Twenty three million square kilometres of northern-hemisphere land - one quarter of the total land area - is permafrost. This permanently frozen ground stores twice as much carbon as the atmosphere contains, with a significant fraction of this carbon as methane. Formation and thawing of permafrost is therefore a significant positive feedback in the climate system, removing greenhouse gas as Earth cools, and releasing it, in periods such as today, when the planet is warming. Permafrost also exerts a strong control on ecosystems and biodiversity, and it underpins human infrastructure (buildings and transport links) in many high-latitude settings. A significant body of research exists (and continues) into active permafrost processes in the modern environment, but assessing the long-term behaviour of permafrost has proved more difficult. We do not yet have a clear idea of how the temperature of high-latitude continental regions responds to changing of global climates through time, nor of the extent of permafrost in different climate states. Such information is important for future planning in today's permafrost regions, and for our general understanding of high-latitude carbon and climate systems. How do the major permafrost regions of the northern hemisphere respond to global climate change such as orbital variation or the progressive cooling of the planet during the Plio-Pleistocene? And what role might permafrost have in these amplifying these changes through its carbon feedbacks on climate? Here we propose to use carbonates formed in caves (speleothems) to assess the extent of permafrost in the world's largest area of permafrost - Siberia. Speleothems require water to form so, when the ground is frozen year-round, do not grow. The presence or absence of speleothems therefore constrains the extent of permafrost through time. We have been working on a sequence of three caves which stretch from the modern edge of the permafrost-free zone near Irkutsk at 52oN, northwards through patchy permafrost and to the edge of continuous permafrost at 60oN. This work has yielded a detailed reconstruction of the permafrost history during the last 450 ka, showing thawing of the permafrost in each warm interglacial period in the south. In the north (60oN) the permafrost remained stable except during the interglacial period 390-430 ka ago when global conditions were warmer than present. We propose to continue the reconstruction of the permafrost history beyond the ~500 ka limit of the U-Th dating method in these caves, and to add a fourth cave in the centre of the continuous permafrost region at 64oN. Using a newly proven U-Pb dating ability, we will date periods of speleothem growth during the Plio-Pleistocne to assess the time, as the planet cooled after the warmth of the Pliocene, that permafrost conditions initiated in Siberia. And we will constrain the changing extent of permafrost during the variable climates of the Pleistocene. By comparing these records with information about climate elsewhere, we will learn how the high latitude northern continents respond to global climate change, particularly during periods warmer than today. To understand how the cave temperatures in each location related to annual mean temperatures above the caves will require a campaign of monitoring in our study caves. We will conduct this work in close collaboration with Russian colleagues from the Russian Academy of Sciences and the well-established Siberian caving community. We will also use our connections in Russia to ensure that new information we learn is provided to stakeholders in regions that will be impacted by changing permafrost in the future.

One of the regions where current global warming is most pronounced is Siberia and the Russian Far East (SRFE). Inconveniently, this is also one of the regions with least coverage of climate records in international databases. As a consequence, it is extremely difficult to analyse and understand the spatial and temporal variations of climate change in SRFE that can provide context for past changes and current warming trajectories, and data are inadequate for syntheses that can aid evaluation of simulations of past climate-an important way to assess how well models perform at projecting the future, whether it be the impact on communities and ecosystems of forest fires or the fate of carbon currently stored in soils and peatlands. The lack of records from SRFE partly reflects that there are few well established, multi-year international collaborations between Russian institutes and international partners. While scientists at Russian institutes have access to large datasets and field sites and have high-quality staff conducting laboratory analyses, they often have less access to the latest analytical approaches and data quality control protocols-or indeed the language fluency currently required for high-impact international publications and data syntheses. This can generate an imbalance of influence within projects and lead to one-sided and/or short-term scientific interactions that do not have long-term direction and coherence. We will address both the science and science culture issues via a network of researchers from the UK and six institutes of the Russian Academy of Sciences in SRFE. Partners in this network have already expressed a strong interest to work together and pool resources to (1) synthesise existing data, (2) learn new methods, and (3) together create new high-quality records of climate and environmental change in this and future research projects. Our network is called DIMA ("Developing Innovative Multi-proxy Analysis"), because we will use multiple new approaches to get climate information from sediment records (proxies) to reconstruct climate change. Our partnership-building and collaboration have several aims. First an extant dataset that described past vegetational change, which has not yet reached an international audience, will be analysed by the DIMA groups to create value-added features (e.g., data formulated for climate-vegetation modelling exercises) prior to publication. Second, we will collect samples to apply a method new to this region for reconstructing past temperatures from insect remains in lake sediments; this will be underpinned by UK-based training of Russian collaborators in the use of the latest laboratory and statistical procedures during a month-long visit of three colleagues from SRFE to the UK. It will involve collecting modern reference samples and generating a high-quality long temperature record from western Siberia as proof-of-concept for an expanded programme. Project leader van Hardenbroek is a specialist in this field. The two selected Russian Project Partners have considerable experience in organising field campaigns and laboratory analysis and will provide the necessary personnel, support and infrastructure. The new data and the experience gained during this project will place the DIMA team in a competitive position to apply for larger collaborative project; the highly motivated team will be geared up to generate long-term climate records across SRFE, produce a high-quality regional temperature synthesis, and develop collaborations with, for example, groups using data compilations to explore climate-vegetation model performance (co-I Edwards current collaboration). This proposal addresses the UK government's expressed need for developing and maintaining strong science ties with key countries, including Russia and strengthening international collaborations outside Europe post-Brexit.

