Quantum Enhanced Superfluid Technologies for Dark Matter and Cosmology

The QUEST-DMC programme seeks to answer some of the most fundamental questions facing modern physics: What is the physics of the early universe? What is the nature of dark matter? What is the origin of the matter-antimatter asymmetry? We will focus on the investigation of two core building blocks of early universe cosmology, which may be fundamentally linked; the identity and nature of dark matter and the physics of phase transitions. By combining a macroscopic quantum system, superfluid helium-3 (3He), with state-of-the-art quantum technologies we will pioneer a new dark matter search experiment with unprecedented discovery potential. In parallel we will use the unique properties of superfluid 3He as a quantum simulator of phase transitions in the early universe.

Dark Matter plays a vital role in the evolution of the universe, for example, it played a central role in the formation of structure in early universe and today plays a key role in stopping galaxies flying apart. The focus of dark matter studies and searches to date has been on Weakly Interacting Massive Particles (WIMPs) whose predicted mass range is broadly speaking between 10-1000 times that of the proton. The direct, indirect and collider searches for this dark matter candidate to date have been extensive but ultimately unsuccessful. There is a strong motivation to widen the search.

The fact that the universe only consists of matter with no anti-matter requires explanation, since it is reasonable to assume that matter and anti-matter were produced in equal quantities in the Big Bang. This implies that during the evolution of the universe a process took place that dynamically generated the asymmetry between matter and anti-matter. Models linking the dynamics of dark matter with the generation of the matter/anti-matter asymmetry naturally predict a mass scale of dark matter that is close to the mass of the proton, of order 1 GeV/c2, suggesting an alternative target mass range to the standard WIMP. This project will create and operate a detector for the direct search of dark matter with sub-GeV masses using superfluid helium-3 as a target with world-leading sensitivity.

The second major component of this project is a detailed investigation of the physics of phase transitions. Phase transitions are a key prediction of the symmetry-breaking paradigm of the Standard Model of particle physics in extreme conditions, such as those of the early universe or inside neutron stars. A first-order phase transition produces a characteristic gravitational wave signature and forms a leading motivation for gravitational wave searches. According to our current understanding of the mechanism of phase transitions, called nucleation theory, no gravitational waves are predicted in Standard Model. If gravitational waves are detected and their origins can be linked to a phase transition in the early universe then this would be evidence of Physics beyond the Standard Model of particle physics, with high impact on our understanding of fundamental physics. It is critical that the physics of phase transitions is tested so that experiments such as the approved European Space Agency mission LISA due for launch in 2034 are fully exploited. This project will do this using phase transitions between different quantum vacua in superfluid 3He, under controlled conditions, as a quantum analogue.

This programme brings together the frontiers of cosmology, ultralow temperatures and quantum technology.
Both experiments exploit the unique properties of superfluid helium-3, cooled to 100 microkelvin above absolute zero. It will rely on a range of state-of-the-art superconducting quantum sensors, and nanofabricated structures such as nanobeam resonators, and structured nanoscale confinement. Future developments in quantum technologies will generate further improvements in sensitivity and range of the sub-GeV dark matter search in the longer term.

This proposal details interlinked research programmes that address two fundamental open questions in cosmology; what is the nature of dark matter and what will be the observable consequences of phase transitions in the early universe? To address these questions we will employ sensors exploiting recent developments in Quantum Technologies operated in low noise, ultra-low temperature environments. The results obtained will be compared with theoretical models developed within QUEST-DMC, impacting on a wide range of beneficiaries beyond academia. This summary details who those beneficiaries are and what the positive impacts on them will be.
Who will benefit?
Our fundamental research drives forward the development of state-of-the-art research capacity. At RHUL, the UK Centre for Superconducting and Hybrid Quantum Systems (UK-CSQS), Superfab, is dedicated to the development of quantum device technology through the application of fundamental phenomena based on superconductivity. At LU the Quantum Technology Centre contains state-of-the-art nanofabrication facilities. Both facilities are integral in the quantum technology supply chain. Developments in instrumentation measurement systems directly benefit the strong UK scientific instruments industry, especially those focussed on cryogenics, nanoscience and superconducting technologies, such as Oxford Instruments Nanoscience.
In the longer term, applications in health care and environmental monitoring will benefit from advances in sensor technology or measurement techniques, developed in this work, with positive societal as well as economic impacts.
The key demographics that are being targeted by our public engagement strategy are: primary and secondary school students (in particular encouraging girls to develop an interest in physics to try to address the under-representation of women in physics at all levels); teachers of GCSE Science and A-level Physics (providing a teacher with inspirational material has a multiplier effect on the audience reached); undergraduate students; the physics interested public in the local communities of the four partner institutions, and nationally through participation in Science Festivals; and finally we have plans to target the adult low science capital demographic who would not normally attend a science event.

How will they benefit?
The benefit to the scientific instrument industry will be through: direct collaboration on potential commercial products exploiting new technologies; knowledge exchange through consultation with the expertise of QUEST-DMC; and via the export of highly trained manpower to industry. The research described in this proposal combines new techniques in ultralow temperature physics, new measurement techniques and devices, and a robust confrontation between theory and experiment. Individuals trained in these skills and expertise, equipped with rigorous scientific methodology, are an important resource enhancing economic competitiveness.

The public will be made more prepared for the disruptive technologies that will be driven by the current quantum revolution. We will raise awareness through a range of public engagement activities detailed in the pathways to impact, organised in partnership with schools, professional bodies, the Ogden Trust, the Smallpeice Trust, the Stephen Hawking Foundation and the network of university public engagement and outreach teams that are part of QUEST-DMC.

What will be done to ensure that they benefit?
The accompanying pathways to impact details the specific measures and activities put in place to ensure that we maximise the opportunities for impact. Long-standing partnerships with National Measurement Institutes (NPL, PTB, MIKES), international dark matter consortia, the European Microkelvin Platform, Quantum Technology hubs and academic partners around the world provide additional avenues to amplify the impact via arrangements for technology and knowledge exchange.