2D polaritons for optoelectronic devices and networks

Lead Research Organisation: UNIVERSITY OF EXETER
Department Name: Physics and Astronomy

Abstract

The rate of information growth corresponds to an annual increase of 19%, reaching 100 zettabytes by the end of 2022, and novel optoelectronic tools are required for fast information processing. With perpetual generation and flow of information around, increasing the bit rates of devices that process information is imperative for sustainable future. Typically, optical signals - photons - are sent over fibre links, and that is how majority of internet traffic flows. However, photons do not interact with each other, unless they couple to a medium in which they propagate. One way to act is converting light into electronic signals, and processing signals with conventional electronics. However, in this case Ohmic losses reduce energy efficiency and processing speed is defined by electronic timescales. A distinct way to process light relies on strong light-matter coupling. When photons are coupled strongly to optical transitions and particles in semiconductors, they become hybrid light-matter particles - polaritons. Polaritons acquire nonlinearity and allow for information processing in an all-optical way. The efficiency of this process largely depends on many-body properties on materials used for building optical devices.

The project aims to develop a distinct family of optoelectronic devices by exploiting many-body interactions in semiconducting bilayers. Recent results show a highly nonlinear polaritonic response in systems of transition metal dichalcogenides (TMDCs) when these 2D materials are doped with excessive charge (for instance, free electrons). In bilayer geometry, they reveal a zoo of various intralayer and interlayer quasiparticles based on bound electron-hole pairs correlated with electrons. By coupling these quasiparticles to light, we expect that strong coupling merged with many-body interactions will lead to game-changing increase of polaritonic nonlinearity. However, accessing this physics requires developing new theoretical tools that can capture strong correlations in such a system. Many other properties needed for building polaritonic circuits and processing units are yet to be explored.

In the project, we aim to develop a theoretical description of 2D polaritons in transition metal dichalcogenides and propose blueprints for optoelectronic devices that use polaritonic many-body interactions. Our project is structured around three objectives.
1. We will develop a theoretical description of nonlinear response in doped TMDC bilayers in order to characterise many-body interactions of 2D polaritons.
2. We will study nontrivial transport properties of doped TMDC bilayers to design polaritonic circuits based on many-body interactions.
3. We will use highly nonlinear polaritonic lattices in TMDC heterobilayers to develop polaritonic computational networks.
As a result, we will develop the background for future 2D polaritonic devices based on highly nonlinear bilayer systems.
 
Description First, motivated by developing optoelectronic devices based on optical nonlinearity, we have developed a theory of nonlinear phase space filling for 2D polaritons with arbitrary strength of excitation (paper is now accepted by Physical Review Research). This has supported the understanding of homobilayers we proposed for the collaborative work (Sheffield; Nat. Comm.) and recent study of fast optoelectronic switches developed by Cerullo lab (Milano, to be submitted). Another collaborative work with Germany and Singapore builds on our theory now in the pulsed regime, where we simulated nonlinear dynamical effects. Second, bypassing the limitations from materials with exchange-dominated interactions, we have developed understanding on nonlinear properties for materials with strong Rydberg-induced interactions and light-matter coupling in those systems. This has also been confirmed in the recent major work with Dortmund, Sheffield, and St Andrews. With the theoretical studies of the bilayers and trilayers are now being partially complete (and results being summarized for publication), we proceed to developing compute capabilities based on polaritonic systems.
Exploitation Route The theory of nonlinear phase space filling represents a versatile tool for describing modern experiments, and we have shared this with the community (e.g. extensively discussed during EPIC23 and CRISTMAS23). The developed mathematical framework has formed the basis for dynamical effects and thus -- development of optoelectronic devices.
Sectors Digital/Communication/Information Technologies (including Software)

Electronics
 
Description One impact of the given proposal concerns development of policies and shaping the future of developing optical and quantum devices in the UK. This was achieved through participating in the panel discussions (Torbay Hi-Tech Cluster in photonics) and participation in the prioritisation panel. Second, the development of background polaritonic devices has urged me to participate in several events related to sensing (as a promising avenue for applications of 2D polaritons) and, specifically, sensing for the defence sector (FS &PNT, Nottingham 2023). While the impact is yet to be estimated, it is an important motivation for the future research.
First Year Of Impact 2023
Sector Aerospace, Defence and Marine,Communities and Social Services/Policy,Electronics
Impact Types Policy & public services
 
Description Serving as a panel member for prioritisation of fellowships and new investigator awards
Geographic Reach National 
Policy Influence Type Participation in a guidance/advisory committee
 
Description Standard Grant call by EPSRC (consortium)
Amount £1,079,471 (GBP)
Funding ID EP/Y021339/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 03/2024 
End 02/2027
 
Title Data for Nonlinear Rydberg exciton-polaritons in Cu2O microcavities 
Description Experimental data for the Light: Science & Applications article "Nonlinear Rydberg exciton-polaritons in Cu2O microcavities" 
Type Of Material Database/Collection of data 
Year Produced 2024 
Provided To Others? Yes  
Impact We have helped preparing and analysing the experimental dataset for nonlinear properties of polaritons in Cu2O. 
URL https://orda.shef.ac.uk/articles/dataset/Data_for_Nonlinear_Rydberg_exciton-polaritons_in_Cu2O_micro...
 
