Ultracold Gases far from Equilibrium: Fluctuations in time-dependent Geometries
Lead Research Organisation:
Newcastle University
Department Name: Mathematics and Statistics
Abstract
Intensive research over the last 15 years has shown that one can cool atoms in a gas by suitable use of magnets and light to a tiny fraction above absolute zero, the temperature at which all motion freezes. At such a low temperature, atoms suddenly experience an 'identity crisis', and are coerced into behaving identically - what is scientifically termed 'coherently'. Because these 'ultracold' atoms are almost stationary, they can actually become sensitive 'measuring devices' of effects they would otherwise essentially not feel, such as gravity, or magnetic fields. Suitable devices have been constructed to take advantage of this, and are known as 'atom interferometers'. In such devices, a group of trapped, very cold atoms is split into two smaller groups of approximately equal size in physically-separated locations, and then subsequently joined together again. A study of the properties of the atoms after they are joined reveals important information about changes in phenomena taking place when they were separated (e.g. changes in the strength of gravity between the two separated locations). Such a 'measuring device' has essentially two variants, depending on whether the atoms were originally stationary or moving, with each scheme having its own benefits and shortcomings. In order to take full advantage of such devices, one should develop a detailed understanding of the physical processes that take place in such systems, and this project intends to make significant advances in this area.A detailed description of such systems is complicated by the fact that at the typical temperatures where most current experiments take place, only some of the atoms behave 'coherently', with the rest of the atoms behaving in a random fashion, just like atoms in the air around us. Moreover, our ability to control the motion of atoms appears to be enhanced in thin long geometries, but this significant benefit is partly counterbalanced by the tendency of such geometries to destroy the 'coherent' nature of the system; the latter is due to fluctuations (in the phase of the system) which arise as a fundamental consequence of quantum mechanics, the theory which describes the microscopic world. Any theoretical model attempting to describe such experiments accurately should take account of these issues.The main aims of this project are two-fold: (i) firstly, to perform an in-depth study of fundamental physical mechanisms which may restrict the accuracy of such devices. (ii) Secondly, this project addresses the crucial question of how feasible it is to produce in a controlled manner a beam of atoms which maintain their coherence, even though they are actually moving, a topic of great current interest. Although there are numerous related theoretical studies in the literature, this work is unique in that it combines essential features that have to date only been implemented in independent studies: (i) firstly, this study is performed under realistic conditions, in which only some of the atoms behave coherently, and includes the full dynamics of both 'coherent' and 'random' atoms and their interactions. (ii) Moreover, additional complications (phase fluctuations) arising from the fact that these systems are very thin and long are also treated by advanced (stochastic) techniques, which are naturally 'built into' the approach mentioned above, with such a generalised theory solved numerically for the first time in the present work.Motivated by recent pioneering experiments which remain only partly understood, we use computers to study how the properties of the atoms are affected upon changing various parameters of the system, such as geometry, size and temperature, and we further investigate related issues in moving atoms.
