arXiv subjects

Cedric Bray

Publications and source records attributed to Cedric Bray.

3 recordsLinked to original sources

arXiv2026

Terahertz cavity hybridization of collective proteins vibrations

Hybrid light-matter states have transformed photonics, yet their realization with driven collective vibrations in biological systems remains an open challenge. Here we show that optically pumped R-phycoerythrin proteins at room temperature support coherent sub-terahertz vibrational modes consistent with Frohlich condensation, and that these modes hybridize with confined terahertz cavity photons in a microfluidic cavity platform. The resulting spectra exhibit a resolved doublet, power- and concentration-dependent redistribution of spectral weight, and linewidth narrowing indicative of cavity-modified dissipation. Quantitative analysis reveals collective square-root of N-scaling of the coupling strength, with cooperativity and splitting-to-linewidth ratios exceeding unity, consistent with the onset of strong collective coupling driven by the vibrational molecular mode. A microscopic nonequilibrium analysis further indicates that the relaxation timescale toward the Frohlich polariton state is on the order of 1-10 microseconds. These findings identify terahertz cavities as a platform for stabilizing and controlling collective molecular vibration dynamics and open opportunities for cavity-engineered vibrational spectroscopy, label-free biosensing and photonic control of energy transport in complex biomolecular systems.

cond-mat.other↗

arXiv2025

Resonant Dyakonov-Shur Magnetoplasmons in Graphene Terahertz Photodetectors

Graphene plasmons confine incident terahertz fields far below the diffraction limit and, when hosted by a gate-defined Fabry-Perot cavity, enable electrically tunable, frequency-selective photodetectors. In a magnetic field, these plasmons hybridize with the cyclotron motion to form magnetoplasmons, offering a platform for fundamental studies and for nonreciprocal, spectrally selective, ultrasensitive terahertz photonics. However, implementing magnetoplasmon-assisted resonant transistors at terahertz frequencies has remained challenging so far. Here we use gate-dependent, on-chip terahertz photocurrent spectroscopy combined with a perpendicular magnetic field to resolve and probe the evolution of resonant magnetoplasmons in antenna-coupled monolayer and bilayer graphene TeraFETs. In monolayer graphene the dispersion reflects the Dirac nature of the carriers, exhibiting a non-monotonic density dependence due to the interplay of plasma resonance and cyclotron motion, with an inflection point at maximal plasmon-cyclotron coupling. In contrast, in bilayer graphene we recover and map a magnetoplasmon dispersion consistent with the conventional Schr\"odinger-type picture. These results establish graphene TeraFET devices as a robust on-chip platform for resonant magnetoplasmonics at terahertz frequencies, enabling magnetically programmable, frequency-selective photonics and opening avenues toward photodetectors with enhanced sensitivity.

cond-mat.mes-hall↗

arXiv2024

Terahertz and gigahertz magneto-ratchets in graphene-based 2D metamaterials

We report on the observation and study of the magneto-ratchet effect in a graphene-based two-dimensional metamaterial formed by a graphite gate that is placed below a graphene monolayer and patterned with an array of triangular antidots. We demonstrate that terahertz/gigahertz excitation of the metamaterial leads to sign-alternating magneto-oscillations with an amplitude that exceeds the ratchet current at zero magnetic field by orders of magnitude. The oscillations are shown to be related to the Shubnikov-de Haas effect. In addition to the giant ratchet current oscillations we detect resonant ratchet currents caused by the cyclotron and electron spin resonances. The results are well described by the developed theory considering the magneto-ratchet effect caused by the interplay of the near-field radiation and the nonuniform periodic electrostatic potential of the metamaterial controlled by the gate voltages.

cond-mat.mes-hall↗