Many Body Localisation in the Solid State for Finite Temperature Quantum Computing
Lead Research Organisation:
University of Aberdeen
Department Name: Chemistry
Abstract
This proposal builds on the exciting discovery of an exotic insulator-insulator transition in the oxyarsenide CeMnAsO1-xFx (x = 0.035 - 0.075). Such temperature driven metal-insulator and insulator-insulator transitions, in which the resistivity changes by orders of magnitude over a very narrow temperature range, have attracted considerable interest from both theoretical and experimental researchers and have novel applications such as Resistance Random Access Memory (RRAM). The origin of the insulator-insulator transition in CeMnAsO1-xFx is not yet established but preliminary results suggest that this transition could be the first observation of many body localisation (MBL) in the solid state. The most significant characteristic of MBL systems is that below a transition temperature (TMBL) they become perfect insulators, exhibiting zero electronic conductivity. The MBL phase also acts as a quantum memory. Moreover, the localisation of MBL systems can be used to protect quantum memory allowing the tantalising possibility of performing topological quantum computation at finite temperatures. We will perform the vital measurements to confirm the MBL phase. If verified, we will be the first group in the world to report MBL in the solid state. The discovery of a material exhibiting MBL in the bulk would be transformative, as the MBL phase has the potential to revolutionise technological applications involving quantum sensors and computing, offering non-classical system performance. It would also create a new experimental research field that will allow the realisation of fundamentally new forms of quantum matter through non-equilibrium transitions.
| Description | The research built on the exciting discovery of an exotic insulator-insulator transition in the oxyarsenide CeMnAsO1-xFx (x = 0.035 - 0.075). Such temperature driven metal-insulator and insulator-insulator transitions, in which the resistivity changes by orders of magnitude over a very narrow temperature range, have attracted considerable interest from both theoretical and experimental researchers and have novel applications such as Resistance Random Access Memory (RRAM). Preliminary results had suggested that the exotic insulator-insulator transition could be the first observation of many body localisation (MBL) in the solid state. The most significant characteristic of MBL systems is that below a transition temperature (TII) they become perfect insulators, exhibiting zero electronic conductivity. The MBL phase also acts as a quantum memory. Moreover, the localisation of MBL systems can be used to protect quantum memory allowing the tantalising possibility of performing topological quantum computation at finite temperatures. Several samples of CeMnAsO0.95F0.05 were synthesised and analysed by a range of physical measurements (variable temperature resistvity, Hall resistivity, Seebeck effect, AC transport and heat capacity). From these measurements we evidenced five signatures of MBL in each sample as described below: 1. Variable temperature resistivity measurements showed there was a transition to a perfect insulator below TII. 2. Variable temperature Hall resistivity measurements showed that the electrons are trapped below the transition. 3. At the same time a colossal Seebeck effect is observed as the charge mobility of the electrons decreases rapidly with temperature. 4. AC transport measurements demonstrate that there are slow dynamics at a temperature, T*, slightly higher than TII so that there is a critical slowing of dynamics at T*, which would correspond to a continuous dynamical phase transition consistent with the theoretical predictions for MBL. 5. There is no thermodynamic signature in variable temperature heat capacity measurements so that the transition is a purely dynamic phenomenon. These results combined, highly suggest TII is a result of a many body localisation of electrons. This is the first time so many signatures of MBL have been reported in the bulk. The discovery of a material exhibiting MBL in the bulk is transformative, as the MBL phase has the potential to revolutionise technological applications involving quantum sensors and computing, offering non-classical system performance. It will also create a new experimental research field that will allow the realisation of fundamentally new forms of quantum matter through non-equilibrium transitions. Further theoretical and experimental research is warranted to explore this phase further. |
| Exploitation Route | This research will create a new research area that will allow the realisation of fundamentally new forms of quantum matter through non-equilibrium transitions. So many signatures of MBL have never been observed in the bulk before. This discovery will be timely and exciting as bulk materials exhibiting MBL will have transformative impact as they can be exploited to host quantum bits with reduced decoherence and hence drive future quantum technologies. I would envisage scientists form fields such as chemistry, physics, materials science and quantum computing to further investigate this phase and see if it's possible to be observed in other materials. This research is still at a very fundamental stage and further interdisciplinary research will be needed to exploit the properties of MBL fully. |
| Sectors | Chemicals,Digital/Communication/Information Technologies (including Software),Education,Electronics |
| Description | We collaborated with Professor A Walsh to elucidate the electronic structure of CeMnAsO1-xFx |
| Organisation | Imperial College London |
| Country | United Kingdom |
| Sector | Academic/University |
| PI Contribution | We provided preliminary data for the electronic structure calculations and led the discussion. |
| Collaborator Contribution | Aron Walsh's group performed electronic structure calculations on CeMnAsO1-xFx which gave further insight into the exotic insulator-insulator transition. |
| Impact | We are in the final stages of rewriting a paper based on the referees comments. |
| Start Year | 2021 |
| Description | School visits |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | No |
| Geographic Reach | Local |
| Primary Audience | Schools |
| Results and Impact | We gave a workshop to several schools illustrating the research by the solid state chemistry group at Aberdeen in novel energy and quantum materials. |
| Year(s) Of Engagement Activity | 2021 |