CEA
CNRS
Univ. Paris-Saclay

Service de Physique de l'Etat Condensé

SPEC PhD subjects

7 sujets IRAMIS//SPEC

Dernière mise à jour :


• Mesoscopic physics

• Soft matter and complex fluids

• Solid state physics, surfaces and interfaces

 

Fermionic-bosonic qubit

SL-DRF-24-0391

Location :

Service de Physique de l’Etat Condensé (SPEC)

Groupe Quantronique (GQ)

Saclay

Contact :

Hugues POTHIER

Starting date : 01-10-2024

Contact :

Hugues POTHIER
CEA - DRF/IRAMIS/SPEC/GQ

01 69 08 55 29

Thesis supervisor :

Hugues POTHIER
CEA - DRF/IRAMIS/SPEC/GQ

01 69 08 55 29

Personal web page : https://iramis.cea.fr/Pisp/hugues.pothier/

Laboratory link : https://iramis.cea.fr/spec/GQ/

One of the most promising architectures in large-scale quantum information processing is the one based on superconducting electrodynamic (bosonic) qubits. They rely on an elementary device: the Josephson tunnel junction, a tunnel barrier between two superconducting leads, which exhibit nonlinear and non-dissipative behavior. Josephson tunnel junctions are only an example of superconducting weak links, among which are also atomic contacts and semiconducting nanowire weak links. In these other examples, localized, fermionic states, known as Andreev levels, can be addressed. We recently performed their spectroscopy [1-4] and quantum manipulation [5,6].

Here we propose to design, fabricate and measure new hybrid qubits that combine bosonic and fermionic degrees of freedom in the quest to realize more robust quantum states.

We are looking for a strongly motivated student having a good understanding of quantum physics. She/he will be integrated in an active research group on quantum electronics and get acquainted with advanced concepts of quantum mechanics and superconductivity. He/she will also learn several experimental techniques: low temperatures, low-noise and microwave measurements, and nanofabrication.



[1] L. Bretheau, Ç. Ö. Girit , H. Pothier , D. Esteve , and C. Urbina, “Exciting Andreev pairs in a superconducting atomic contact” Nature 499, 312 (2013). arXiv:1305.4091
[2] L. Tosi, C. Metzger, M. F. Goffman, C. Urbina, H. Pothier, Sunghun Park, A. Levy Yeyati, J. Nygård, P. Krogstrup, “Spin-Orbit Splitting of Andreev States Revealed by Microwave Spectroscopy”, Phys. Rev. X 9, 011010 (2019).
[3] C. Metzger, Sunghun Park, L. Tosi, C. Janvier, A. A. Reynoso, M. F. Goffman, C. Urbina, A. Levy Yeyati, H. Pothier, “Circuit-QED with phase-biased Josephson weak links”, Phys. Rev. Research 3, 013036 (2021).
[4] F. J. Matute Cañadas, C. Metzger, Sunghun Park, L. Tosi, P. Krogstrup, J. Nygård, M. F. Goffman, C. Urbina, H. Pothier, A. Levy Yeyati, “Signatures of interactions in the Andreev spectrum of nanowire Josephson junctions”, arXiv:2112.05625
[5] C. Janvier et al., “Coherent manipulation of Andreev states in superconducting atomic contacts” Science 349, 1199 (2015), arXiv:1509.03961
[6] C. Meztger, “Spin & charge effects in Andreev Bound States”, PhD thesis (2022)
Thermal transport in non-abelian quantum hall states of graphene

SL-DRF-24-0305

Research field : Mesoscopic physics
Location :

Service de Physique de l’Etat Condensé (SPEC)

Groupe Nano-Electronique (GNE)

Saclay

Contact :

François PARMENTIER

Starting date : 01-10-2024

Contact :

François PARMENTIER
CNRS - DRF/IRAMIS/SPEC/GNE

+33169087311

Thesis supervisor :

François PARMENTIER
CNRS - DRF/IRAMIS/SPEC/GNE

+33169087311

Personal web page : https://iramis.cea.fr/Phocea/Membres/Annuaire/index.php?uid=fparment

