Optical Characterization of a Single Quantum Emitter Based on Vanadium Phthalocyanine Molecules

TL;DR

This study demonstrates the optical stability and characterization of individual vanadium-oxide phthalocyanine molecules at room temperature, highlighting their potential as stable quantum emitters for quantum technologies.

Contribution

First report of optical properties of single VOPc molecules, supported by theoretical analysis, advancing their application in quantum information processing.

Findings

Single VOPc molecules exhibit stable optical emission at room temperature.

Optical response aligns with pyramidal C₄v symmetry model.

Non-radiative transition rates depend on excitation wavelength.

Abstract

Single quantum emitters play a fundamental role in the development of quantum technologies such as quantum repeaters, and quantum information processing. Isolating individual molecules with stable optical emission is an essential step for these applications, specially for those molecules that present large coherence times at room temperature. Among them, vanadium-oxide phthalocyanine (VOPc) molecules stand out as promising candidates due to their large coherence times measured in ensemble. However, the optical properties of individual molecules have not yet been reported. Here we show that single VOPc molecules with stable optical properties at room temperature can be isolated. We find that the optical response of the molecule under laser illumination of different polarization agrees well with a system having pyramidal C$_{4v}$ symmetry. Furthermore, the molecule reveals a non-radiative transition rate that depends on the excitation wavelength when its lifetime is interrogated. We provide theoretical calculations that support our experimental findings and provide insight to the role of phonons and internal electronic structure of the molecule. These results demonstrate that this single paramagnetic molecule can function as a single quantum emitter while displaying optical stability under ambient conditions to have their intrinsic properties investigated.