Nanophotonics refers to the unique interactions of light (photonics) and materials at the nanometer scale. Nanometer sized metals (e.g. gold, silver, copper) exhibit extremely high electric field enhancements when excited by laser light, leading to unique opportunities in sensing and therapy in cancer applications. Therapeutically, this interaction can be used to generate heat and mechanical shock waves (nanobubbles) that serve to release drugs, denature proteins, or disrupt cell membranes. We’ve demonstrated these effects can illicit a specific type of cell death that stimulates the body’s immune system to fight cancer in models of breast cancer and melanoma. Diagnostically, these nanomaterials enable a sensing platform using surface enhanced Raman scattering (SERS) that greatly enhances the detection ability of molecules near the particle surface. We are developing implantable devices with SERS sensors to monitor patients at risk for cancer recurrence after treatments.

Memory effects in disordered matter – granular suspensions, ferromagnets, crumpled paper…– can be described as pathways between the different states visited by the system upon driving. However, due to their complexity, we lack strategy to experimentally probe, understand and control such pathways in most memory forming systems.

We introduce mechanical driving of corrugated elastic sheets to precisely observe and manipulate complex, multi-step pathways. These systems respond to simple 1D forcing via sequences of elastic snap-through instabilities, leading to complex– yet controlled–deformation pathways, reminiscent of memory effects. In particular we use manipulations of the boundaries to elicit a multitude of pathways from a single sample, and show how interactions between the instabilities lead to new pathways, akin to information processing.

Supersymmetric extensions of conformal gravity have been known for a long time. In four spacetime dimensions, N=4 conformal supergravity is the maximally supersymmetric theory of this type. While the underlying multiplet of fields and their full non-linear transformations rules were already derived 40 years ago, no complete invariant action had been constructed so far. I will present the most general class of actions which turns out to be characterized by a holomorphic function of the scalar fields. This deviates from the non-maximally supersymmetric cases for which there is a unique action. I will then discuss how these results can be used to study certain higher-derivative couplings of N=4 (gauged) Poincaré supergravities.

Higgs precision measurements and resonance searches at the LHC have made sharper than ever the electroweak naturalness problem. In response, the particle physics community has begun to question symmetry-based solutions. We provide a new perspective by proposing a symmetry-based framework which does not require any fine-tuning to comply with current experimental observations. This is achieved by abandoning the additional constraint of minimality typically imposed on the structure of symmetry breaking. Single-Higgs coupling deviations of a few percent and trilinear self-coupling deviations of order one are irreducible in the natural parameter space.

Pierre Verlot (ILM, Lyon)
Séminaire le 12/07 à 14h (Bâtiment 5 salle 5.201)
l’Optomécanique Quantique
Quantum optomechanics at room temperature: A nanomechanical endeavour?


Optomechanics is the field investigating the reciprocal interaction between electromagnetic and mechanical degrees of freedom1.

Recently, impressive progress has been accomplished in the field, notably with the demonstration of multiple systems operating in the quantum regime of the
optomechanical interaction2–4. This in great part relies on the extreme miniaturization of the mechanical devices, which enables drastic decrease of the thermal noise, at the benefit of quantum effects5,6.

So far however, the quantum regime of the optomechanical interaction has essentially been evidenced at liquid helium temperature or below and remains remote to ambient conditions. In this talk, I will present novel approaches raising the realistic perspective of operating optomechanical systems deep in the quantum regime and at room temperature. I will primarily focus on the fabrication and optomechanical characterization of a novel hybrid carbon nanotube-based approach7–9 which is found to a record low thermal force noise at room temperature, while fully preserving sensing capabilities. I will also discuss the role of non-linearities and corresponding sensing limitations for the sensitivity of
those devices at ambient temperature. Last, I will introduce recent results on a novel quantum hybrid optomechanical approach, based on the use of gram-scale rare-earth ion doped crystal10,11, which appears very promising as for reaching the quantum regime at room temperature and under very robust conditions12.

