed by Profs Richard Needs and Mike Payne will establish all-purpose tools for the accurate calculation of the properties of both electronic and vibrational excited states in extremely large and complex systems. Such quantitative advances will prove invaluable for computational biology and designer materials.

The study of many body localisation is essential to understanding the non-equilibrium dynamics of large quantum systems. Prof Nigel Cooper and Drs Claudio Castelnovo and Austen Lamacraft will target experimentally realistic models of quantum devices and magnetic materials in close collaboration with project partners at Cornell and the Niels Bohr Institute, as well as more tractable model systems where more controlled calculations are possible.

Planned Impact

We have a long track record of delivering impact from our research. Much of our theoretical work is either (i) targeted at experimental systems, forming a natural complement to experiment and adding value by providing interpretation and validation; and/or (ii) aimed at providing information that is of real world use without the need for extensive experimental input; and/or (iii) although purely theoretical in its nature in the initial stages of research concerns systems which can be realized experimentally thus not only allowing our theoretical predictions to be tested but also opening up the longer term possibility that they can have a real world impact.

The group has a broad experience of technology transfer. Prof. Payne is a 'Departmental Champion' linking between the Cavendish Laboratory and Cambridge Enterprise and advising on technology transfer to those members of the Cavendish who are not familiar with the process. It is clear to anyone who has been involved in commercialisation that the demands on technology and software for successful technology transfer are significantly higher than those necessary to, say, publish a paper. The amount of work required to make the process successful is extremely high. Thus the examples of technology transfer from our group, detailed in the Pathways to Impact, not only indicate the quality of the science involved but indicate that we take the requirement to deliver impact from our work very seriously and are prepared to dedicate the time and effort necessary to make this process successful.

Direct beneficiaries of this proposal will be users of the ONETEP code; see Pathways to Impact.

Another direct impact to society and the economy is through the work of Prof. Simons, co-author of three patent applications through MRC Technology on the quantitative characterization of stem and progenitor cells for drug therapy, delivery and design.

New mechanics paradigms proposed by Prof.Warner et al. arise from their modelling and prediction of large shape changes, driven by light and heat, of materials with programmed response: The director determines direction and the order the magnitude of response. Spatial variation of both, in-plane or through the thickness, or both, is the route to Gaussian curved topography and hence haptics, braille displays, microfluidics, adaptive surfaces and optics, and micro-machines studied with collaborators in Eindhoven & USAF.

Many Body Localisation is a phenomenon of general relevance to technological applications of quantum mechanical systems, in line with the UK effort on quantum technologies. Moreover, Majorana systems and quantum spin liquids are of specific long-term interest to the quantum information industry, both to design novel (topological) type of quantum memories as well as quantum computation - just to give two examples. Our work will establish new connections between MBL and these emerging technologies, aiming for direct application and experimental validation through our network of experimental collaborators.

Experimental verification of MBL, for instance through collaboration with S.Davis at Cornell, will push the boundaries of cutting edge scientific techniques. Our results will directly interest the scientific instruments industry. The theoretical effort in this proposal will contribute to the design of analytical / numerical tool kits to interpret the data, which will feed into the next generation of commercial scientific instruments.

Indirect economic and societal impact will also be produced by the training of young scientists (graduate students and PDRAs). In particular, the proposal will give them the valuable opportunity to work in a context of close collaboration between theory and experiment. Some will remain in academia, forming the next generation of scientist in the UK and overseas, and some will seek other jobs, thus transferring knowledge and expertise to the industry.

Publications

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Allen AEA (2018) Harmonic Force Constants for Molecular Mechanics Force Fields via Hessian Matrix Projection. in Journal of chemical theory and computation

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Castelnovo C (2018) Dephasing with strings attached in Physical Review B

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Claeys P (2020) Maximum velocity quantum circuits in Physical Review Research

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Claeys P (2021) Quantum eigenstates from classical Gibbs distributions in SciPost Physics

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Claeys Pieter W. (2020) Maximum velocity quantum circuits in Phys.Rev.Res.

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Donnelly C (2020) Experimental observation of vortex rings in a bulk magnet in Nature Physics

 
Description We have made signicant advances in the theoretical understanding of topological systems and have enable experimentalists to develop experimental methods to create such systems using cold atoms.
Exploitation Route Topological systems may provide a way forward for quantum computing though it is very early days for this.
Sectors Digital/Communication/Information Technologies (including Software)

 
Title Data for "A tail-regression estimator for heavy-tailed distributions of known tail indices and its application to continuum quantum Monte Carlo data" 
Description Monte Carlo data and code for the associated paper. See the file 'description.txt' for detailed information about this dataset, including usage instructions. 
Type Of Material Database/Collection of data 
Year Produced 2019 
Provided To Others? Yes  
 
Title Data for "Evidence from quantum Monte Carlo of large gap superfluidity and BCS-BEC crossover in double electron-hole layers" 
Description Data for "Evidence from quantum Monte Carlo of large gap superfluidity and BCS-BEC crossover in double electron-hole layers" 
Type Of Material Database/Collection of data 
Year Produced 2018 
Provided To Others? Yes  
 
Title Data for "Stochastic sampling of quadrature grids for the evaluation of vibrational expectation values" 
Description Data for "Stochastic sampling of quadrature grids for the evaluation of vibrational expectation values" 
Type Of Material Database/Collection of data 
Year Produced 2018 
Provided To Others? Yes  
 
Title Data supporting "Molecules with dipoles in periodic boundary conditions in a tetragonal cell" 
Description All data for above paper. Contains Castep input and output files, and python scripts for calculating Ewald energies with their outputs. Also contains the figures from the paper. See the README.txt file for more information. 
Type Of Material Database/Collection of data 
Year Produced 2019 
Provided To Others? Yes  
 
Title Research data supporting "Predicting novel superconducting hydrides using machine learning approaches" 
Description  
Type Of Material Database/Collection of data 
Year Produced 2020 
Provided To Others? Yes  
URL https://www.repository.cam.ac.uk/handle/1810/303296
 
Description Expert Commentator on Naked Scientists Radio Show 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact Expert commentator on ultra cold matter.
Year(s) Of Engagement Activity 2019