Dye-loaded fluorescent polymeric nanoparticles (NPs) appear as an attractive alternative to inorganic NPs, such as quantum dots (QDots). Confining large number of dyes with bulky counterions within small polymeric nanoparticles makes the latter particularly bright and enable phenomenon of giant light-harvesting. Functionalization of these NPs with DNA yields FRET-based color switching nanoprobes for nucleic acids with single-molecule sensitivity and compatibility with RGB camera of a smartphone, important for cancer diagnostics. We also found that the energy transfer between two NPs connected by DNA duplexes does not follow canonical Förster law, allowing efficient long-range FRET at distances up to 20 nm, important for construction of ultrasensitive biosensors. When applied to cells, the small size of NPs was found essential for their free diffusion in cytosol and detection of intracellular RNA.^[8] At the animal level, the high brightness of NPs enabled single-particle tracking in the mice brain and visualization of crossing the blood-brain barrier. The developed small dye-loaded polymeric NPs open the route to ultrabright tools for sensing and tracking of biomolecules in biology and medicine.

Andrey Klymchenko obtained his PhD degree in 2003 from Kyiv National University. Then, he worked as post-doctoral fellow in the University of Strasbourg and Catholic University of Leuven. Then, he joined CNRS in 2006, received CNRS Bronze Medal in 2010 and was promoted to Director of Research in 2014. In 2015, he obtained ERC consolidator grant BrightSens. In 2021, he received Prix du Dr et de Mme Henri LABBE from French Academy of Sciences and he was elected a member of Academia Europaea. He is a leader of “Nanochemistry and Bioimaging” group and a co-founder of a start-up BrightSens Diagnostics. He is a co-author of over 250 peer-reviewed articles and 12 patents.

Abstract: i) Magnetic Skyrmions are chiral particles and the diffusion is accompanied by a rotational motion which can be expressed by taking the diffusion coefficient as a tensor [1]. A skyrmion in a two-dimensional harmonic potential will rotate infinitely in the thermal equibirum. This rotation has zero angular momentum and does not violate the Bohr-Van Leeuwen’s theorem [2].

ii) From the LLG equation by taking the excitation of spin waves inside the skyrmion as the collective coordinates in addition to the center coordinate, it was shown that the center of magnetization has mass, but the center of charge has no mass [3].

iii) The information flow between two dipole-interacting skyrmions were obtained experimentaly. Analysis revealed that the system is not Markovian but hidden Markov system with a non-zero calculation power without consuming any energy in thermal equilibrium.

Acknowledgments We acknowledge to H. Mori, K. Emoto, S. Miki, M. Goto, H. Nomura and E. Tamura of Osaka University and R. Ishikawa of ULVAC Inc.. The project was supported by JSPS KAKENHI (S) JP20H05666 and JST CREST JPMJCR20C1.

References

[1] Y. Suzuki, S. Miki and E. Tamura, Physics Letters A, 413, (2021) 127603.

[2] S. Miki, Y. Jibiki, E. Tamura, M. Goto, M. Oogane, J. Cho, et al., J. Phys. Soc. Jpn., 90, 083601 (2021).

[3] Y. Suzuki, S. Miki, H. Nomura, E. Tamura, cond-mat, arXiv:2208.01835.

[4] R. Ishikawa, M. Goto, H. Nomura, and Y. Suzuki, Appl. Phys. Lett., 119, 072402 (2021).

Keywords: Skyrmion, Gyro-diffusion, Skyrmion mass, Hidden Markov system

Short bio:

In 1984, Suzuki graduated Tsukuba Univ. and started his carier at AIST. The thesis work was on the “MBE growth of the magnetic multilayers”. In 2003, he moved to Osaka Univ.. His research topics were “Magnetic Quantum well states”, “Magnetic tunnel junctions”, “spin-torque diode effect”, and “Voltage Control of Magnetic Anisotropy”.

He published about 400 papers and is getting about 20,000 citations.

From 1993 to 1994, he stayed at IEF-Universite Paris-sud as a “boursier”.

- Xin Zheng (C2N Photonics Department) - GRadien INdex (GRIN) optics in silicon photonics

- Junbum Park (C2N Nanoelectronics Department) - Full Band Monte Carlo simulation of 2D h-BN nanostructure for phonon transport based on ab initio calculation

- Kamel-Eddine Harabi (C2N Nanoelectronics Department) - Memristor Based Artificial Intelligence Accelerators using
In/Near Memory Computing Paradigm

- Cléophanie Brochard (C2N Materials Department) - Heat transport in Van der Waals heterostructures

An increased number of laser-based measurements in metrology are performed at the quantum-noise limit. One potential approach to enhance the signal-to-noise ratio in quantum-noise limited measurements is to increase the power of the light used. However, this straightforward approach comes with its own set of challenges and limitations. It can lead to thermal deformations in the optical beam path or even the destruction of the measurement sample and requires improved laser safety measures. To overcome these limitations, squeezed light emerged as a valuable solution. Squeezed light directly reduces the quantum noise, enabling enhanced precision in measurements without the need for excessively high light power. For example, as of 2019, all gravitational-wave observatories worldwide use squeezed vacuum states. In the talk, we will explain the concepts behind squeeze lasers in more detail and showcase how they effectively reduce quantum noise in measurements. Applications and recent advancements will also be discussed.

