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DOI: 10.1117/12.2320277
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Metasurfaces have been used for light manipulation and control, from the point of view of planar optics or polarization control, or non-linear light extraction. The properties of metasurfaces is rooted in the presence of resonant basic elements which are responsible for strongly confined electromagnetic surface modes. We propose to use these modes to enhance light-matter interaction in the vicinity of the surface by considering hybrid structure made of a thin layer, such as a 2D quantum material or a thin film with embedded quantum dots. A semi-classical theory will be proposed along with some functionalities attainable with the device.

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Ref Arxiv: 1804.07472
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This note is a reply to the paper (arXiv:1801.0559v2): " The gauge-invariant Lagrangian, the Power-Zienau-Woolley picture, and the choices of field momenta in nonrelativistic quantum electrodynamics" by G. Kónya, et al.See also our first reply (arXiv:1804.07472v1) in response to their initial comment "The equivalence of the Power-Zineau-Woolley picture and the Poincaré gauge from the very first principles " ( arXiv:1801.05590v1) ————————————– In a recent paper, we have shown that the Power-Zienau-Woolley Hamiltonian does not derived from the minimal-coupling hamiltonian with the help of a gauge transformation. This result has been challenged by G. Kónya and al. They first claim an error [arXiv:1801.05590v1] followed by a subsequent allegation that the Power-Zienau-Woolley hamiltonian can be derived starting from the electromagnetic action.We do not share their conclusions and show in two back-to-back replies [arXiv:1804.07472v1 followed by this note] that their successive statements are not correct.

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Ref Arxiv: 1708.05238
DOI: 10.1103/PhysRevB.97.035303
WoS: WOS:000419615100007
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15 Citations
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We addressed the carrier dynamics in so-called G-centers in silicon (consisting of substitutional-interstitial carbon pairs interacting with interstitial silicons) obtained via ion implantation into a silicon-on-insulator wafer. For this point defect in silicon emitting in the telecommunication wavelength range, we unravel the recombination dynamics by time-resolved photoluminescence spectroscopy. More specifically, we performed detailed photoluminescence experiments as a function of excitation energy, incident power, irradiation fluence and temperature in order to study the impact of radiative and non-radiative recombination channels on the spectrum, yield and lifetime of G-centers. The sharp line emitting at 969 meV ($\sim$1280 nm) and the broad asymmetric sideband developing at lower energy share the same recombination dynamics as shown by time-resolved experiments performed selectively on each spectral component. This feature accounts for the common origin of the two emission bands which are unambiguously attributed to the zero-phonon line and to the corresponding phonon sideband. In the framework of the Huang-Rhys theory with non-perturbative calculations, we reach an estimation of 1.6$\pm$0.1 $\angstrom$ for the spatial extension of the electronic wave function in the G-center. The radiative recombination time measured at low temperature lies in the 6 ns-range. The estimation of both radiative and non-radiative recombination rates as a function of temperature further demonstrate a constant radiative lifetime. Finally, although G-centers are shallow levels in silicon, we find a value of the Debye-Waller factor comparable to deep levels in wide-bandgap materials. Our results point out the potential of G-centers as a solid-state light source to be integrated into opto-electronic devices within a common silicon platform.

Commentaires: . Réf Journal: Phys. Rev. B 97, 035303 (2018)

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PMID 28894205
DOI: 10.1038/s41598-017-11076-5
WoS: 000410063400044
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This article deals with the fundamental problem of light-matter interaction in the quantum theory. Although it is described through the vector potential in quantum electrodynamics, it is believed by some that a hamiltonian involving only the electric and the magnetic fields is preferable. In the literature this hamiltonian is known as the Power-Zienau-Woolley hamiltonian. We question its validity and show that it is not equivalent to the minimal-coupling hamiltonian. In this article, we show that these two hamiltonians are not connected through a gauge transformation. We find that the gauge is not fixed in the Power-Zienau-Woolley hamiltonian. The interaction term is written in one gauge whereas the rest of the hamiltonian is written in another gauge. The Power-Zienau-Woolley hamiltonian and the minimal-coupling one are related through a unitary transformation that does not fulfill the gauge fixing constraints. Consequently, they predict different physical results. In this letter, we provide the correct quantum theory in the multipolar gauge with a hamiltonian involving only the physical fields.

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DOI: 10.1126/science.aam9353
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37 Citations
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Two-boson interference, a fundamentally quantum effect, has been extensively studied with photons through the Hong-Ou-Mandel effect and observed with guided plasmons. Using two freely propagating surface plasmon polaritons (SPPs) interfering on a lossy beam splitter, we show that the presence of loss enables us to modify the reflection and transmission factors of the beam splitter, thus revealing quantum interference paths that do not exist in a lossless configuration.We investigate the two-plasmon interference on beam splitters with different sets of reflection and transmission factors. Through coincidence-detection measurements, we observe either coalescence or anti-coalescence of SPPs.The results show that losses can be viewed as a degree of freedom to control quantum processes.