Quantization of Visible Light by a Ni$_2$ Molecular Optical Resonator

TL;DR

This paper demonstrates that a dinickel complex (Ni₂) can trap and quantize visible light, acting as a quantum system that produces nonclassical light and exhibits ultrastrong coupling, advancing molecular quantum optics.

Contribution

It introduces Ni₂ as a novel molecular platform for quantum optical phenomena, capable of ultrastrong coupling and nonclassical light generation under ambient conditions.

Findings

Achieved vacuum Rabi splitting of 1.2 eV at 3.25 eV resonance.

Observed photon antibunching and squeezed states in the system.

Demonstrated collective coupling scaling linearly with N, enabling ultrastrong coupling.

Abstract

The quantization of an optical field is a frontier in quantum optics with implications for both fundamental science and technological applications. Here, we demonstrate that a dinickel complex (Ni$_2$) traps and quantizes classical visible light, behaving as an individual quantum system or the Jaynes Cummings molecule.The composite system forms through coherently coupling the two level NiNi charge transfer transition with the local scattering field, which produces nonclassical light featuring photon anti bunching and squeezed states, as verified by a sequence of discrete photonic modes in the incoherent resonance fluorescence. Notably, in this Ni$_2$ system, the collective coupling of N molecule ensembles scales as N, distinct from the Tavis-Cummings model, which allows easy achievement of ultrastrong coupling. This is exemplified by a vacuum Rabi splitting of 1.2 eV at the resonance (3.25 eV) and a normalized coupling rate of 0.18 for the N = 4 ensemble. The resulting quantum light of single photonic modes enables driving the molecule field interaction in cavity free solution, which profoundly modifies the electronic states. Our results establish Ni$_2$ as a robust platform for quantum optical phenomena under ambient conditions, offering new pathways for molecular physics, polaritonic chemistry and quantum information processing.