Photo : State-of the art squeeze laser developed at Uni Hamburg.

Hybrid nanomaterials are attractive for research on several types of gate-tunable quantum devices, e.g. superconducting qubits (gatemons), Andreev spin qubits, cryogenic switches, quantum limited amplifiers and for fundamental studies of bound states in superconductors and quantum dots [1]. Superconductor-semiconductor nanowires have been established as an essential platform in this research.

We firstly discuss the excitations and correlations arising in short chains of coupled quantum dots and superconducting islands in Al/InAs nanowires [2]. We then take a look beneath the surface of these devices, addressing advances in materials science where epitaxial growth, in situ fabrication and implementation of various superconductors have expanded the available parameter space for hybrid devices [3,4]. We will finally focus on opportunities arising from growth of multiple coupled nanowires [5].

[1] E. Prada et al., From Andreev to Majorana bound states in hybrid superconductor-semiconductor nanowires, Nature Rev. Phys. 2, 575 (2020)
[2] J.C. Estrada Saldana et al., Excitations in a superconducting Coulombic energy gap, Nature Comm. 13, 2243 (2022); Two Bogoliubov quasiparticles entangled by a spin, arxiv:2203.00104
[3] T. Kanne et al., Epitaxial Pb on InAs nanowires for quantum devices, Nature Nano. 16, 767 (2021)
[4] D. Carrad et al., Shadow Epitaxy for In Situ Growth of Generic Semiconductor-Superconductor Hybrids, Adv. Mat. 32, 1908411 (2020)
[5] T. Kanne et al., Double nanowires for hybrid quantum devices, Adv. Func. Mat. 32, 2107926 (2021)

Jesper Nygård is professor in experimental physics at the Niels Bohr Institute, Copenhagen where he was cofounder of the Center for Quantum Devices, and former head of the Nano-science Center. His research interests bridge growth of the semiconductor-superconductor hybrid materials by molecular beam epitaxy, electronic devices based on nanowires, and quantum transport. He currently resides in Grenoble where he holds a visiting chair of excellence at LANEF, Institut Néel, CNRS, and CEA (2022-25).

Intersubband transitions in n-doped coupled semiconductor quantum wells allow one to quantum-engineer materials with highly nonlinear optical response. The intersubband transitions in these materials are limited, however, to (mostly) electric field polarized perpendicular to the semiconductor heterostructure layers, which reduces their usefulness for free-space optics applications. This limitation can be removed and the already giant nonlinear optical response can be further enhanced if the intersubband transitions are coupled to electromagnetic modes of optical nanoresonators fabricated in semiconductor heterostructures to form intersubband polaritonic metasurfaces. In this presentation, I will present our latest results on developing intersubband polaritonic metasurfaces with record-high second- and third-order nonlinear optical responses. In particular, we will present metasurfaces designed for efficient mid-infrared second harmonic and difference-frequency generation with controllable phases of the nonlinear optical response and metasurfaces designed for saturable absorption and power limiting.

The magnetic tunnel junction (MTJ), a device comprised of two ferromagnetic electrodes with a thin (about 1 nm) insulating tunnel barrier in between, was first proposed in a Ph.D. thesis by Michel Jullière in 1975 and reached widespread commercialization nearly 30 years later as the read sensor in hard disk drives. MTJs became essential for data storage in consumer laptop and desktop computers, early-generation iPods, and now in data centers that store the information in “the Cloud.” The application of MTJs has expanded even further, becoming the storage element in non-volatile memory, first in toggle magnetic random access memory (MRAM) used in automotive applications and outer space, and now in the production of spin-transfer torque MRAM as a replacement for embedded flash memory. As computing capabilities advance and drive demand for high-performance memory, innovation in MTJs continues in order to deliver faster, high-density MRAM that can support last-level cache, in-memory computing, and artificial intelligence.

In this talk, I will describe the seminal discoveries that enabled MTJs for pervasive use in hard disk drives, MRAM, and magnetic sensors. As the demand for faster and higher density memory persists, still more breakthroughs are needed for MTJs contained in device pillars (or bits) just tens of nanometers in diameter. These advances require tuning of material properties at the atomic scale as well as across arrays of millions of bits in a memory chip. I will describe the magnetic properties of MTJs that are essential for high-performance MRAM and how to engineer these properties to deliver high spin-transfer torque efficiency and high data retention. In addition, I will describe the fabrication and individual addressing of MRAM bits in a 50nm full pitch array, as a step toward achieving high-density MRAM.

