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Updated: Mar 7, 2026
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Light-Activated Qubit Coupling in a Vanadyl Porphyrin Trimer
Alberto Privitera1,2, Alessandro Chiesa3, Fabio Santanni4,5
1Department of Industrial Engineering, University of Florence & UdR INSTM Firenze, Firenze 50121, Italy.
Journal of the American Chemical Society
|March 6, 2026
Summary
Researchers developed a molecular system for quantum information science. Photoexcitation triggers ultrafast interactions between molecular qubits, enabling light-activated quantum gates at room temperature.
Area of Science:
- Quantum information science
- Molecular quantum computing
- Spin dynamics in molecules
Background:
- Molecules offer a tunable platform for quantum information science.
- Advances in optical spin initialization, control, and readout of molecular qubits have been achieved.
- A key challenge is creating scalable architectures via controlled interqubit interactions.
Purpose of the Study:
- To present a molecular system for optically controlled interqubit interactions.
- To demonstrate ultrafast coupling of magnetically independent molecular qubits upon photoexcitation.
- To provide a proof of concept for light-activated molecular quantum gates.
Main Methods:
- Utilized a molecular system of two vanadyl porphyrin qubits bridged by a free-base porphyrin.
- Employed femtosecond transient absorption and time-resolved electron paramagnetic resonance (TREPR) spectroscopy.
- Performed DFT calculations and spectral simulations for theoretical support.
Main Results:
- Photoexcitation induced coupling between qubits via a spin-quintet state formation within subpicosecond timescales.
- Observed long-lived spin polarization persisting up to room temperature.
- Demonstrated optically controlled spin interactions in molecules.
Conclusions:
- The presented molecular system enables ultrafast, light-activated interqubit interactions.
- This mechanism is a crucial step towards scalable molecular quantum computing architectures.
- The findings pave the way for developing novel light-activated molecular quantum gates.
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