Periodic Reporting for period 4 - QTONE (Quantum Plasmomechanics with THz Phonons and Molecular Nano-junctions)
Reporting period: 2024-02-01 to 2024-11-30
This project addresses the issue of whether vibrational modes of molecules and 2D materials can be probed in the quantum regime and/or driven into the nonlinear regime under optical excitation. The tools being used include ultrashort laser pulses, single-photon detectors, and plasmonic nanocavities.
The importance for society lies in the development of nanoscale devices for nonlinear optics, the discovery of new tools for single-molecule sensing, and the control of chemical reactions and other molecular processes using light.
The overall objectives are to improve our understanding of light-matter interaction inside plasmonic nanocavities, in particular how molecular vibrations react to optical driving in a plasmonic cavity.
The importance for society lies in the development of nanoscale devices for nonlinear optics, the discovery of new tools for single-molecule sensing, and the control of chemical reactions and other molecular processes using light.
The overall objectives are to improve our understanding of light-matter interaction inside plasmonic nanocavities, in particular how molecular vibrations react to optical driving in a plasmonic cavity.
This ERC Consolidator Grant focused on advancing the fields of nano-plasmonics, quantum optics, and molecular vibrations through three major sub-projects. Below is a summary of the work performed and the main results achieved, including their broader implications and dissemination efforts.
Research Achievements
1. Sub-project TecQ - Terahertz cavity Quantum Optomechanics
• We successfully generated two-mode entangled states in molecular vibrations, observing quantum beats in liquid carbon disulfide, a hallmark of collective quantum coherence at room temperature ([Nature Comm. 2023]).
• Demonstrated a heralded single quantum of vibration (phonon) in bulk diamond at room temperature, enabling tunable sources of pure single photons ([Phys. Rev. X 2019]).
• Established Bell correlations between light and vibrations under ambient conditions, highlighting novel room-temperature quantum phenomena ([Science Adv. 2020]).
• Collaborated internationally to measure and characterize polarization entanglement in joint photon-phonon states in diamond ([Phys. Rev. A 2023, under review at Phys. Rev. Lett., arXiv:2408.11477]).
2. Sub-project DyBa - Dynamical Backaction at the Molecular Scale
• Developed new nanocavity designs and explored molecular optomechanical phenomena, leading to breakthroughs in plasmonic cavity coupling and nonlinear spectroscopic techniques.
• Achieved coherent mid-infrared upconversion under continuous-wave laser excitation using dual-resonant plasmonic cavities ([Science 2021]).
• Pioneered exciton-assisted molecular optomechanics by coupling single dye molecules with plasmonic nanodimers, reaching a regime of strong interactions among excitons, vibrations, and cavities ([ACS Nano 2025]).
3. Sub-project SMol - Single Molecule Electro-Optomechanics
• Combined lithography and self-assembly to fabricate static molecular junctions, revealing single-molecule conduction events under plasmonic enhancement ([ACS Photonics 2024]).
• Advanced toward deterministic transport and optical measurements at the single-molecule level, with ongoing efforts supported by subsequent funding.
Methodological and Interdisciplinary Innovations
• Developed a self-stabilized time-bin interferometer for hybrid photon-phonon state analysis.
• Introduced a novel approach combining fiber spectroscopy and Bell inequality measurements for polarization entanglement characterization over a broad frequency range.
• Translated expertise in surface-enhanced Raman spectroscopy (SERS) into applied projects in food safety and oncology, in collaboration with industrial and medical partners.
Dissemination and Exploitation
• Results have been disseminated through high-impact journal publications, international conferences, and collaborative projects.
• Technological advancements are being using for new applications in spectroscopy and biomedical diagnostics.
Research Achievements
1. Sub-project TecQ - Terahertz cavity Quantum Optomechanics
• We successfully generated two-mode entangled states in molecular vibrations, observing quantum beats in liquid carbon disulfide, a hallmark of collective quantum coherence at room temperature ([Nature Comm. 2023]).