Tiffany S. Santos received S.B. and Ph.D. degrees in materials science and engineering from MIT. She is the Director of Non-Volatile Memory Materials Research at Western Digital, in San Jose, California where she leads a team working on materials for magnetic random access memory technology and other exploratory projects. She first joined the company in 2011, when it was previously known as Hitachi Global Storage Technologies, to work on research of granular FePt media for heat-assisted magnetic recording. Prior to working in industry, she was a Distinguished Post-Doctoral Fellow, and later an Assistant Scientist, at the Center for Nanoscale Materials of Argonne National Laboratory where she studied emergent phenomena at the interfaces of complex oxide heterostuctures. In 2009, she was awarded the L’Oréal USA Fellowship for Women in Science. In 2022, she became a Distinguished Lecturer of the IEEE Magnetics Society. She is General Chair of the 2025 MMM Conference to be held in Palm Beach, Florida.

The discovery of graphene has opened novel exciting opportunities in terms of functionalities and performances for spintronics devices. To date, it is mainly graphene properties for efficient in-plane spin transport which have been put forward.[1] We will present here experimental results concerning integration of graphene in vertical Magnetic Tunnel Junctions (MTJ), with strong technological potential.[2] We will show that a thin graphene passivation layer, directly integrated by low temperature catalyzed chemical vapor deposition (CVD),[3] allows to preserve a highly surface sensitive spin current polarizer/analyzer behavior. Characterizations of complete spin valves making use of graphene grown by CVD will be presented. The graphene layer prevents the oxidation of the ferromagnet, unlocking in turn the exploration of spin filtering phenomena at graphene/ferromagnet interfaces. We will discuss the measured experimental spin signals in light of bulk band structure spin filtering effect as usually observed with MgO, but also highlight the role of interfacial hybridization (a.k.a. spinterface) for spin selection with ab-initio calculations in support.[4] We will further discuss these observed spin filtering effects by analyzing results with other 2D materials (such as h-BN and WS2) integrated in MTJ devices. [5] Finally, we will expand the discussion to a novel pulsed laser deposition (PLD) approach for the definition of complex van der Waals heterostructures of 2D materials in MTJs. [6] This PLD growth approach unlocks the association in heterostructure of wide families of multifunctional 2D materials, including the most delicate ones. The different presented experiments unveil promising approaches for the quantum engineering of multifunctional 2D materials heterostructures for spintronics.

The current revolution in quantum technologies relies on coherently linking quantum objects like quantum bits (“qubits”). Coherent magnonic excitations of low-loss magnetic materials can wire together these qubits for sensing, memory, and computing. Coherent magnonics may reduce the size of superconducting qubits (which otherwise struggle with the large scale of microwave excitations) and may increase the size of spin-based qubit networks (which otherwise contend with the very short distances of dipolar or exchange interactions). Compared to photonic devices, these magnonic devices require minimal energy and space. However, efforts to exploit coherent magnonic systems for quantum information science will require a new understanding of the linewidths of low-loss magnonic materials shaped into novel structures and operating at dilution-refrigerator temperatures.

This lecture will introduce the fundamental requirements for practically linking quantum objects into large-scale coherent quantum systems as well as the advantages of coherent magnonics for next-generation quantum coherent systems (i.e., spin-entangling quantum gates [1]). Other critical challenges for quantum information science then will motivate the development of coherent magnonics for quantum transduction from “stationary” spin systems to “flying” magnons and for quantum memory [2]–[5]. Finally, the advantages of all-magnon quantum information technologies that rely on manipulating and encoding quantum information in superpositions of fixed magnon number states will highlight the potential of new magnetic materials, devices, and systems.

References

[1] “Opportunities for long-range magnon-mediated entanglement of spin qubits via on and off-resonant coupling,” PRX Quantum 2, 040314 (2021).

[2] “Predicted strong coupling of solid-state spins via a single magnon mode,” Mater. Quantum Technol. 1, 011001 (2021)

[3] “Strong field interactions between a nanomagnet and a photonic cavity,” PRL 104, 077202 (2010).

[4] “Optomagnonics in magnetic solids,” PRB 94, 060405(R) (2016).

[5] "Strong photon-magnon coupling using a lithographically defined organic ferrimagnet", arXiv:2212.04423.

Michael E. Flatté received the A.B. degree in physics from Harvard University, Cambridge, MA, USA, in 1988, and the Ph.D. degree in physics from the University of California at Santa Barbara, Santa Barbara, CA, USA, in 1992. He is a Professor at the Department of Physics and Astronomy, The University of Iowa (UI), Iowa City, IA, USA. After his post-doctoral work at the Institute for Theoretical Physics, University of California at Santa Barbara, and the Division of Applied Sciences, Harvard University, he joined the faculty at UI in 1995. He has over 270 publications and ten patents. He has an adjunct appointment as a Professor at the Department of Applied Physics, Eindhoven University of Technology, Eindhoven, The Netherlands. His research interests include optical and electrical control of spin dynamics in materials, novel spintronic devices, quantum sensors, and solid-state realizations of quantum computation. Dr. Flatté is a fellow of the American Association for the Advancement of Science and the American Physical Society.