Title Data for Nonlinear Rydberg exciton-polaritons in Cu2O microcavities 
Description Experimental data for the Light: Science & Applications article "Nonlinear Rydberg exciton-polaritons in Cu2O microcavities" 
Type Of Material Database/Collection of data 
Year Produced 2024 
Provided To Others? Yes  
Impact We have compiled a dataset for nonlinear properties of polaritons in Cu2O and corresponding theoretical model for nonlinearity (n2 coefficient). 
URL https://orda.shef.ac.uk/articles/dataset/Data_for_Nonlinear_Rydberg_exciton-polaritons_in_Cu2O_micro...
 
Description Collaboration with Cerullo group at Politecnico di Milano, Italy 
Organisation Polytechnic University of Milan
Country Italy 
Sector Academic/University 
PI Contribution I have teamed up with the group of Prof Giulio Cerullo working on 2D materials and pump-probe spectroscopy. Specifically, I have developed a theory to describe fast switching in bilayer systems that are required for optoelectronic devices and neuromorphic computing.
Collaborator Contribution The group of Prof Cerullo has hosted me during the visit (while giving a talk at Polimi). We have discussed the combination of their experiment and our theory, and have now established excellent working relations.
Impact We have published one Nature Comm. paper together and have completed another joint work on 2D optoelectronic devices to be submitted to Nature Photonics.
Start Year 2023
 
Description Collaboration with Schneider group at the University of Oldenburg 
Organisation Carl von Ossietzky University of Oldenburg
Country Germany 
Sector Academic/University 
PI Contribution We have developed time-dependent theory of saturation for this collaborations, and now discussing various project for 2D materials.
Collaborator Contribution The partners have contributed experimental results and expertise to the joint collaboration, and crucial insights into building the theory.
Impact One of the outputs is the invitation to Oldenburg for giving a talk and extending research, and the paper to be submitted soon.
Start Year 2023
 
Description Collaboration with Tartakovskii group at the University of Sheffield 
Organisation University of Sheffield
Department Sheffield Biorepository
Country United Kingdom 
Sector Academic/University 
PI Contribution I have started to collaborate with Sheffield teams before coming to the UK, but thanks to the New Horizons grant we have shaped it into much wider effort. Spefically, in this case we have developed a theory for nonlinear processes in homobilayers of MoSe2 and Rydberg excitons in Cu2O. Team and myself have managed to explain experimental results for nonlinear process that underpin the future optoelectronic and quantum devices based on this platform.
Collaborator Contribution The group of Prof Tartakovskii has performed experiments guided by our theory, and confirmed fast and strong nonlinear processes based on phase space filling. We have regular in-person meetings on average twice a year, and regular videocalls to continue the collaboration,
Impact The collaboration resulted into 2 major works (Nature Comm. and Light: Sci. & Appl.), with one more Nature-portfolio submission to be out soon. It has led to the public event on quantum tech commercialisation (Oct 2023), and numerous scientific talks.
Start Year 2021
 
Description Partnership with Krizhanovskii group at the University of Sheffield 
Organisation University of Sheffield
Country United Kingdom 
Sector Academic/University 
PI Contribution To date, the contributions from Exeter has provided theoretical explanations of nontrivial quantum and nonlinear effects in polaritonic systems. We started to develop a collaboration with the group of Prof. D. N. Krizhanovskii in 2019, with the first project being the theoretical explanation of nonlinear saturation of trion polaritons in monolayers. Seeing tremendous promise in this area (part of the WP1 of the project), we have described theoretically quantum effects in TMD polaritonic system (published in Phys. Rev. Lett. prior to NIA start due to COVID-related delay, see portfolio). The collaboration with the group of Prof. A. Tartakovskii has started in 2021 as a part of NIA project, and has lead to completed experimental and theoretical studies of dipolaritons in TMD bilayers. We have successfully described the experimental findings in homobilayers, and new .
Collaborator Contribution In the first year of NIA the close collaboration with experimental teams in Sheffield has allowed to reach two crucial milestones. First is an observation of the single polariton phase shift, with far reaching implications for polaritonic quantum information processing. Second milestone is observation of TMD dipolaritons with enhanced nonlinear response, which we have modelled with a distinct theoretical model. In the second year of the project we have continued collaboration on the nonlinear polaritonic effects, explaining the Rydberg blockade-induced nonlinearity (theory + experiment). The paper is in the preparation stage and shall be submitted soon. We have also conducted several collaborative visits, in particular staying in Sheffield for discussions with groups of Prof. Krizhanovskii and Tartakovskii.
Impact Current collaboration has led to 3 published papers, including Nature Photonics. Other our papers are regularly presented to experimental colleagues in order to implement them in practice.
Start Year 2021
 
