Creating optically and electrically addressable spin-photon interfaces for scalable quantum networks
Transition metal dichalcogenides (TMDCs) possess valley pseudospin, allowing photon spin to be coupled to electron spin and enabling initialization and readout of both classical and quantum information. Rapid valley-dephasing processes have impeded the development of scalable, high-performance valleytronic devices operating at room temperature. We employ high-Q-factor resonant chiral metasurfaces to enhance exciton transitions and enable room-temperature valley-selective emission, which could facilitate the development of compact chiral classical and quantum light sources and the creation of molecular chiral polaritons for quantum enantioselective synthesis.
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Nat. Commun., 2025. link.
Nanophotonics, 2025. link.
Nanophotonics, 2023. link.
Interrogating quantum emitters in van der Waals materials using single-photon spectroscopy
The development of many quantum optical technologies depends on the availability of single quantum emitters with near-perfect coherence. However, systematic improvement is limited by a lack of understanding of the microscopic energy flow at the single-emitter level and ultrafast timescales. We utilize a combination of fluorescence correlation spectroscopy with ultrafast spectroscopy to capture the sample-averaged dynamics of defects with single-particle sensitivity in h-BN nanoflakes. From milliseconds to nanoseconds, the translational, shelving, rotational and antibunching features are disentangled in time, which quantifies the normalized two-photon emission quantum yield. Leveraging the femtosecond resolution of this technique, we visualize electron–phonon coupling and discover the acceleration of polaronic formation on multi-electron excitation. Our work provides a framework for ultrafast spectroscopy in heterogeneous emitters, opening new avenues of extreme-scale characterization for quantum applications.
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Nat. Mater., 2024. link.
Measuring and controlling plasmonic-photonic hybrid systems
To exert control over the interaction between photons and plasmons, it is essential to identify the underlying energy pathways which influence the system’s dynamics and determine the critical system parameters, such as the coupling strength and dissipation rates. We simultaneously measure both photothermal absorption and two-sided optical transmission in a coupled plasmonic–photonic cavity consisting of plasmonic gold nanorods deposited on a toroidal whispering-gallery-mode optical microresonator. We determine all system parameters with a dynamic range spanning 9 orders of magnitude.
Active control of couplings in a hybrid plasmonic-photonic cavity is challenging but rewarding to tailor light-matter interactions for photonic applications and quantum information science. We demonstrate this control in a model system where plasmonic nanoparticles interact with a microbubble microcavity and present a new approach to actively modulate plasmonic-photonic interaction.
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Nano Lett., 2020. link.
J. Phys. Chem. C, 2022. link.
Annu. Rev. Phys. Chem., 2024. link.
Single-particle photothermal absorption imaging and spectroscopy
Whispering-gallery mode (WGM) microresonators have recently been employed as platforms for label-free single-molecule and single-particle detection, imaging, and spectroscopy. We fabricate all-glass toroidal microresonators on a coverslip thickness (~170 μm) substrate, enabling excitation delivery through the sample, simplifying optical integration. Further, we demonstrate the application of this new geometry for single-particle photothermal imaging.
We use optical WGM-based absorption spectrometers to perform single-particle measurements on conjugated polymers (e.g. PEDOT:PSS) used as hole transport layers in photovoltaics, providing a bottom-up examination of electronic structure and morphology ranging from single polymers to nascent films. Using single-particle spectroscopy with complementary theoretical calculations and ultrafast spectroscopy, we demonstrate that PEDOT:PSS displays bulk-like optical response even in single polymers. We also investigate the effects of thermal annealing and dimethyl sulfoxide (DMSO) post-treatment on PEDOT:PSS, from the nano- to mesoscale.
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Opt. Expr., 2018. link.
Nano Lett., 2018. link
J. Phys. Chem. C, 2019. link
