Superfluid 3He at UltraLow Temperatures

Lead Research Organisation: Lancaster University
Department Name: Physics


Superfluid 3He has many exotic properties and provides a model system for investigating fundamental processes. It is the only accessible material which has absolute purity. It supports dissipationless flow of mass, spin and orbital angular momentum which give rise to a variety of macroscopic coherence phenomena. The coherent orbital and spin properties are described by vector order parameters which vary on very large length scales, limited only by the size of the experimental cell.

Our group specialises in novel cooling and measurement techniques at ultralow temperatures. We routinely cool superfluid 3He to record low temperatures where the few remaining thermal excitations are highly ballistic and the superfluid is essentially in its groundstate.

We plan a series of experiments to study fundamental properties of phase transitions and interfaces. The A-B phase transition at low temperatures occurs at a fairly large magnetic field of order 0.4Tesla. Using custom made superconducting solenoids we can accurately control the magnetic field profile to stabilise and manipulate the A-B phase interface. We will incorporate techniques to measure very small, femtowatt, energy dissipations when the interface moves. We will oscillate the interface to investigate how the different dissipation mechanisms depend on the velocity amplitude and the frequency. At low velocity/frequency the interface dissipates energy by scattering thermal excitations. At higher velocities/frequencies dissipation may occur by generating new excitations via processes analogous to particle production in high energy physics. We also expect the motion to induce interesting dynamics of the orbital textures on both sides of the interface.

The transition from A-phase to B-phase on cooling presents a long outstanding puzzle. According to standard theories the transition should not occur, even on astronomical timescales. Experiments show that the transition occurs quite readily. A possible explanation has been proposed based on `resonant tunneling' between metastable states. We will perform controlled experiments to test this. By forming a sharp magnetic field minimum we will shape the B-phase nucleating region into a bubble remote from the cell walls to eliminate surface mechanisms. According to the resonant tunneling model, the transition should only occur at particular temperatures and magnetic fields, giving a clear experimental signature.

We will construct an aerogel-based 3He cooling stage to access lower temperatures. We will directly cool, by demagnetization, the nano-network of solid 3He layers which coat the aerogel strands. These layers are in extremely good thermal contact with the surrounding liquid owing to rapid exchange. The stage will have an enclosed cavity to enable experiments on bulk superfluid 3He. The cavity will be completely surrounded by cold demagnetised aerogel to eliminate heat leaks. We believe it is possible to reach a new temperature regime where there are only a few remaining thermal excitations in the entire volume. We will use Nuclear Magnetic Resonance to simultaneously probe the bulk superfluid, the aerogel-confined fluid and the nanometer solid 3He layers. This will enable us to explore new phenomena in the extreme low temperature limit.

We will study ultralow temperature magnetic phase transitions in the solid layers. In the bulk B-phase we will investigate the Persistent Precessing Domain (PPD), a Bose-Einstein condensate of magnons. The free decay of the PPD may last several hours at the lowest temperatures. Under such extreme conditions, additional dissipation mechanisms may emerge, such as from ionisation tracks left by cosmic rays.

The research will lead to a better understanding of fundamental processes in quantum systems, phase transitions and phase interfaces, as well extending the capabilities of cooling technology.

Planned Impact

Superfluids are ideal systems to study fundamental physics. The lack of viscosity and thermal excitations can often simplify more complex phenomena such as in turbulence and phase transitions. Superfluid 3He has exotic properties associated with macroscopic spin and orbital coherence, and has analogies in superconductivity, particle physics and cosmology. Thus the scientific impacts spread far beyond the immediate fields of ultralow temperature physics and quantum fluids. Our research on cosmological analogues continues to inspire multidisciplinary activity in using condensed-matter experiments to probe cosmological processes. This proposal will promote further activity and potentially open new avenues for fundamental research. Our work on the superfluid A-B phase transition will test general properties of phase transitions and will probe new mechanisms. Likewise, our work on defect creation during interface collisions may produce synergies with many other fields. An understanding of the A-B interface will contribute towards a better understanding of quantum systems in general, with significant long term impacts as quantum systems play an increasingly central role in technology and industry.