People |
ORCID iD |
Nikolaos Proukakis (Principal Investigator) |
Publications
Cockburn S
(2012)
Ab initio methods for finite-temperature two-dimensional Bose gases
in Physical Review A
Cockburn S
(2011)
Comparison between microscopic methods for finite-temperature Bose gases
in Physical Review A
Cockburn S
(2011)
Fluctuating and dissipative dynamics of dark solitons in quasicondensates
in Physical Review A
Cockburn S
(2011)
Quantitative study of quasi-one-dimensional Bose gas experiments via the stochastic Gross-Pitaevskii equation
in Physical Review A
Cockburn S
(2010)
Matter-Wave Dark Solitons: Stochastic versus Analytical Results
in Physical Review Letters
Gallucci D
(2012)
Phase coherence in quasicondensate experiments: An ab initio analysis via the stochastic Gross-Pitaevskii equation
in Physical Review A
Henkel C
(2017)
Cross-over to quasi-condensation: mean-field theories and beyond
Henkel C
(2017)
Cross-over to quasi-condensation: mean-field theories and beyond
in Journal of Physics B: Atomic, Molecular and Optical Physics
Märkle J
(2014)
Evaporative cooling of cold atoms at surfaces
in Physical Review A
Description | This project was aimed at obtaining an improved, more detailed, understanding of the behaviour of ultracold gases - a system of interest to both experimentalists and theorists - as it enables the pure study of quantum effects in a relatively large system, in which cold atoms behave 'in unison', exhibiting interesting phenomena below a certain characteristic temperature; this is particularly true in experiments in which the dominant processes occur in only one or two dimensions, which enhances the role of fluctuations. Understanding, and harnessing, such non-equilibrium processes in the presence fluctuations is of significant importance in potential devices based on such systems. This work provided a detailed framework for understanding such systems, and was tested against experiments from the key international groups, generating specific scientific outcomes. |
Exploitation Route | If the applications mentioned above (atom chips, atom lasers, atom interferometers) were to become more broadly accessible outside academia in the future (e.g. to industrial sector related to quantum technologies), then this work could be seen as having an indirect contribution to such devices. The outcomes of this research are relevant to both experimentalists and theorists dealing with ultracold atoms and their dynamics, and indirectly might help optimize future devices. |
Sectors | Education Other |
URL | http://www.jqc.org.uk/people/nick-proukakis/29/ |
Description | Other research groups have benefited from the outcomes of this grant, implementing, or building upon our techniques. It has also led to discussions with experimentalists, who are themselves engaged in discussions with industry about the possibility of forming new, or enhancing existing quantum technologies. The research led to the compilation of a computing manual for future researchers. |
First Year Of Impact | 2013 |
Sector | Education,Other |
Description | IoP Student Fund |
Amount | £250 (GBP) |
Organisation | Institute of Physics (IOP) |
Sector | Learned Society |
Country | United Kingdom |
Start | 05/2011 |
End | 06/2011 |
Description | Royal Society Travel Award |
Amount | £1,100 (GBP) |
Organisation | The Royal Society |
Sector | Charity/Non Profit |
Country | United Kingdom |
Start | 05/2010 |
End | 06/2010 |
Description | Comparison of stochastic techniques for finite temperature Bose gases |
Organisation | University of Ulm |
Country | Germany |
Sector | Academic/University |
PI Contribution | Presentation of joint collaborative work at German Physical Society meeting DPG Tagung 14 March 2011, Dresden |
Start Year | 2009 |
Description | Visiting Academic |
Organisation | University of Queensland |
Country | Australia |
Sector | Academic/University |
PI Contribution | Invited to visit the University of Queensland to discuss joint research interests. This resulted in one joint publication to date, and an additional book chapter in preparation. Moreover, 3 members of that group have since visited Newcastle University for periods of 1-12 weeks for related discussions, |
Start Year | 2010 |
Description | Visiting Professorhsip |
Organisation | Eberhard Karls University of Tübingen |
Country | Germany |
Sector | Academic/University |
PI Contribution | Invited visit to discuss possible theoretical-experimental joint research opportunities |
Start Year | 2011 |
Description | Visiting Professorhsip |
Organisation | Queen's University |
Country | Canada |
Sector | Academic/University |
PI Contribution | Inivited to visit Queen's University, Kingston, Canada to discuss related research issues. |
Start Year | 2010 |
Description | Visiting Professorhsip |
Organisation | University of Toronto |
Country | Canada |
Sector | Academic/University |
PI Contribution | Invited to visit Toronto University to discuss related research issues |
Start Year | 2010 |
Description | 'Modelling Quasi-condensate atom chip experiments' and 'Decay of macroscopic excitations in atomic condensates' |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Participants in your research and patient groups |