Laboratory link : https://iramis.cea.fr/SPEC/GNE/

More : https://nanoelectronicsgroup.com

Even-denominator states of the fractional quantum Hall effect (e.g. ??=5/2) are expected to host excitations that have non-abelian anyonic statistics, making them promising candidates for the realization of topological quantum computing [1]. While the demonstration of these non-abelian statistics has long been an extremely challenging endeavor, recent experiments in GaAs semiconductor heterostructures have shown that the edge thermal conductance of the ??=??/?? state is quantized in half-integer values of the thermal conductance quantum [2,3]. This half-integer quantization is known to be an universal signature of non-abelian statistics, including of Majorana fermions [4]. However, many of the suspected candidates for the ground state of ??=5/2 have complex edge structures exhibiting counterpropagating neutral modes, which can modify the edge thermal conductance and give them non-integer values similar to that of a non-abelian edge. A very recent experiment [3] has circumvented the issue by finding a way to separate the contributions of the different channels at the edge, confirming the existence of a non-abelian channel with half-integer quantized electrical and thermal conductance. The next obvious interrogation is whether this result is truly universal: does it hold for different material, and different even-denominator states?

In this project, we propose to address these questions by performing heat transport measurements in fractional quantum Hall states in bilayer graphene. Bernal-stacked bilayer graphene (BLG) has recently shown to host a large variety of robust even-denominator fractional quantum Hall states [5-8], both hole- and electron-type. This provides an excellent test-bed on which to probe the thermal conductance, as these fractions are expected to be described by different (possibly non-abelian) ground states; furthermore, the ability to apply electric displacement fields allows a further degree of control over the even-denominator states, which can be investigated in terms of heat transport.

This experimental project relies on ultra-low temperature, high magnetic field thermal transport [9] based on high sensitivity-sensitivity electrical measurements. We are looking for highly motivated candidates whoe are interested in all aspects of the project, both experimental (sample fabrication, low noise measurements, cryogenics) and theoretical.

[1] Nayak, et al., RMP 80, 1083 (2008) [2] Banerjee, et al., Nature 559, 205 (2018)
[3] Dutta, et al., Science 377, 1198 (2022) [4] Kasahara, et al., Nature 559, 227 (2018)
[5] Ki, et al., Nano Letters 14, 2135 (2014) [6] Li, et al., Science 358, 648 (2017)
[7] Zibrov, et al., Nature 549, 360 (2017) [8] Huang, et al., PRX 12, 031019 (2022)
[9] Le Breton, …, & Parmentier, PRL 129, 116803 (2022)
Thermoelectric energy conversion in nanofluids for hybrid solar heat collector

SL-DRF-24-0358

Research field : Soft matter and complex fluids
Location :

Service de Physique de l’Etat Condensé (SPEC)

Systèmes Physiques Hors-équilibre, hYdrodynamique, éNergie et compleXes (SPHYNX)

Saclay

Contact :

Sawako NAKAMAE

Starting date : 01-10-2021

Contact :

Sawako NAKAMAE
CEA - DRF/IRAMIS/SPEC/SPHYNX

0169087538

Thesis supervisor :

Sawako NAKAMAE
CEA - DRF/IRAMIS/SPEC/SPHYNX

0169087538

Personal web page : https://iramis.cea.fr/spec/Pisp/sawako.nakamae/

Laboratory link : http://iramis.cea.fr/spec/SPHYNX/

More : https://www.magenta-h2020.eu

Thermoelectric (TE) materials that are capable of converting heat into electricity have been considered as one possible solution to recover the low-grade waste-heat (from industrial waste-stream, motor engines, household electronic appliances or body-heat).

At SPHYNX, we explore thermoelectric effects in an entirely different class of materials, namely, complex fluids containing electrically charged nanoparticles that serve as both heat and electricity carriers. Unlike in solid materials, there are several inter-dependent TE effects taking place in liquids, resulting in Se values that are generally an order of magnitude larger that the semiconductor counterparts. Furthermore, these fluids are composed of Earth-abundant raw materials, making them attractive for future TE-materials that are low-cost and environmentally friendly. While the precise origins of high Seebeck coefficients in these fluids are still debated, our recent results indicate the decisive role played by the physico-chemical nature of particle-liquid interface.