Classically electrons in a three-dimensional solid can change their momentum in all possible directions. However, electrons in semiconductors can be manipulated so that they are constrained to move in lower dimensions. One of the perfect examples of such a system is a semiconductor heterostructure of GaAs/AlGaAs forming a plane of electrons, only a few nanometer thick, at its junction where electrons possessing quantised energy and freedom to change momentum in the plane. Such remarkable ensemble of non-interacting electrons is known as the two-dimensional electron gas (2DEG). The electrons in a 2DEG system are highly mobile and at low temperatures their motion is mainly scattering free due to the reduction in the interaction with lattice vibrations (phonons) and there is little impurity scattering. When the 2D electrons are electrostatically squeezed to form a narrow, 1D channel whose effective size is less than the electron mean free path for scattering then quantum phenomena associated with the electrons becomes resolved. In this situation, the energy of 1D electrons becomes quantised and discrete levels are formed. At a low carrier concentration of electrons, if the potential which is confining the 1D electrons is relaxed then electrons can arrange themselves into a periodic zig- zag manner forming a Wigner Crystal, named after Wigner who first predicted such a phenomenon in metal in 1936. Recently the distortion of a line of electrons into a zig-zag and then into two separate rows of electrons was observed and associated rich spin and charge phases. A very subtle change in confinement can result in two rows emerging from a zig-zag state which indicates that there is a narrow range where wavefunctions separate and form entangled states. Entanglement is a remarkable phenomenon in which a change in state of one electron will introduce a change in state of another. This amazing property forms the basis for quantum information processing with practical consequences related to quantum technologies, which will be investigated in this proposal. Another most important aspect of my Fellowship proposal is investigating the zig-zag regime or relaxed 1D system in search of fractional quantum states in the absence of a magnetic field. In the presence of a large magnetic field the energy of a 2DEG is quantized to form Landau levels which gave rise to two celebrated discoveries of the Integer and fractional quantum Hall effects in 1980 and 1982 respectively. Such unexpected revelations then pose a question whether fractional quantised states in the absence of any magnetic field in any lattice or topological insulators could ever be observed? However, there were no reports of observations of any fractional states without a magnetic field until the recent discovery of fractional charges of e/2 and e/4 arising from the relaxed zig-zag state in a Germanium-based 1D system. The proposal is inspired by this and the recent experimental finding of non-magnetic self-organised fractional quantum states in tradition GaAs based 1D quantum wires, which was completely unanticipated. The research aim is to introduce new insights, and new aspects of quantum physics, by exploiting the interaction effects in low-dimensional semiconductors by manipulating electron wavefunctions in a controllable manner to allow technological exploitation of basic quantum physics. The major challenges to be investigated: spin and charge manipulation, demonstrating electron entanglement and detection, mapping self-organised fractional states and their spin states, controlled manipulation and detection of hybrid fractional states and establishing if they are entangled. This research proposal opens up a new area in the quantum physics of condensed matter with the generation of Non-Abelian fractions which can be used in a Topological Quantum Computation scheme.

As the global climate warms, thawing permafrost may lead to increased greenhouse gas release from Arctic and Boreal ecosystems. Scientists agree that this permafrost-climate feedback is important to the global climate system, but its magnitude and timing remains poorly understood. The overall aim of COUP is to use detailed understanding of landscape-scale processes to improve global scale climate models. Better predictions of how permafrost areas will respond to a warming climate can help us understand and plan for future global change. In recent years much scientific progress has been made towards understanding the complex responses of permafrost ecosystem to climate warming. Despite this, large challenges remain when it comes to including these processes in global climate models. Permafrost ecosystems are highly variable and studies show that very detailed field investigations are needed to understand complexities. Because global scale models cannot run at such high-resolutions, we propose an approach where local landscape-scale field studies and modelling are used to identify those key variables that should be improved in global models. We will carry out careful field studies and high-resolution modelling at field sites covering all pan-Eurasian environmental conditions. The system understanding gained from this will then be used to (1) scale key variables so they are useful for global models and (2) improve a new global climate model. In the final step, the improved global climate models will be run to quantify the impact of thawing permafrost on the global climate. Datasets produced in COUP will be freely available online so that they can be used by other scientists and help improvement of all global climate models. COUP is designed to maximise synergies with ongoing projects. Much of the needed data and system understanding was generated in other research programmes.