Title Code for Nonlinear Rydberg exciton-polaritons in Cu2O microcavities 
Description code for the Light: Science & Applications article "Nonlinear Rydberg exciton-polaritons in Cu2O microcavities" 
Type Of Technology Software 
Year Produced 2024 
Impact Nonlinear optics requires robust methods for benchmarking the strength of nonlinearity. We have developed a package that can convert interaction constants and specific nonlinear saturation processes into a standard nonlinear refractivity (known as n2 coefficient). 
URL https://orda.shef.ac.uk/articles/software/Code_for_Nonlinear_Rydberg_exciton-polaritons_in_Cu2O_micr...
 
Description Community pulse check @ EPIC2023 
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 During the EPIC 2023 event in Singapore I have run a pulse check for the polaritonic community asking a question: "Where do we go from now in terms of making polaritonic research impactful?" This has triggered a week-long discussions with peers who shared opinions, and converged on the idea that polaritonic computing and quantum polaritonics are the two most-rewarding big goals to be followed. The Polish group of Barbara Pietka has invited me to Warsaw to follow up on the discussions.
Year(s) Of Engagement Activity 2023
 
Description Conference on Research and Innovations in Science and Technology of Materials 2023 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact I have presented our advances and project's work during the CRISTMAS conference in Paris. This has led to follow up discussions with researchers from Trinity College Dublin (invitation to contribute research to the new quantum tech journal) and arranged visit to the University of Bath for the general colloquium.
Year(s) Of Engagement Activity 2023
 
Description Invited talk at EPIC 2023 in Singapore (top year's conference in polaritonics) 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact I have presented our results on the project to the core audience in polaritonics that included major groups active in the field. The dissemination led to 1 paper we are finishing with Germany/Singapore consortium, invitation to Poland (Warsaw) and Germany (Oldenburg) for discussing polaritonic computing, and joint project with another German group (Wuerzburg) on bilayers.
Year(s) Of Engagement Activity 2023
 
Description Participating at Commercializing Quantum 2023 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact I have participated in the second edition Commercializing Quantum by The Economist, engaging in the discussions with businesses, investors, and researchers in the area. This has helped to promote the importance of optical computing as a part of the wider strategy to sustainable AI and generated follow ups.
Year(s) Of Engagement Activity 2023
 
Description Participating at the Future Sensing and PNT symposium 2023 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact I have conducted the use-case search and discussions for polaritonic and QML defence applications. Discussed with top defence sector representatives and supplies the challenges. Contributed to discussion groups on quantum tech, and followed up with plans for potential spinning out.
Year(s) Of Engagement Activity 2023
 
Description Participation in the UK National Quantum Technologies Showcase 2023 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact I have joined the NQTS 2023, engaging with the discussions on promising applications of theory and algorithms that we develop. Specifically, I have conducted the survey for applications (market research) in quantum and optical sensing, connecting with a wide range of hardware, midstack, and software providers in the quantum area.
Year(s) Of Engagement Activity 2023
 
Description Presentating the vision of polaritonic computing at the Torbay HiTech Cluster event 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Industry/Business
Results and Impact The event has combined photonics industry representatives active in the regional hub, and the students from Torbay area looking forward to join the sector. The specific area of photonic computing and its quantum applications has sparked the interest to the subject. This has ultimately led to including the very same subject as a priority for the department in Exeter.
Year(s) Of Engagement Activity 2023
 
Description Reviewing the state-of-the-art in nonlinear polaritonics in the talk at Politecnico di Milano 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact I have presented our research, conducted the lab tours, and brainstormed new ideas with peers at Polimi. We have started the collaboration that now results into new optoelectronic devices based on the theory developed in the project.
Year(s) Of Engagement Activity 2023
 
Description TED talk "Living both worlds: academia and industry" delivered to a broad audience at the University of Sheffield 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Postgraduate students
Results and Impact I have discussed and shared good practices of interacting with businesses as an academic who regularly works on indeustrially-led projects. This has covered both research in quantum computing and quantum optics. The event has sparked the discussion among PhD graduates on ways to contribute to the future of quantum industry, and converted in 10+ LinkedIn connection and private messages asking for the advice.
Year(s) Of Engagement Activity 2023