• Demonstrated a heralded single quantum of vibration (phonon) in bulk diamond at room temperature, enabling tunable sources of pure single photons ([Phys. Rev. X 2019]).
• Established Bell correlations between light and vibrations under ambient conditions, highlighting novel room-temperature quantum phenomena ([Science Adv. 2020]).
• Collaborated internationally to measure and characterize polarization entanglement in joint photon-phonon states in diamond ([Phys. Rev. A 2023, under review at Phys. Rev. Lett., arXiv:2408.11477]).
2. Sub-project DyBa - Dynamical Backaction at the Molecular Scale
• Developed new nanocavity designs and explored molecular optomechanical phenomena, leading to breakthroughs in plasmonic cavity coupling and nonlinear spectroscopic techniques.
• Achieved coherent mid-infrared upconversion under continuous-wave laser excitation using dual-resonant plasmonic cavities ([Science 2021]).
• Pioneered exciton-assisted molecular optomechanics by coupling single dye molecules with plasmonic nanodimers, reaching a regime of strong interactions among excitons, vibrations, and cavities ([ACS Nano 2025]).
3. Sub-project SMol - Single Molecule Electro-Optomechanics
• Combined lithography and self-assembly to fabricate static molecular junctions, revealing single-molecule conduction events under plasmonic enhancement ([ACS Photonics 2024]).
• Advanced toward deterministic transport and optical measurements at the single-molecule level, with ongoing efforts supported by subsequent funding.
Methodological and Interdisciplinary Innovations
• Developed a self-stabilized time-bin interferometer for hybrid photon-phonon state analysis.
• Introduced a novel approach combining fiber spectroscopy and Bell inequality measurements for polarization entanglement characterization over a broad frequency range.
• Translated expertise in surface-enhanced Raman spectroscopy (SERS) into applied projects in food safety and oncology, in collaboration with industrial and medical partners.
Dissemination and Exploitation
• Results have been disseminated through high-impact journal publications, international conferences, and collaborative projects.
• Technological advancements are being using for new applications in spectroscopy and biomedical diagnostics.
Key Achievements
1. Optomechanical Bell correlations at ambient conditions ([Science Adv. 2020]).
2. Quantum coherence in molecular vibrations under spontaneous Raman scattering ([Nature Comm. 2023]).
3. Molecular cavity optomechanics enabling vibrational sum-frequency generation with ultra-low continuous-wave laser powers ([Science 2021]).
4. Purcell effect and Lamb shift in DNA-assembled nanocavities with single molecules ([ACS Nano 2025]).
5. Fluctuations in light emission and conductance in molecular junctions ([ACS Photonics 2024]).
Breakthroughs and Impact
• The achievement in vibrational sum-frequency generation represents a significant advancement, enabling single-molecule sensitivity and the use of continuous-wave lasers, previously unattainable with conventional techniques.
• Demonstrations of quantum coherence and Bell correlations in room-temperature systems provide intuitive insights into quantum mechanics and broaden its practical applicability.
• Interdisciplinary collaborations have resulted in technology transfer to applied sectors, expanding the impact of fundamental research.
1. Optomechanical Bell correlations at ambient conditions ([Science Adv. 2020]).
2. Quantum coherence in molecular vibrations under spontaneous Raman scattering ([Nature Comm. 2023]).
3. Molecular cavity optomechanics enabling vibrational sum-frequency generation with ultra-low continuous-wave laser powers ([Science 2021]).
4. Purcell effect and Lamb shift in DNA-assembled nanocavities with single molecules ([ACS Nano 2025]).
5. Fluctuations in light emission and conductance in molecular junctions ([ACS Photonics 2024]).
Breakthroughs and Impact
• The achievement in vibrational sum-frequency generation represents a significant advancement, enabling single-molecule sensitivity and the use of continuous-wave lasers, previously unattainable with conventional techniques.
• Demonstrations of quantum coherence and Bell correlations in room-temperature systems provide intuitive insights into quantum mechanics and broaden its practical applicability.
• Interdisciplinary collaborations have resulted in technology transfer to applied sectors, expanding the impact of fundamental research.