Femtosecond Coherence and Quantum Control of Single Molecules at Room Temperature

TL;DR

This paper demonstrates the creation, probing, and control of quantum coherences in single molecules at room temperature using femtosecond pulse shaping, revealing structural heterogeneity and enabling basic quantum operations.

Contribution

It introduces a novel method to manipulate and measure quantum coherences in individual molecules under ambient conditions, advancing quantum control in biological and organic systems.

Findings

Quantum coherences can be created and manipulated in single molecules at room temperature.

Structural heterogeneity affects coherence decay times across molecules.

Rabi oscillations demonstrate control of quantum states in single molecules.

Abstract

Quantum mechanical phenomena, such as electronic coherence and entanglement, play a key role in achieving the unrivalled efficiencies of light-energy conversion in natural photosynthetic light-harvesting complexes, and triggered the growing interest in the possibility of organic quantum computing. Since biological systems are intrinsically heterogeneous, clear relations between structural and quantum-mechanical properties can only be obtained by investigating individual assemblies. However, single-molecule techniques to access ultrafast coherences at physiological conditions were not available so far. Here we show by employing femtosecond pulse-shaping techniques that quantum coherences in single organic molecules can be created, probed, and manipulated at ambient conditions even in highly disordered solid environments. We find broadly distributed coherence decay times for different individual molecules giving direct insight into the structural heterogeneity of the local surroundings. Most importantly, we induce Rabi-oscillations and control the coherent superposition state in a single molecule, thus performing a basic femtosecond single-qubit operation at room temperature.