Monday, 18 August 2025 4:00pm – 5:00pm

This seminar will be delivered in Lecture Theatre 4

Speaker: Adesh Kushwaha

Host: Prof. Ivan Kassal

Title: Demonstrating Quantum-Enhanced Light Harvesting

Abstract
Quantum effects can enhance light-harvesting efficiency. In particular, supertransfer—a collective enhancement of energy transport via delocalised excitations—has been proposed to play a role in photosynthesis, yet has never been directly observed because natural molecular systems do not allow delocalisation to be switched on and off. We show how a programmable superconducting device can overcome this barrier, enabling tunable delocalisation and the first direct observation of supertransfer.

In parallel, we establish rigorous limits on enhancing light-harvesting efficiency using optical coherence. In the weak-light, long-timescale, and orientationally disordered regime relevant to most molecular systems, optical coherences cannot improve efficiency once averaged over realistic time scales.

Extending beyond light-harvesting, we unify a broad class of collective effects in emission, transfer, and absorption that have been proposed for energy storage and quantum batteries. We unify these diverse collective effects and introduce new ones, providing guidelines to make them robust. Our guidelines for engineering supertransfer and collective effects in general could inform the design of future quantum-enhanced light harvesters.