​Project description:

Silicon & Germanium spin qubits have made outstanding progress in the past few years ^{[1, 2]}. In these devices, the elementary information is stored as a coherent superposition of the spin states of an electron or hole in a quantum dot. These spins can be manipulated electrically owing to spin-orbit coupling, and are entangled through exchange interactions, allowing for a variety of one- and two-qubit gates required for quantum computing and simulation. Grenoble is developing original spin qubit platforms on Si and Ge, and holds various records in spin lifetimes ^[3] and spin-photon interactions ^[4].
At IRIG/MEM, we support the progress of these advanced quantum technologies with state-of- the-art modelling ^{[3, 4]}. In particular, we are developing the TB_Sim code, able to describe very realistic qubit structures down to the atomic scale.
The role of Coulomb interactions in spin qubits remains poorly understood. Quantum dots with 3 to 5 electrons or holes are expected to screen noise & disorder better than singly-occupied ones; yet Coulomb interactions can dramatically reshape the spectrum and dynamics of the system (Wigner localization ^[5]...). The aim of this master training is, therefore, to model the effects of Coulomb interactions on spin qubits using “configuration interaction” methods for the many-body wave functions, in relation with ongoing experiments at IRIG.
This Master thesis may be followed by a PhD project on spin manipulation and entangle me nt in arrays of spin qubits. The Master/PhD candidate will have the opportunity to interact with a lively community of experimentalists working on spin qubits at CEA and CNRS.

Model for a Germanium spin qubit: A quantum dot is shaped in a Germanium quantum well (red) by the potentials applied to the C/L/R/T/B gates. The up and down spin states of the hole trapped in this quantum dot are split by the magnetic field B and used as a basis for coherent superpositions. The yellow shape is the isodensity surface that encloses 90% of the charge of the hole.


Masterstudent profile and qualifications:
The candidate must have a master in quantum or condensed matter physics/engineering, and a taste for numerical modeling. Excellent communication skills in English and the ability to work in a research team are required.

Scientific environment and workplace:
The successful candidate will join the “Laboratory of Atomistic Simulation (L_Sim)” of the “Modeling and Exploration of Materials (MEM)” service of the Interdisciplinary Research Institute of Grenoble (IRIG). The group modeling spin qubits comprises two permanent researchers, three PhD students and two postdocs. They work in very close collaboration with the members of the PHELIQS/LATEQS lab who measure spin qubits.

​​More information about MEM.

More information about the IRIG institute.