The proposed research will benefit cryogenic industries. The use of dilution refrigerators and advance cooling techniques is continuing to grow. Through companies such as Oxford Instruments, ICE and Cryogenic Limited, the UK plays a leading role in the supply of cryogenic equipment. Sales of dilution refrigerators are continuing to increase rapidly, and there is a continuous demand for systems to reach lower and lower temperatures. Equally important is the thermometry needed to measure lower temperatures. The development of new cooling technology and thermometry is an integral part of our research. In the longer term, this fuels advances in commercial technology.

We are leading partners of the MICROKELVIN network which encourages commercial activity both here in Lancaster and in the wider European context. Commercial development is facilitated by Lancaster Cryogenics Limited, a new campus-based company, founded by members of our low temperature group to export knowledge and specialist ultra-low temperature equipment. Our department has a full-time industrial liaison officer who will help to better disseminate our work to industry and to exploit new opportunities for collaboration.

We disseminate our research far beyond our immediate beneficiaries thereby providing cultural enrichment for a wide audience. Our low temperature laboratory is showcased in our extensive outreach programs. We give many low temperature demonstrations, talks at local schools and public lectures. We have 1000+ visitors each year including perspective undergraduate students, parents and school children. Future research funding will allow us to maintain and strengthen this activity. We get extremely good feedback indicating that we have a significant impact, inspiring more students to take up University education, particularly in physics. The resulting higher levels of education benefit society as a whole.

Staff and students working on the project will develop a very broad range of skills including experiment design and construction, vacuum systems, materials processing and techniques for high magnetic fields. They develop generic skills in experimentation, data handling, measurement and analysis techniques. They also develop specialist skills in handling sophisticated research equipment, including state-of-the-art dilution refrigerators and nuclear demagnetization systems. A broad range of skills is attractive to all employment sectors.

Our group has a strong international reputation for building world class infrastructure, for performing novel experiments and for developing new techniques at the lowest temperatures. This adds to the overall profile of UK research and its reputation for pushing the boundaries of what is technically possible.


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Description The research funded on this grant spans blue skies discovery and the development of underpinning techniques. Although the award is still active we can already identify some key findings in both areas. First, we have made the serendipitous discovery that superfluid helium-3 can exhibit behaviour in a way not seen before in this or any other condensate system. We reported the completely unexpected experimental result that a coherent condensate may not be destroyed by a macroscopic object travelling through it at velocities which exceed the textbook criterion for breakdown set by Landau in the 1940's, and which has since stood as a primary cornerstone of our understanding in such systems. This was reported in Nature Physics as "Breaking the superfluid speed limit in a fermionic condensate" and is gaining considerable interest. Second, we have used our cooling expertise to set a new record low temperature for electrons in an on-chip device, a Coulomb Blockade Thermometer, (Nature Communications - "Nanoelectronic primary thermometry below 4 mK") and demonstrated a new technique for future advances (Scientific Reports - "On-chip magnetic cooling of a nanoelectronic device"). This is important as it facilitates new and growing areas of research in low temperature physics, nanoscience, quantum technologies and materials science. Third, we have cooled a nano-electro-mechanical (NEMS) device to the coldest ever temperature by immersing it in a quantum fluid (Scientific reports "Operating nanobeams in a quantum fluid"). This is important as it advances the quest for cooling mechanical devices into a regime where their motion is affected by quantum-mechanical behaviour. Fourth, we have solved a longstanding problem to discover the source of anomalous friction and dissipation when an interface between two different types of supposedly friction-free superfluids is set in motion. This work is submitted for publication.
Exploitation Route Our unexpected Landau critical velocity results have implications for a range of disciplines where the implications of super-critical flow must now be addressed. This includes all coherent condensate systems, from superconducting electrons, through bosonic and fermionic cold atomic gas condensates and even to the study of neutron stars where the core is held to be a neutron superfluid. We have validated a primary thermometer for the ultra-low temperature regime that is now available as a tool for other researchers to use in benchmarking their own cooling systems. This can also be used for future metrology of temperature, with potential commercial applications, for instance in solid-state quantum technologies that rely on the cryogenic environment. Our work on nano-electro-mechanical devices will be used in the push to discover (and exploit) how mechanical devices are affected by quantum mechanics. Our findings on anomalous friction on superfluid interfaces is important for all researchers looking at the properties of condensate systems.
Sectors Aerospace, Defence and Marine,Digital/Communication/Information Technologies (including Software),Education,Electronics,Energy,Environment,Manufacturing, including Industrial Biotechology

