arXiv subjects

A. Leray

Publications and source records attributed to A. Leray.

5 recordsLinked to original sources

arXiv2026

Single plasmon transport in one dimensional nanowire

We introduce a unified theoretical framework for single-plasmon transport in one-dimensional nanowires, bridging the quantized electromagnetic Green's tensor formalism with effective non-Hermitian Hamiltonian models. This approach naturally incorporates propagating surface plasmon polaritons, high-order modes dissipative channels, and intrinsic losses. We investigate both the stationary regime and the spatio-temporal dynamics of a single-plasmon pulse travelling through an atomic chain coupled to a dispersive nanowire. We analyze modal contributions to reflection and transmission spectra for quantum emitter coupled to a silver nanowire, a configuration proposed as a single-plasmon transistor, and we demonstrate that optimized multi-emitter systems offer significant advantages. In case of one quantum emitter coupled to a silver nanowire at telecom wavelengths, we predict a single-plasmon transmittivity down to 7\% under realistic conditions, and an atomic qubit population of 12\%. Extension to multi-emitter systems using a L\"owdin orthogonalization procedure enables a consistent treatment of collective interactions. We show that optimized positioning with just five emitters enhances plasmon modulation, achieving a transmittivity of 2\% but also reduces coupling losses to one-third compared to the single-emitter case. Our results establish a robust foundation for analyzing and designing plasmonic waveguide quantum electrodynamics systems.

physics.optics↗

arXiv2024

Nano antenna-assisted quantum dots emission into high-index planar waveguide

Integrated quantum photonic circuits require the efficient coupling of photon sources to photonic waveguides. Hybrid plasmonic/photonic platforms are a promising approach, taking advantage of both plasmon modal confinement for efficient coupling to a nearby emitter and photonic circuitry for optical data transfer and processing. In this work, we established directional quantum dot (QD) emission coupling to a planar TiO$_2$ waveguide assisted by a Yagi-Uda antenna. Antenna on waveguide is first designed by scaling radio frequency dimensions to nano-optics, taking into account the hybrid plasmonic/photonic platform. Design is then optimized by full numerical simulations. We fabricate the antenna on a TiO$_2$ planar waveguide and deposit a few QDs close to the Yagi-Uda antenna. The optical characterization shows clear directional coupling originating from antenna effect. We estimate the coupling efficiency and directivity of the light emitted into the waveguide.

cond-mat.mes-hall↗

arXiv2024

Self-induced light emission in solid-state memristors replicates neuronal biophotons

Key pre-synaptic and post-synaptic biological functions have been successfully implemented in various hardware systems. A noticeable example are neuronal networks constructed from memristors, which are emulating complex electro-chemical biological dynamics such a neuron's efficacy and plasticity. Neurons are highly active cells, communicating with chemical and electrical stimuli, but also emit light. These photons are suspected to be a complementary vehicle to transport information across the brain. Here, we show that a memristor also releases photons akin to the production of neuronal light. Critical attributes of so-called biophotons such as self-generation, origin, stochasticity, spectral coverage, sparsity and correlation with the neuron's activity are replicated by our solid-state approach. Our findings further extend the emulating capability of a memristor to encompass neuronal biophoton emission and open the possibility to construct a bimodal electro-optical platform with the assistance of atomic-scale devices capable of handling electrons and photons as information carriers.

cond-mat.mes-hall↗

arXiv2022

Vectorial probing of electric and magnetic transitions in variable optical environments and vice-versa

We use europium doped single crystalline NaYF$_4$ nanorods for probing the electric and magnetic contributions to the local density of optical states (LDOS). Reciprocically, we determine intrinsic properties of the emitters (oscillator strength, quantum yield) by comparing their measured and simulated optical responses in front of a mirror. We first experimentally determine the specifications of the nanoprobe (orientation and oscillator strength of the electric and magnetic dipoles moments) and show significant orientation sensitivity of the branching ratios associated with electric and magnetic transitions. In a second part, we measure the modification of the LDOS in front of a gold mirror in a Drexhage's experiment. We discuss the role of the electric and magnetic LDOS on the basis of numerical simulations, taking into account the orientation of the dipolar emitters. We demonstrate that they behave like degenerated dipoles sensitive to polarized partial LDOS.

cond-mat.mes-hall↗

arXiv2021

Measuring the magnetic dipole transition of single nanorods by spectroscopy and Fourier microscopy

Rare-earth doped nanocrystals possess optical transitions with significant either electric or magnetic dipole characters. They are of strong interest for understanding and engineering light-matter interactions at the nanoscale with numerous applications in nanophotonics. Here, we study the $^5$D$_0\rightarrow ^7$F$_1$ transition dipole vector in individual NaYF$_4$:Eu$^{3+}$ nanorod crystals by Fourier and confocal microscopies. {Single crystalline host matrix leads to narrow emission lines at room temperature that permit to separate Stark sublevels resulting from the crystal field splitting}. We observe a fully magnetic transition and {low variability} of the transition dipole orientation over several single nanorods. We estimate the proportion of the dipole transitions for the Stark sublevels. We also determine an effective altitude of the rod with respect to the substrate. The narrow emission lines characteristic of NaYF$_4$:Eu$^{3+}$ ensure well-defined electric or magnetic transitions, and are thus instrumental for probing locally their electromagnetic environment by standard confocal microscopy.

cond-mat.mes-hall↗