References
1. Aspelmeyer, M., Kippenberg, T. J. & Marquardt, F. Cavity optomechanics. Reviews of Modern Physics 86,1391,(2014).
2. Chan, J. et al. Laser cooling of a nanomechanical oscillator into its quantum ground state. Nature 478, 89–92 (2011).
3. Purdy, T. P., Peterson, R. W. & Regal, C. A. Observation of radiation pressure shot noise on a macroscopic object. Science 339, 801–804 (2013).
4. Riedinger, R. et al. Remote quantum entanglement between two micromechanical oscillators. Nature 556, 473–477 (2018).
5. Moser, J. et al. Ultrasensitive force detection with a nanotube mechanical resonator. Nature
nanotechnology 8, 493–496 (2013).
6. Moser, J., Eichler, A., Güttinger, J., Dykman, M. I. & Bachtold, A. Nanotube mechanical resonators with quality factors of up to 5 million. Nature nanotechnology 9, 1007–1011 (2014).
7. Tsioutsios, I., Tavernarakis, A., Osmond, J., Verlot, P. & Bachtold, A. Real-time measurement of nanotube resonator fluctuations in an electron microscope. Nano letters 17, 1748–1755 (2017).
8. Tavernarakis, A. et al. Optomechanics with a hybrid carbon nanotube resonator. Nature communications 9, 1–8 (2018).
9. Gruber, G. et al. Mass sensing for the advanced fabrication of nanomechanical resonators. Nano letters 19, 6987–6992 (2019).
10. Louchet-Chauvet, A., Ahlefeldt, R. & Chanelière, T. Piezospectroscopic measurement of high-frequency vibrations in a pulse-tube cryostat. Review of Scientific Instruments 90, 034901 (2019).
11. Louchet-Chauvet, A. & Chanelière, T. Limits to the sensitivity of a rare-earth-enabled cryogenic vibration sensor. arXiv preprint arXiv:2112.03713 (2021).
12. Louchet-Chauvet, A., Verlot, P., Poizat, J.-P. & Chanelière, T. Optomechanical backaction processes in a bulk rare-earth doped crystal. arXiv preprint arXiv:2109.06577 (2021).

Buiding up hierarchical organizations is still challenging because one have to design self-assembly mechanismes at various length scales and with similar time scales. Two nanoparticle systems are presented. The former system (Fig. 1) is a interplaying between drying processes at nanometric scale (colloidal crystallization) and millimetric scale (Maze Formation within micropatterned surfaces). The second system is the slow crystalisation of polydisperse Ludox®. In both cases, entropy plays an important role with (i) Onsager “Forces” that ease the nematic order between nanorods, and with (ii) mixing entropy in cluster phases.
The former system can be exploited to generate well defined hierarchical organizations with new photophysical properties (superradiance). The Laves phase (Fig. 2) observed in the second system is only the first generation of a clustering process that can generate BCC and AB13 phases of rhombicuboctahedron with more than 500 nanoparticles per unit cell.

Keywords: nanoparticles superlatices, Onsager, mixing entropy, drying, crystallization tolerance.
References
[1] Hamon, et al, ACS. Nano, 2012, 6(5), 4137-4146. Bizien, et al, Small, 2014, 10(18), 3707–3716. Panizza, et al, Phys. Rev. Lett. 2018 121(20), 078002.. Bizien, et al, J. Nanomaterials, 2021, 1790976.
[2] Cabane, et al, Phys. Rev. Lett. 2016, 116(20), 208001. Botet, et al, Faraday Dis., 2016, 186, 229-240. Unpublished Results.

MassTech Collaborative has helped to make the Commonwealth a beacon for advanced manufacturing. In partnership with the AIM Photonics manufacturing institute, MassTech has launched five Laboratories for Education and Application Prototypes (LEAPs) within academic institutions spread widely across Massachusetts, to develop a skilled workforce in integrated photonics. Hands-on and in-person workshops, bootcamps and laboratory courses are offered at these LEAPs to learners from academia, industry, and the government.



In addition to teaching how to test Photonic Integrated Circuits (PICs), each LEAP has a specialized focus. The LEAP @ Massachusetts Institute of Technology focuses on Electronic-Photonic Packaging (EPP), the LEAP @ Worcester Polytechnic Institute – Quinsigamond Community College (WPI-QCC) on bio-medical photonics applications, LEAP @ Stonehill College on materials testing and photodetectors, LEAP@ Bridgewater State University (BSU) on high power and ultrafast near- and mid-infrared lasers and quantum-devices, and finally the LEAP @ Western New England (WNE) University on lasers and RF photonics.

In this talk I will focus on the LEAP at BSU and some of the research and opportunities we could offer to colleagues in Montpellier in research, pedagogical strategies and opportunities and ideas with industry prototyping. In particular, I will present some of the work we have been doing to characterize the nonlinear third order coefficients in waveguide structures (fibers and photonic integrated circuits). The technique, called D-Scan (dispersive scan) uses the temporal analogous of the Z-Scan, treating the waveguides as temporal lenses, and consists in measuring the output spectral broadening of transmitted pulses for various dispersion coefficients φ (2) applied to the injected pulses.