Results and Impact | Two research talks given in consecutive weeks at the University of Tubingen, Germany. Very strong interfacing with key international research group; led to subsequent research publication. |
Year(s) Of Engagement Activity | 2011 |
Description | Dark soliton dynamics in atomic Bose condensates |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Participants in your research and patient groups |
Results and Impact | Invited talk during my visiting professorship at Toronto: 2010 May 11 Canada Department of Physics, University of Toronto. Prmotion of my research to a borad community |
Year(s) Of Engagement Activity | 2010 |
Description | Dark soliton dynamics in atomic condensates |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Participants in your research and patient groups |
Results and Impact | Invited seminar during my academic visit there 2010 Jul 6 Australia School of Mathematics and Physics, The University of Queensland, Brisbane. Borad disemmination of research findings |
Year(s) Of Engagement Activity | 2010 |
Description | Finite temperature properties of fluctuating trapped atomic quasi-condensates |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Participants in your research and patient groups |
Results and Impact | Invited seminar Nov 18 U.K. School of Physics and Astronomy, University of Birmingham. Making research connections within the UK |
Year(s) Of Engagement Activity | 2011 |
Description | How to model ultracold Bose gases at nonzero temperatures |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Participants in your research and patient groups |
Results and Impact | 3-hour graduate teaching/research seminar 2011 Mar Austria Atominstitut, Vienna University of Technology. Education of pre-PhD students at an international institute |
Year(s) Of Engagement Activity | 2011 |
Description | Modelling Finite Temperature Bose Gases |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Participants in your research and patient groups |
Results and Impact | 2009 Dec Germany Joint Atomic & Condensed Matter Physics Seminar Series Universities of Stuttgart, Tuebingen and Ulm (Tuebingen) . INternational profile raising |
Year(s) Of Engagement Activity | 2009 |
Description | Modelling quasi-1D Bose gases via the Stochastic Gross-Pitaevskii equation |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Participants in your research and patient groups |
Results and Impact | Invited research seminar 2011 Mar 2 U.K. School of Physics and Astronomy, University of Leeds. Interfacing with colleagues from broader research interests. |
Year(s) Of Engagement Activity | 2011 |
Description | Modelling quasi-1D Bose gases with the stochastic Gross-Pitaevskii equation |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Regional |
Primary Audience | Participants in your research and patient groups |
Results and Impact | Invited Departmental Seminar: Durham Atomic and Molecular Physics ( ATMOL) Group seminar, UK (16th March 2011 ). Disemmination of novel research results |
Year(s) Of Engagement Activity | 2011 |
Description | Non-Equilibrium Ultracold Bose Gases |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Participants in your research and patient groups |
Results and Impact | Invited departmental seminar 2010 Feb 18 U.K. Department of Physics, University of Southampton. Discussions with colleagues |
Year(s) Of Engagement Activity | 2010 |
Description | Soliton propagation in trapped quantum gases |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Participants in your research and patient groups |
Results and Impact | INvited seminar during my visiting professorship 2010 23 Apr Canada Department of Physics, Engineering Physics and Astronomy, Queen's University, Kingston. International research networking |
Year(s) Of Engagement Activity | 2010 |
Description | Stochastic Modelling of Quasi-condensates |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Participants in your research and patient groups |
Results and Impact | Invited Seminar at: 2011 18 July Germany Department of Physics, University of Freiburg. Research links with key german UNiversity; led to research visit to the UK |
Year(s) Of Engagement Activity | 2011 |
Description | Ultracold Trapped Atoms: A fully controllable condensed matter system |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Participants in your research and patient groups |
Results and Impact | Invited departmental colloquim 2010 Mar 25 Greece Dept. of Applied Mathematics and Theoretical Physics, National Technical University of Athens. Interfacing with international colleagues of different specialisations. |
Year(s) Of Engagement Activity | 2010 |
Description | Ultracold Trapped Atoms: A fully controllable macroscopic quantum system |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Participants in your research and patient groups |
Results and Impact | Invited departmental seminar 2010 Mar 18 Greece Department of Physics, University of Athens. interfacting with non-experts in my field |
Year(s) Of Engagement Activity | 2010 |