In recent decades, significant progress has been made in constructing and studying individual quantum systems based on two level atoms (molecules) and photons. Here we demonstrate that the quadruply bonded Mo2 unit, with a MoMo bond distance as short as 2.1A, functions as an innate emitter resonator molecular quantum system capable of trapping visible light photons between the two molybdenum atoms under ambient conditions, thereby generating an intense quantized local electromagnetic field with an extremely small mode volume. The resonance fluorescence spectra of three Mo2 complexes indicate that the intermetallic Mo-Mo charge transfer transition is coherently coupled to the local scattering field, exhibiting vacuum Rabi splitting and Mollow triplets. Resonant coupling of single molecules and N-molecule ensembles to the scattered light through sideband excitation produces a sequence of discrete optical modes spanning a broad wavelength range, with polaritonic transitions identical to those observed in Ni2 based systems. These results establish the Mo2 molecule as an independent emitter resonator integrated quantum system that enables quantum optical experiments in free space using conventional spectroscopic instrumentation. This work extends quantum electrodynamics into molecular science, providing new insights into metal metal bonding, molecular physics, and light matter interactions.
In recent decades, significant progress has been made in constructing and studying individual quantum systems based on two level atoms (molecules) and photons. Here we demonstrate that the quadruply bonded Mo2 unit, with a MoMo bond distance as short as 2.1A, functions as an innate emitter resonator molecular quantum system capable of trapping visible light photons between the two molybdenum atoms under ambient conditions, thereby generating an intense quantized local electromagnetic field with an extremely small mode volume. The resonance fluorescence spectra of three Mo2 complexes indicate that the intermetallic Mo-Mo charge transfer transition is coherently coupled to the local scattering field, exhibiting vacuum Rabi splitting and Mollow triplets. Resonant coupling of single molecules and N-molecule ensembles to the scattered light through sideband excitation produces a sequence of discrete optical modes spanning a broad wavelength range, with polaritonic transitions identical to those observed in Ni2 based systems. These results establish the Mo2 molecule as an independent emitter resonator integrated quantum system that enables quantum optical experiments in free space using conventional spectroscopic instrumentation. This work extends quantum electrodynamics into molecular science, providing new insights into metal metal bonding, molecular physics, and light matter interactions.
ABSTRACT In recent decades, significant progress has been made in constructing and studying individual quantum systems based on two‐level atoms (molecules) and photons. Here we demonstrate that the quadruply bonded Mo 2 unit, with a Mo─Mo bond distance as short as 2.1 Å, functions as an innate emitter–resonator molecular quantum system capable of trapping visible‐light photons between the two molybdenum atoms under ambient conditions, thereby generating an intense quantized local electromagnetic field with an extremely small mode volume. The resonance fluorescence spectra of three Mo 2 complexes indicate that the intermetallic Mo→Mo charge‐transfer transition is coherently coupled to the local scattering field, exhibiting vacuum Rabi splitting and Mollow triplets. Resonant coupling of single molecules and N ‐molecule ensembles to the scattered light through sideband excitation produces a sequence of discrete optical modes spanning a broad wavelength range, with polaritonic transitions identical to those observed in Ni 2 ‐based systems. These results establish the Mo 2 molecule as an independent emitter–resonator integrated quantum system that enables quantum‐optical experiments in free space using conventional spectroscopic instrumentation. This work extends quantum electrodynamics into molecular science, providing new insights into metal–metal bonding, molecular physics, and light–matter interactions.