The goal of the PhD project is two-fold :
- First, we will investigate the underlying laws of thermodynamic mechanisms behind the thermoelectric potential and power generation and other associated phenomena in nanofluids. More specifically, we are interested in how the particles' Eastman entropy of transfer is produced under the influence of thermal, electrical and concentration gradients. The results will be compared to their thermos-diffusive and optical abosrption properties to be obtained through research collaborations.
- Second, the project aims to test the promising nanofluids in the proof-of-concept hybrid solar-collector devices currently developed within the group to demonstrate the co-generation capability of heat and electricity. The hybrid device optimization is also within the project's scope

The proposed research project is primarily experimental, involving thermos-electrical, thermal and electrochemical measurements; implementation of automated data acquisition system and analysis of the resulting data obtained. The notions of thermodynamics, fluid physics and engineering (device) physics, as well as hands-on knowledge of experimental device manipulation are needed. Basic knowledge of optics and electrochemistry is a plus. For motivated students, numerical simulations using commercial CFD software, as well as the optical absorption measurements at the partner lab (LNO/CNR, Florence, Italy) can also be envisaged.
Experimental study of boundary layers in turbulent convection by Diffusive Waves Spectroscopy

SL-DRF-24-0355

Research field : Soft matter and complex fluids
Location :

Service de Physique de l’Etat Condensé (SPEC)

Systèmes Physiques Hors-équilibre, hYdrodynamique, éNergie et compleXes (SPHYNX)

Saclay

Contact :

Sébastien AUMAITRE

Starting date : 01-10-2024

Contact :

Sébastien AUMAITRE
CEA - DRF/IRAMIS/SPEC/SPHYNX


Thesis supervisor :

Sébastien AUMAITRE
CEA - DRF/IRAMIS/SPEC/SPHYNX


Personal web page : https://iramis.cea.fr/Pisp/sebastien.aumaitre/

Laboratory link : https://iramis.cea.fr/spec/sphynx/

The aim of this thesis is to carry out the first experimental measurement of the energy dissipated in the boundary layers during turbulent convection in the Rayleigh-Bénard configuration. Indeed, some theories assert that this quantity controls the heat flux transported from the hot wall to the cold wall, while the efficiency of turbulent transport in convection is the subject of debate. Yet the properties of turbulent transport are essential to understanding the dynamics of climate and many astrophysical objects.

To estimate the energy dissipated, we need to be able to measure the norm of the velocity gradient. This quantity is difficult to access with conventional anemometry techniques, which measure velocity fields with limited resolution. These gradients are also expensive to obtain numerically over long time scales. But we have developed a technique for directly measuring the norm of velocity gradients using Multiple Scattering Spectroscopy. This will enable us to measure dissipative structures and the rate of energy dissipation in boundary layers.
Dielectric response of a liquid far-from-equilibrium

SL-DRF-24-0279

Research field : Soft matter and complex fluids
Location :

Service de Physique de l’Etat Condensé (SPEC)

Systèmes Physiques Hors-équilibre, hYdrodynamique, éNergie et compleXes (SPHYNX)

Saclay

Contact :

Marceau HENOT

François LADIEU

Starting date : 01-09-2024

Contact :

Marceau HENOT
CEA - DRF/IRAMIS/SPEC/SPHYNX


Thesis supervisor :

François LADIEU
CEA - DRF/IRAMIS

01 69 08 72 49

Personal web page : https://iramis.cea.fr/Pisp/marceau.henot/

Laboratory link : https://iramis.cea.fr/spec/SPHYNX/

Materials in the glassy state are of great practical interest and can be found in many applications: silica glass as a construction or transport material, plastics which are generally at least partially glassy, or glassy metal alloys for advanced applications. However, the physical properties of these materials (e.g. the strength of a telephone screen) depend on the heat treatment they receive during their formation, and more specifically on the rate of cooling from the liquid state. While industrial glass manufacturing processes are obviously well mastered, the non-equilibrium thermodynamic nature of these systems makes it particularly difficult to investigate the physical mechanisms at work theoretically and numerically. This calls for an experimental approach aimed at probing these fundamental mechanisms.