Description This research grant combines fundamental physics at the extremes of low temperature with the development of underpinning techniques, technology and instrumentation necessary to carry out the work. Our reputation for creating cutting edge instrumentation led to an InnovateUK/EPSRC sponsored award to develop a new cryo-free environment for quantum-enhanced sensors. This platform has now been brought to market by Oxford Instruments, with whom we continue to work with on new developments for the cold cryo-free environment. We have exhibited these advances at a Quantum Technology Showcase and InnovateUK exhibition. This is reported on elsewhere in my Researchfish portfolio. Our reputation for low temperature physics has also led to the filming of documentaries using our equipment. During the course of this grant the BBC documentary Everyday Miracles had segments filmed at Lancaster (reported in Engagement Activities in my Researchfish portfolio). The presenter Mark Miodownik recently returned to film again for another documentary segment for Magic Ingredients: Helium which will air later in 2017. Our work in thermometry at the lowest possible temperatures has led to us being selected as an end-user for the EU-wide H2020 project "Implementing the new Kelvin", crucially important for future temperature metrology across all sectors from research to commerce. We have trained personnel during this grant period. Outside of academia the destinations of our PhD students includes globally significant high-tech companies.
First Year Of Impact 2014
Sector Aerospace, Defence and Marine,Creative Economy,Education,Electronics,Healthcare
Impact Types Cultural,Societal,Economic

Description EPSRC Experimental Equipment Call
Amount £642,163 (GBP)
Funding ID EP/M028305/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 04/2015 
End 03/2016
Description EPSRC Fellowship
Amount £1,152,057 (GBP)
Funding ID EP/P024203/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 07/2017 
End 06/2020
Description EPSRC/TSB: Exploring the commercial applications of quantum technologies
Amount £244,457 (GBP)
Funding ID EP/M508354/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 05/2015 
End 04/2016
Description InnovateUK "Accelerating the commercial exploitation of quantum technologies"
Amount £248,000 (GBP)
Funding ID 70971-492147 
Organisation Innovate UK 
Sector Public
Country United Kingdom
Start 09/2016 
End 08/2017
Description Oxford Instruments 
Organisation Oxford Instruments
Country United Kingdom 
Sector Private 
PI Contribution This is/was an EPSRC/InnovateUK grant that brought together a team from the Physics Department at Lancaster University and a team from Oxford Instruments to work together on developing a cryofree ultra-low temperature platform for quantum-enhanced sensors. The proposal answered the call "Exploring the commercial applications of quantum technology". The Lancaster team explored the feasibility of new types of cryogenic solid-state magnetic sensors with greater sensitivity and functionality compared with traditional Superconducting Quantum Interference Devices (SQUIDs)
Collaborator Contribution The Oxford Instruments team explored the feasibility of creating a new cryogenic rig that would form a component part of new products utilising quantum-enhanced solid state devices for applications in sensing, imaging, information processing, etc.
Impact Prototype sensor has been made. Prototype cryogenic platform currently under construction. Academic paper submitted as joint submission between Lancaster University and Oxford Instruments. IP protection discussions ongoing. InnovateUK follow-on funding secured.
Start Year 2015
Description BBC documentary Secrets of the Super Elements: Helium 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Mark Miodownik came to film superfluid helium in our demonstration laboratory for a BBC documentary series: Secrets of the Super Elements
Year(s) Of Engagement Activity 2017
Description BBC filming for documentary Everyday Miracles 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Mark Miodownik came to film superconductivity demo's in our laboratory for a major BBC documentary series Everyday Miracles.
Year(s) Of Engagement Activity 2014
Description Innovate 2017 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact Innovate 2017 Exhibition at NEC Birmingham 8 & 9 November. Team from Lancaster University joined with a team from Oxford Instruments on a display stand to promote joint developments in new cryo-free low temperature technology.
Year(s) Of Engagement Activity 2017
Description NSF Grand Challenges in Quantum Fluids and Solids 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Invited to National Science Foundation policy meeting on Grand Challenges in Quantum Fluids and Solids to consult on future directions of this topic, in particular in the USA.
Year(s) Of Engagement Activity 2015