Quadruply Bonded Mo2 Molecules Acting as an Inborn Emitter-Resonator Quantum System in Free Space
In recent decades, significant progress has been made in construction and study of individual quantum systems consisting of the basic single matter and energy particles, i.e., atoms and photons, which show great potentials in quantum computation and communication. Here, we demonstrate that the quadruply-bonded Mo2 unit of the complex can trap photons of visible light under ambient conditions, producing intense local electromagnetic (EM) field that features squeezed states, photon antibunching, and vacuum Rabi splitting. Our results show that both the electronic and vibrational states of the Mo2 molecule are modified by coherent coupling with the scattered photons of the Mo2 unit, as evidenced by the Rabi doublet4 and the Mollow triplet in the incoherent resonance fluorescence and the Raman spectra. The Mo2 molecule, acting as an independent emitter-resonator integrated quantum system, allows optical experiments to be conducted in free space, enabling fundamental quantum phenomena to be observed through conventional spectroscopic instrumentation. This provides a new platform for study of field effects and quantum electrodynamics (QED) in the optical domain. The insights gained from this study advance our understanding in metal-metal bond chemistry, molecular physics and quantum optics, with applications in quantum information processing, optoelectronic devices and control of chemical reactivity.
Confining optical fields to molecular dimensions is a central objective in nanophotonics and molecular quantum optics. Here, we report strong coupling of the Mo Mo stretching vibration to a locally confined Raman scattering field in quadruply bonded dimolybdenum complexes. Under ambient, cavity-free conditions, the dimolybdenum formamidinate complexes Mo2(DAniF)4 and Mo2(DTolF)4 exhibit Rabi-type splitting, Mollow-type sidebands, and higher-order Raman features centered near the Mo Mo stretching frequency of 400 cm-1, indicating formation of dressed vibration field states. The sideband displacements from the resonance follow the photon-number-dependent relation Ωn=Ωνn, consistent with Jaynes Cummings-type coupling, while strongly displaced Raman features are assigned to leapfrog transitions within the same dressed-state ladder. In contrast, the less polarizable Mo2(O2CCH3)4 complex exhibits essentially a single Mo Mo stretching band. Reanalysis of reported resonance Raman spectra of an alkynyl Mo2 complex further supports this coupling framework. These results suggest that the Mo2 unit simultaneously serves as the Raman active oscillator and the molecular resonator that supports, confines, and enhances the locally generated scattering field, providing spectroscopic evidence for vibration field coupling and optical-field confinement within a chemically defined metal metal bond.
Quantization of Visible Light by a Ni2 Molecular Optical Resonator
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 (Ni2) 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 Ni2 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 Ni2 as a robust platform for quantum optical phenomena under ambient conditions, offering new pathways for molecular physics, polaritonic chemistry and quantum information processing.
Field quantization is fundamental to quantum optics and polaritonic chemistry, enabling exploration of light–matter interactions at the quantum level. We report resonant coupling between the two-level excitation of a dinickel (Ni₂) complex and its locally recycled scattering field under ambient, cavity-free conditions. This Ni₂ system exhibits hallmark resonance-fluorescence features, including Rabi doublets and Mollow triplets, with strong coupling achieved under weak, non-resonant excitation. The Ni₂ unit functions as a diatomic resonator, enhancing photon scattering and forming a Jaynes–Cummings molecule. Simulations of second-order correlation functions confirm photon antibunching and underdamped Rabi oscillations. Collective coupling strength scales linearly with the number of molecules (N), surpassing Tavis–Cummings model predictions and reaching the ultrastrong coupling regime. These findings establish Ni₂ complexes as robust molecular quantum systems, offering a chemically tunable platform for quantum information processing and coherent chemical control at the molecular scale.
Field quantization is fundamental to quantum optics and polaritonic chemistry, enabling exploration of light–matter interactions at the quantum level. We report resonant coupling between the two-level excitation of a dinickel (Ni₂) complex and its locally recycled scattering field under ambient, cavity-free conditions. This Ni₂ system exhibits hallmark resonance-fluorescence features, including Rabi doublets and Mollow triplets, with strong coupling achieved under weak, non-resonant excitation. The Ni₂ unit functions as a diatomic resonator, enhancing photon scattering and forming a Jaynes–Cummings molecule. Simulations of second-order correlation functions confirm photon antibunching and underdamped Rabi oscillations. Collective coupling strength scales linearly with the number of molecules (N), surpassing Tavis–Cummings model predictions and reaching the ultrastrong coupling regime. These findings establish Ni₂ complexes as robust molecular quantum systems, offering a chemically tunable platform for quantum information processing and coherent chemical control at the molecular scale.