Source: https://www.institut-langevin.espci.fr/valentina_krachmalnicoff?lang=fr
Timestamp: 2019-04-20 06:55:43+00:00

Document:
Valentina KRACHMALNICOFF is a CNRS researcher scientist at Institut Langevin. She obtained a PhD degree from University Paris-Sud in 2009 with a thesis on quantum atom optics experiments (PhD thesis pdf) done under the supervision of A. Aspect and C. Westbrook. In 2010, she joined the Langevin Institute (group of Prof. R. Carminati) as a postdoctoral fellow to develop a novel nanophotonic experimental setup for studying the influence of a complex environment on spontaneous emission. In 2012, she joined the Langevin Institute as a CNRS research scientist. Her research work concerns the study of the near-field interaction between fluorescent nano-emitters with nanostructured plasmonic or dielectric samples and optical transport properties in nanostructured media. She has a strong experience in fluorescence intensity and decay rate measurements of nano-objects grafted on the tip of a scanning probe microscope, and in nano-manipulation.
In 2007 she was laureate of the prize L’Oréal France – UNESCO “For Women in Science”.
In 2017, she was awarded the CNRS Bronze Medal. The CNRS Bronze Medal recognizes a researcher’s first work, which makes that person a specialist with talent in a particular field.
Probing near-field light-matter interactions with single-molecule lifetime imaging.
Bouchet, D., J. Scholler, G. Blanquer, Y. De Wilde, I. Izeddin, and V. Krachmalnicoff.
Optica 6, no. 2 (2019): 135–138.
Résumé: © 2019 Optical Society of America. Nanophotonics offers a promising range of applications spanning from the development of efficient solar cells to quantum communications and biosensing. However, the ability to efficiently couple fluorescent emitters with nanostructured materials requires one to probe light-matter interactions at a subwavelength resolution, which remains experimentally challenging. Here, we introduce an approach to performsuperresolved fluorescence lifetime measurements on samples that are densely labeled with photo-activatable fluorescent molecules. The simultaneous measurement of the position and the decay rate of the molecules provides direct access to the local density of states (LDOS) at the nanoscale.We experimentally demonstrate the performance of the technique by studying the LDOS variations induced in the near field of a silver nanowire, and we show via a Cramér-Rao analysis that the proposed experimental setup enables a single-molecule localization precision of 6 nm.
Polarization Control of Linear Dipole Radiation Using an Optical Nanofiber.
Joos, M., C. Ding, V. Loo, G. Blanquer, E. Giacobino, A. Bramati, V. Krachmalnicoff, and Q. Glorieux.
Physical Review Applied 9, no. 6 (2018).
Résumé: © 2018 American Physical Society. We experimentally demonstrate that a linear dipole is not restricted to emit linearly polarized light, provided that it is embedded in the appropriate nanophotonic environment. We observe emission of various elliptical polarizations by a linear dipole, including circularly polarized light, without the need for birefringent components. We further show that the emitted state of polarization can theoretically span the entire Poincaré sphere. The experimental demonstration is based on elongated gold nanoparticles (nanorods) deposited on an optical nanofiber and excited by a free-space laser beam. The light directly collected in the guided mode of the nanofiber is analyzed in regard to the azimuthal position and orientation of the nanorods, observed by means of scanning electron microscopy. We demonstrate a mapping between purely geometrical degrees of freedom of a light source and all polarization states that could open the way to alternative methods for polarization control of light sources at the nanoscale.
Near-Field and Far-Field Thermal Emission of an Individual Patch Nanoantenna.
Li, C., V. Krachmalnicoff, P. Bouchon, J. Jaeck, N. Bardou, R. Haïdar, and Y. De Wilde.
Physical Review Letters 121, no. 24 (2018).
Résumé: © 2018 American Physical Society. The far-field spectral and near-field spatial responses of an individual metal-insulator-metal nanoantenna are reported, using thermal fluctuations as an internal source of the electromagnetic field. The far-field spectra, obtained by combining Fourier transform infrared spectroscopy with spatial modulation based on a light falloff effect in a confocal geometry, have revealed two distinct emission peaks attributed to the excitation of the fundamental mode of the nanoantenna at two distinct wavelengths. Superresolved near-field images of the thermally excited mode have been obtained by thermal radiation scanning tunneling microscopy. Experimental results are supported by numerical simulations showing that it is possible to excite the same mode at different wavelengths near a resonance of the insulating dielectric material forming the antenna.