The aim of this PhD thesis is to study experimentally the very non-equilibrium response of polar liquids, using a device recently developed in the laboratory which enables us to apply a very rapid temperature change to a liquid and follow its re-equilibration dynamics. Measurements of linear response should reveal more about the physical mechanisms governing equilibration, while non-linear measurements will provide information about the cooperative nature of structural rearrangements.
Multi-level functionality in ferroelectric, hafnia-based thin films for edge logic and memory

SL-DRF-24-0639

Research field : Solid state physics, surfaces and interfaces
Location :

Service de Physique de l’Etat Condensé (SPEC)

Laboratoire d’Etude des NanoStructures et Imagerie de Surface (LENSIS)

Saclay

Contact :

NiCK BARRETT

Starting date : 01-10-2024

Contact :

NiCK BARRETT
CEA - DRF/IRAMIS/SPEC/LENSIS

0169083272

Thesis supervisor :

NiCK BARRETT
CEA - DRF/IRAMIS/SPEC/LENSIS

0169083272

Personal web page : https://iramis.cea.fr/Pisp/87/nick.barrett.html

Laboratory link : https://www.lensislab.com/

More : https://www.lensislab.com/projects

The numerical transition to a more attractive, agile and sustainable economy relies on research on future digital technologies.

Thanks to its non-volatility, CMOS compatibility, scaling and 3D integration potential, emerging memory and logic technology based on ferroelectric hafnia represents a revolution in terms of possible applications. For example, with respect to Flash, resistive or phase change memories, ferroelectric memories are intrinsically low power by several orders of magnitude.

The device at the heart of the project is the FeFET-2. It consists of a ferroelectric capacitor (FeCAP) wired to the gate of a standard CMOS transistor. These devices have excellent endurance, retention and power rating together with the plasticity required for neuromorphic applications in artificial intelligence.

The thesis will use advanced characterization techniques, in particular photoemission spectroscopy and microscopy to establish the links between material properties and the electrical performance of the FeCAPs.

Operando experiments as a function of number of cycles, pulse amplitude and duration will allow exploring correlations between the kinetics of the material properties and the electrical response of the devices.

The thesis work will be carried out in close collaboration with NaMLab (Dresden) and the CEA LETI (Grenoble).
Novel oxynitride based artificial multiferroic oxynitride thin films

SL-DRF-24-0474

Research field : Solid state physics, surfaces and interfaces
Location :

Service de Physique de l’Etat Condensé (SPEC)

Laboratoire Nano-Magnétisme et Oxydes (LNO)

Saclay

Contact :

Antoine BARBIER

Starting date : 01-10-2024

Contact :

Antoine BARBIER
CEA - DRF/IRAMIS/SPEC/LNO

01.69.08.39.23

Thesis supervisor :

Antoine BARBIER
CEA - DRF/IRAMIS/SPEC/LNO

01.69.08.39.23

Personal web page : https://iramis.cea.fr/Pisp/137/antoine.barbier.html

Laboratory link : https://iramis.cea.fr/spec/LNO/

N-doped oxides and/or oxinitrides constitute a booming class of compounds with a broad spectrum of useable properties and in particular for novel technologies of carbon-free energy production and multifunctional sensors. In this research field the search for new materials is particularly desirable because of unsatisfactory properties of current materials. The insertion of nitrogen in the crystal lattice of an oxide semiconductor allows in principle to modulate its electronic structure and transport properties enabling new functionalities. The production of corresponding single crystalline thin films is highly challenging. In this thesis work, single crystalline oxynitride heterostructures will be grown by atomic plasma-assisted molecular beam epitaxy. The heterostructure will combine two N doped layers: a N doped BaTiO3 will provide ferroelectricity and a heavily doped ferrimagnetic ferrite whose magnetic properties can be modulated using N doping to obtain new artificial multiferroic materials better suited to applications. The resulting structures will be investigated with respect to their ferroelectric and magnetic characteristics as well as their magnetoelectric coupling, as a function of the N doping. These observations will be correlated with a detailed understanding of crystalline and electronic structures.

The student will acquire skills in ultra-high vacuum techniques, molecular beam epitaxy, ferroelectric and magnetic characterizations as well as in state-of-the-art synchrotron radiation techniques.

 

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