Optical Characterization at the Nanoscale


Optical Characterization at the NanoscaleTitle: Optical Characterization at the Nanoscale.
When: Wednesday, February 07, (2018), 15:00.
Place: Department of Theoretical Condensed Matter Physics, Faculty of Science, Module 5, Seminar Room (5th Floor).
Speaker: Massimo Gurioli, Department of Physics and Astronomy, University of Florence, Sesto Fiorentino (FI), Italy.

The tremendous progress in nanophotonics towards efficient quantum emitters at the nanoscace requires investigation tools able to access the detailed features of the both sources and optical modes with deep-subwavelength spatial resolution. This scenario has motivated the development of different nanoscale optical imaging techniques.

In this contribution, we will overview our activity in exploiting near field microscopy for optical characterization at the nanoscale, both for semiconductor nanostructures and photonics nanoresonators. We will show that the scanning near field optical micro-scopy (SNOM) is a powerful method to access the excitons confined at the nanoscale and to image the electric-magnetic field in nanophotonics.

In the first part we will present experi-ments on carbon nanotubes where the confined excitons are mapped along the micrometer long tube extension, evincing localization and tube bending [1,2]. Exemples are given in Figure 1.

In the second part we will discuss a novel technique involving the combination of scanning near-field optical microscopy with resonant scattering spectroscopy. The scheme of a RS-SNOM measurement on a microring is given in Figure 2. Our approach enables imaging the electric and magnetic field intensity (including phase, amplitude and polarization) in nano-resonators with sub-wavelength spatial resolution (λ/20) [3-8]. We conclude with recent results on the exploitation of our resonant scattering SNOM for addressing the exceptional points in photonics.

References

  1. F. Sarti, et al. Nanoresearch 9, 2478 (2016).
  2. F. La China, et al. JAP, 120, 123110, (2016).
  3. F. Riboli, et al. Nat. Materials 13: 720 (2014).
  4. N. Caselli, et al. Light: Science & Applications 4, e326, (2015).
  5. N. Caselli, et al. Scientific Reports 5, 9606 (2015).
  6. F. La China, et al. ACS Photonics 2, 1712 (2015).
  7. N. Caselli, et al. APL Photonics 1, 041301 (2016).
  8. N. Caselli, et al. APL 110, 081102 (2017).
  9. N. Caselli, et al. submitted to Nat. Materials.



Bubbles, Drops and Vesicles: The Charm of Microfluidics


Bubbles, Drops and Vesicles: The Charm of MicrofluidicsTitle: Bubbles, Drops and Vesicles: The Charm of Microfluidics.
When: Friday, February 02, (2018), 12:00.
Place: Department of Theoretical Condensed Matter Physics, Faculty of Science, Module 5, Seminar Room (5th Floor).
Speaker: Laura R. Arriaga, Universidad Complutense de Madrid, Spain.

The exquisite control over the flow of fluids afforded by microfluidic technologies enables the design of materials with precise properties. In this talk, I will show some examples. For example, flowing air into a liquid enables the production of foams made bubble-­‐by-­‐bubble; these can be solidified, resulting in controlled porous architectures [1]. Moreover, flowing a liquid into a second immiscible liquid enables the production of emulsions consisting of drops; their surface can be used as a one-­‐pot system for synthesis, assembly and display of functional membrane proteins [2]. Furthermore, the incorporation of additional fluids enables the generation of controlled multiple emulsions; these afford many more possibilities for creating new materials. Among them, water-­‐in-­‐perfluorocarbon-­‐in-­‐water double emulsion droplets can be used for acoustic-­‐triggered release of payloads [3]. In addition, water-­‐in-­‐oil-­‐in-­‐ water double emulsion droplets with very thin shells can be used as templates for vesicle formation [4]. These vesicles are monodisperse in size, have uniform composition and a high encapsulation efficiency as the flow stream of the fluid that forms the vesicle core is completely separated from the outer fluid [5] these overcomes the limitations of vesicles produced by conventional methods. Despite bubbles and drops are all produced by microfluidics one at a time, I will also show that scaling up is possible [6].

References

  1. A. Testouri, L. R. Arriaga et al., Colloids and Surfaces A 413, 17-24, 2012.
  2. P. J. Yunker, H. Asaharac, K.-C. Hung, C. Landry, L. R. Arriaga et al. PNAS 113, 608-613, 2016.
  3. W. J. Duncanson, L. R. Arriaga et al., Langmuir 30, 13765-13770, 2014.
  4. L. R. Arriaga, S. S. Datta et al., Small 10, 950-956, 2014.
  5. B. Herranz-Blanco, L. R. Arriaga et al., Lab on a Chip 14, 1083-1086, 2014.
  6. L. R. Arriaga, E. Amstad and D. A. Weitz, Lab on a Chip 15, 3335-3340, 2015.



Superconductors and Quantum Information Preservation in Black Holes


Superconductors and Quantum Information Preservation in Black Holes

Title: Superconductors and Quantum Information Preservation in Black Holes.
When: Tuesday, January 30, (2018), 12:00.
Place: Department of Theoretical Condensed Matter Physics, Faculty of Science, Module 5, Seminar Room (5th Floor).
Speaker: Andrew N. Jordan, Department of Physics and Astronomy, University of Rochester, New York, USA.

This talk will demonstrate how the quantum information entering black holes is analogous to quantum information entering a superconductor. The analogy maps the interior of a black hole to a superconductor, and the exterior of the black hole to a normal metal. We show that the metal-superconductor interface can be thought of as an event horizon: The proximity effect in superconductor-metal interfaces (where Cooper pairs tend to form in the normal metal) is analogous to electron-positron creation at the event horizon in black-holes, which gives rise to Hawking radiation. Existing ideas of preserving quantum information entering black holes – the Preskill informational mirror, and the Horowitz-Maldacena mechanism for black-hole evaporation (which necessitates a unique final state for the black-hole), can be exactly realized as quantum information swapping or transfer using Andreev reflection processes. I will present mesoscopic physics analogs to wormholes with crossed Andreev reflection – and conjecture that the BCS ground state also describes the final quantum state of a black hole.

References

  1. Andreev reflections and the quantum physics of black holes, Sreenath K. Manikandan and Andrew N. Jordan, Phys. Rev. D 96, 124011, (2017).



Linux Administration Course


Linux Administration Course

The objectives of this course are to learn how to install Linux from a single computer to a HPC cluster. This course has been created to provide students with the necessary skills to work as Linux system administrators in research groups.

For more information please visit the CCC’s website.