Novel Experiments in Multiphase Superfluid 3He at Ultralow Temperatures

Lead Research Organisation: Lancaster University
Department Name: Physics

Abstract

Superfluids, superconductors and Bose condensed dilute gases are extremely interesting since their constituent atoms form coherent ground states, in which the behaviour of the whole system is correlated, leading to macroscopic quantum phenomena.However, superfluid 3He is unique due to its multi-component order parameter. The 3He atoms form pairs which have both spin and orbital angular momentum. The mass, spin and orbital motions each exhibit coherent quantum behaviour giving rise to a whole range of exotic properties. This added complexity allows superfluid 3He to exist in two very different coherent phases, A and B, depending on the temperature and magnetic field.We are able to cool superfluid 3He to temperatures where virtually all atoms are paired, so we have an almost pure quantum state. By applying a suitably shaped magnetic field profile we can stabilise different phases in different regions, with various geometries including an isolated bubble of B-phase surrounded by A-phase. The bubble geometry will allow us to study fundamental processes, which might otherwise be influenced by walls, such as phase nucleation, thermal transport and turbulence.The A-B interface is a coherent structure separating two highly coherent phases. The order parameter must make a complex pirouette in crossing from one phase to the other, matching-up smoothly the mass, spin and orbital degrees of freedom. This unique system gives us an entre into a wide range of new physics. It is clearly an interesting system in its own right. However, it also provides a model for less accessible systems. For example, it is the nearest thing we have in the laboratory to a cosmological brane (equivalent structures in space-time). By colliding two A-B boundaries, we can simulate brane-annihilations in the laboratory. These are of fundamental interest to the braneworld scenarios of cosmology.By immersing aerogel in 3He we can study the superfluid phases in the dirty limit generated by the disorder induced by the nanometre sized silica strands in the aerogel. Furthermore, when we immerse the aerogel in superfluid, a few atomic layers of 3He atoms are adsorbed onto the silica strands to make a substantial solid 3He component in the helium-aerogel system. The solid 3He is highly magnetic and is in intimate contact with the fluid. This provides a unique opportunity for using magnetic cooling techniques on the solid and the near perfect thermal contact to cool the superfluid. The solid layers around the silica strands form a system of 3He-nanotubes which also have potential for revealing new exciting physics. We intend to develop a 3He-aerogel cooling stage to study both the solid 3He-nanotubes and to cool the superfluid to new a low temperature regime where there are essentially no thermal excitations over macroscopic volumes of the liquid.Recently, we have also found that superfluid 3He provides a particularly useful tool for studying quantum turbulence at low temperatures. Quantum turbulence is essentially a tangle of quantum vortex lines (line defects around which the superfluid circulation is quantised). Quantum turbulence has close analogues with classical turbulence but is much simpler, due to the quantised vortices and lack of viscosity, and might therefore provide better insights to understanding turbulence in general. We plan to use highly sensitive calorimetric techniques, which we have developed earlier, to measure the energy decay of quantum turbulence in the zero temperature limit, providing better information on fundamental decay mechanisms.Finally we are using these experiments to pilot the development of a new form of the highly sensitive quartz resonator, custom-designed to maximise its interaction with superfluid 3He at the lowest temperatures. We hope that this will replace the currently ubiquitous vibrating wire resonator (also developed at Lancaster) as the standard low temperature quantum fluids sensor/thermometer.

Publications

10 25 50
 
Description 1) We have demonstrated that the thin (nanoscale) solid layers of 3He adsorbed on strands of aerogel immersed in superfluid 3He at microkelvin temperatures are highly magnetic and are able to form the basis for a new cooling method which will take superfluid 3He into a new low temperature regime where the number of excitations in the superfluid is vanishingly small, in other words far into the "pure condensate" regime.

2) We have developed a series of highly sensitive quartz resonators for sensing quasiparticle excitations in superfluid 3He which has allowed us to build sophisticated quasiparticle video cameras for imaging vortices in the superfluid. We have gained enough experience from this work that we should be able to improve the imaging system beyond the 5x5 pixels currently used to a higher resolution system capable of resolving single vortices and their evolution in real time. These devices are the coldest imaging systems (at ~ 100 microkelvin) ever used.
Exploitation Route 1) The nuclear cooling of nanostrands of solid 3He on aerogel will allow other quantum fluids groups to cool 3He into the pure condensate region.

2) The vortex imaging system will allow the whole quantum turbulence community a unique insight into the dynamics of this phenomenon. (Classical turbulence is intractable since the governing Navier-Stokes equations have as yet no universal solution. Quantum turbulence with its simpler structure of an ensemble of identical singly quantized vortices (effectively an "atomic model" of turbulence) can throw light on the otherwise inaccessible classical phenomenon which has economic consequences across the whole of human activity from blood flow to weather.)
Sectors Aerospace, Defence and Marine,Energy,Manufacturing, including Industrial Biotechology,Other

 
Description Both the cooling findings and the imaging progress will feed inot the general techniques of ultralow temperature physics. This impacts especially UK industry as the UK has a large fraction of the World output in equipment designed to work in this sector.
First Year Of Impact 2016
Sector Aerospace, Defence and Marine,Other
Impact Types Economic

 
Description EPSRC
Amount £935,212 (GBP)
Funding ID EP/I028285/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 10/2011 
End 09/2015
 
Description EU FP7 Infrastructure Project MICROKELVIN 2009-2014 
Organisation Aalto University
Department Department of Applied Physics
Country Finland 
Sector Academic/University 
PI Contribution This was an FP7 Infrastructure Network, where Lancaster was one of the three access-giving hubs. Thus we played a senior role in the consortium with GRP acting as chairman of the governing council.
Collaborator Contribution We undertook joint research projects with the other partners and provided experimental access to our facilities (paid for by FP7) for partnmers and others to run experiments at Lancaster.
Impact Many publications already listed under EPSRC grants.
Start Year 2009
 
