Quantum Plasmonics in Nanostructured Hybrid Systems

Quantum plasmonics investigates the interplay between collective electron oscillations in metallic nanostructures and quantum emitters or confined excitations at the nanoscale. In hybrid systems, metallic nanoparticles, nanowires or thin films are integrated with semiconductor quantum dots, molecular excitons or two-dimensional materials to achieve strong light–matter coupling beyond the classical regime. As the characteristic dimensions of metal–dielectric interfaces approach subnanometre scales, nonlocal screening, electron tunnelling and surface spill-out phenomena significantly alter the optical response, producing resonance blueshifts, enhanced damping channels and hybrid mode splitting. Atomistic frameworks such as time-dependent density functional theory and quantum-corrected hydrodynamic models capture these effects, revealing ultrafast Rabi oscillations, giant nonlinearities and tailored energy transfer in deeply confined hotspots. These hybrid platforms underpin developments in single-photon sources, nanoscale sensors, optical switches and quantum transduction devices. By bridging classical nanophotonics and quantum science, quantum plasmonics in nanostructured hybrids paves the way for on-chip quantum information processing and compact quantum-enabled photonic technologies.

Research from Nature Portfolio

Recent work has shown that quantum mechanical effects dominate plasmonic behaviour when nanogap distances fall below one nanometre. Experimental measurements of subnanometre junctions reveal that electron tunnelling and nonlocal screening introduce additional loss channels and modify near-field enhancements, challenging purely classical descriptions. These insights have been encapsulated in self-consistent hydrodynamic models that account for electron spill-out and density gradients, enabling accurate simulation of size-dependent resonance shifts in nanoparticles and nanowires.

Concurrently, unified treatments of plasmon–emitter interactions employing mesoscopic surface parameters have been developed. By extending electrodynamics with Feibelman d-parameters, researchers have quantified nonclassical resonance shifts and surface-enabled Landau damping, providing a comprehensive framework to predict dipolar and multipolar emission enhancement, plasmon-assisted energy transfer rates and two-photon transition amplitudes in hybrid exciton–plasmon systems.

Quantum Plasmonics in Nanostructured Hybrid Systems publication trend

The graph below shows the total number of articles in quantum plasmonics in nanostructured hybrid systems across all publications each year (not limited to Nature Index journals).

Technical terms

Surface plasmon resonance: Collective oscillation of conduction electrons at a metal–dielectric boundary, producing strong local field enhancement.

Nonlocal response: Optical behaviour in which the dielectric function depends on both frequency and wavevector, reflecting spatial dispersion in the electron gas.

Quantum tunnelling: Electron transmission across potential barriers at distances comparable to its de Broglie wavelength, allowing current flow through subnanometre gaps.

Feibelman parameters: Surface response functions that characterise nonclassical polarisation and electron spill-out at metal interfaces.

Rabi frequency: Rate of coherent energy exchange between a quantum emitter and an optical mode under strong coupling.

Hybrid system: Nanoscale assembly combining plasmonic metals and quantum emitters or excitonic materials to achieve mixed light–matter states.

Quantum size effect: Modification of electronic and optical properties due to quantisation of energy levels in nanoscale structures.

References

1. Quantum mechanical effects in plasmonic structures with subnanometre gaps. Nature Communications (2016).
2. Resonance shifts and spill-out effects in self-consistent hydrodynamic nanoplasmonics. Nature Communications (2015).
3. Plasmon–emitter interactions at the nanoscale. Nature Communications (2020).
4. Coulomb effect in hybrid double quantum dot-metal nanoparticle systems considering the wetting layer. EPJ Quantum Technology (2024).
5. Dispersive surface-response formalism to address nonlocality in extreme plasmonic field confinement. Nanophotonics (2023).
6. Mesoscopic electrodynamics at metal surfaces. Nanophotonics (2021).