Sub-poissonian number differences in four-wave mixing of matter waves.
Jaskula, J. - C., M. Bonneau, G. B. Partridge, V. Krachmalnicoff, P. Deuar, K. V. Kheruntsyan, A. Aspect, D. Boiron, and C. I. Westbrook.
Physical Review Letters 105, no. 19 (2010).
Résumé: We demonstrate sub-Poissonian number differences in four-wave mixing of Bose-Einstein condensates of metastable helium. The collision between two Bose-Einstein condensates produces a scattering halo populated by pairs of atoms of opposing velocities, which we divide into several symmetric zones. We show that the atom number difference for opposing zones has sub-Poissonian noise fluctuations, whereas that of nonopposing zones is well described by shot noise. The atom pairs produced in a dual number state are well adapted to sub-shot-noise interferometry and studies of Einstein-Podolsky-Rosen-type nonlocality tests. © 2010 The American Physical Society.
Imaging light scattered by a subwavelength nanofiber, from near field to far field.
Loo, V., G. Blanquer, M. Joos, Q. Glorieux, Y. De Wilde, and V. Krachmalnicoff.
Optics Express 27, no. 2 (2019): 350–357.
Résumé: © 2019 Optical Society of America. We present a direct experimental investigation of the optical field distribution around a suspended tapered optical nanofiber by means of a fluorescent scanning probe. Using a 100 nm diameter fluorescent bead as a probe of the field intensity, we study interferences made by a nanofiber (400 nm diameter) scattering a plane wave (568 nm wavelength). Our scanning fluorescence near-field microscope maps the optical field over 36 µm2, with λ/5 resolution, from contact with the surface of the nanofiber to a few micrometers away. Comparison between experiments and Mie scattering theory allows us to precisely determine the emitter-nanofiber distance and experimental drifts.
Anisotropy in s-wave Bose-Einstein condensate collisions and its relationship to superradiance.
P. Deuar, J.-C. Jaskula, M. Bonneau, V. Krachmalnicoff, D. Boiron, C. I. Westbrook, K. V. Kheruntsyan.
Phys. Rev. A 90 (2014): 033613.
J.-C. Jaskula, M. Bonneau, G. B. Partridge, V. Krachmalnicoff, P. Deuar, K. V. Kheruntsyan, A. Aspect, D. Boiron, C. I. Westbrook.
Phys. Rev. Lett. 105 (2010): 190402.
Spontaneous Four-Wave Mixing of de Broglie Waves : Beyond Optics.
V. Krachmalnicoff, J.-C. Jaskula, M. Bonneau, V. Leung, G. B. Partridge, D. Boiron, C. I. Westbrook, P. Deuar, P. Zin, M. Trippenbach, and K. V. Kheruntsyan.
Phys. Rev. Lett. 104 (2010): 150402.
Atomic four-wave mixing via condensate collisions.
A. Perrin, C. M. Savage, D. Boiron, V. Krachmalnicoff, C. I. Westbrook, K. Kheruntsyan.
New J. Phys. 10 (2008): 045021.
Hanbury Brown and Twiss correlations in atoms scattered from colliding condensates.
K. Mølmer, A. Perrin, V. Krachmalnicoff, V. Leung, D. Boiron, A. Aspect and C. I. Westbrook.
Phys. Rev. A 77 (2008): 033601.
Atom-atom correlations in spontaneous four wave mixing of two colliding Bose-Einstein Condensates.
A. Perrin, H. Chang, V. Krachmalnicoff, M. Schellekens, D. Boiron, A. Aspect, C. I. Westbrook.
Phys. Rev. Lett. 99 (2007): 150405.
Comparison of the Hanbury Brown-Twiss effect for bosons and fermions.
T. Jeltes, J. M. McNamara, W. Hogervorst, W.Vassen, V. Krachmalnicoff, M. Schellekens, A. Perrin, H. Chang, D. Boiron, A. Aspect, C. I. Westbrook.
Present status of the fine structure frequencies of the 2[]P Helium level.
G. Giusfredi, P. De Natale, D. Mazzotti, P. Cancio Pastor, C. de Mauro, L. Fallani, G. Hagel, V. Krachmalnicoff, M. Inguscio.
Can. J. Phys. 83 (2005): 301-310.

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