Description EU FP7 Infrastructure Project MICROKELVIN 2009-2014 
Organisation BlueFors Cryogenics
Country Finland 
Sector Private 
PI Contribution This was an FP7 Infrastructure Network, where Lancaster was one of the three access-giving hubs. Thus we played a senior role in the consortium with GRP acting as chairman of the governing council.
Collaborator Contribution We undertook joint research projects with the other partners and provided experimental access to our facilities (paid for by FP7) for partnmers and others to run experiments at Lancaster.
Impact Many publications already listed under EPSRC grants.
Start Year 2009
 
Description EU FP7 Infrastructure Project MICROKELVIN 2009-2014 
Organisation European Organization for Nuclear Research (CERN)
Department Physics Department
Country Switzerland 
Sector Academic/University 
PI Contribution This was an FP7 Infrastructure Network, where Lancaster was one of the three access-giving hubs. Thus we played a senior role in the consortium with GRP acting as chairman of the governing council.
Collaborator Contribution We undertook joint research projects with the other partners and provided experimental access to our facilities (paid for by FP7) for partnmers and others to run experiments at Lancaster.
Impact Many publications already listed under EPSRC grants.
Start Year 2009
 
Description EU FP7 Infrastructure Project MICROKELVIN 2009-2014 
Organisation Heidelberg University
Department Department of Physics and Astronomy
Country Germany 
Sector Academic/University 
PI Contribution This was an FP7 Infrastructure Network, where Lancaster was one of the three access-giving hubs. Thus we played a senior role in the consortium with GRP acting as chairman of the governing council.
Collaborator Contribution We undertook joint research projects with the other partners and provided experimental access to our facilities (paid for by FP7) for partnmers and others to run experiments at Lancaster.
Impact Many publications already listed under EPSRC grants.
Start Year 2009
 
Description EU FP7 Infrastructure Project MICROKELVIN 2009-2014 
Organisation Leiden University
Department Leiden Institute of Physics
Country Netherlands 
Sector Academic/University 
PI Contribution This was an FP7 Infrastructure Network, where Lancaster was one of the three access-giving hubs. Thus we played a senior role in the consortium with GRP acting as chairman of the governing council.
Collaborator Contribution We undertook joint research projects with the other partners and provided experimental access to our facilities (paid for by FP7) for partnmers and others to run experiments at Lancaster.
Impact Many publications already listed under EPSRC grants.
Start Year 2009
 
Description EU FP7 Infrastructure Project MICROKELVIN 2009-2014 
Organisation NEEL Institute
Country France 
Sector Public 
PI Contribution This was an FP7 Infrastructure Network, where Lancaster was one of the three access-giving hubs. Thus we played a senior role in the consortium with GRP acting as chairman of the governing council.
Collaborator Contribution We undertook joint research projects with the other partners and provided experimental access to our facilities (paid for by FP7) for partnmers and others to run experiments at Lancaster.
Impact Many publications already listed under EPSRC grants.
Start Year 2009
 
Description EU FP7 Infrastructure Project MICROKELVIN 2009-2014 
Organisation Physikalisch-Technische Bundesanstalt
Country Germany 
Sector Public 
PI Contribution This was an FP7 Infrastructure Network, where Lancaster was one of the three access-giving hubs. Thus we played a senior role in the consortium with GRP acting as chairman of the governing council.
Collaborator Contribution We undertook joint research projects with the other partners and provided experimental access to our facilities (paid for by FP7) for partnmers and others to run experiments at Lancaster.
Impact Many publications already listed under EPSRC grants.
Start Year 2009
 
Description EU FP7 Infrastructure Project MICROKELVIN 2009-2014 
Organisation Royal Holloway, University of London
Department Department of Physics
Country United Kingdom 
Sector Academic/University 
PI Contribution This was an FP7 Infrastructure Network, where Lancaster was one of the three access-giving hubs. Thus we played a senior role in the consortium with GRP acting as chairman of the governing council.
Collaborator Contribution We undertook joint research projects with the other partners and provided experimental access to our facilities (paid for by FP7) for partnmers and others to run experiments at Lancaster.
Impact Many publications already listed under EPSRC grants.
Start Year 2009
 
Description EU FP7 Infrastructure Project MICROKELVIN 2009-2014 
Organisation Slovak Academy of Sciences
Department Institute of Experimental Physics SAS
Country Slovakia 
Sector Academic/University 
PI Contribution This was an FP7 Infrastructure Network, where Lancaster was one of the three access-giving hubs. Thus we played a senior role in the consortium with GRP acting as chairman of the governing council.
Collaborator Contribution We undertook joint research projects with the other partners and provided experimental access to our facilities (paid for by FP7) for partnmers and others to run experiments at Lancaster.
Impact Many publications already listed under EPSRC grants.
Start Year 2009
 
Description EU FP7 Infrastructure Project MICROKELVIN 2009-2014 
Organisation University of Ottawa
Department Department of Physics
Country Canada 
Sector Academic/University 
PI Contribution This was an FP7 Infrastructure Network, where Lancaster was one of the three access-giving hubs. Thus we played a senior role in the consortium with GRP acting as chairman of the governing council.
Collaborator Contribution We undertook joint research projects with the other partners and provided experimental access to our facilities (paid for by FP7) for partnmers and others to run experiments at Lancaster.
Impact Many publications already listed under EPSRC grants.
Start Year 2009