Institut des
NanoSciences de Paris

Théorie de la décohérence quantique, effet de l’environnement

(A. Chin)

Every quantum technology (QT) attempts to exploit the non-classical properties of light and matter to achieve supremacy and potentially exponentially enhanced efficiencies over classical, deterministic approaches to tasks such as computation, communications, sensing and metrology [1]. However, highly entangled quantum states - and especially many-body ones – are prone to deleterious effects arising from the ubiquitous action of uncontrollable interactions between the quantum systems and the unobservable and constantly fluctuating degrees of freedom in its environment. This leads to rapid and irreversible processes such as decoherence and thermalisation that destroy quantum technological resources, such as multi-partite entanglement, and presently limit the development of any scalable QTs. My work explores the microscopic, real-time and non-equilibrium physics of decoherence, and the rich theoretical phenomenology of “open quantum systems”. By modelling, simulating and analysing the fundamental interactions of quantum systems with large numbers of environmental degrees of freedom, we hope to provide insight into the potential control and suppression of noise and error sources in realistic, solid state platforms for future QTs. On top of this, we also develop powerful theoretical methods to study the dynamics of highly non-perturbative open quantum systems, allowing us to explore the world of biological and organic optoelectronic materials. This work in the field of Tensor Network Dynamics [ 2] has been a decisive contribution to the fascinating and rapidly growing domain of “molecular quantum technologies” where – somewhat surprisingly – an interplay of both dissipative and coherent quantum dynamics could be harnessed in specially designed functional quantum materials for a broad range of organic energy harvesting and catalytic applications [3].

[1] Quantum metrology in non-Markovian environments : AW Chin, SF Huelga, MB Plenio : Physical review letters 109 (23), 233601 (2013) [2] Tensor network simulation of multi-environmental open quantum dynamics via machine learning and entanglement renormalisation : FAYN Schröder, DHP Turban, AJ Musser, NDM Hine, AW Chin : Nature communications 10 (1), 1062 (2019) [3] Ultrafast long-range charge separation in organic semiconductor photovoltaic diodes : S Gélinas, A Rao, A Kumar, SL Smith, AW Chin, et al. : Science 343 (6170), 512-516 (2014).


Image caption : Strongly coupled open quantum systems appear naturally in organic systems, leading to novel quantum dynamics with potential advantages for energy applications. (Left) Nanoscale photosynthetic proteins efficiently transport and focus excitons through coherently delocalised states. (Middle) In singlet fission, a photoexcitation spontaneously generates a pair of spin-entangled excitations that can distribute quantum resources in the solid state [2]. (Right) Non-markovian effects and the ultrafast classical-to quantum transition induced by molecular environments can play a key role in the critical charge separation event in organic photovoltaics [3].

Key Collaborators and Funded Projects :
- Lovett Group, St Andrews (UK) : “Quantum dynamics and control of Bio-Inspired Nanomachines”. Bi-lateral Funding : La direction générale de l’Armement (DGA) and le Defence Science and Technology Laboratory (DSTL).
- Rao Group, University of Cambridge (UK) : Various projects related to the prediction and observation of spatio-temporally resolved open quantum dynamics in organic nanostructures.