Silicon and Germanium spin qubits have made outstanding progress in the past few years [1-3]. In these devices, the elementary information is stored as a coherent superposition of the spin states of an electron or hole confined in a quantum dot embedded in a Si/SiO2 or Si/Ge heterostructure. 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 promoting original spin qubit platforms based on Si and Ge, and holds various records in spin lifetimes [4] and spin-photon interactions [5]. At CEA/IRIG, we support the progress of these quantum technologies with state-of-the-art modeling [4-6]. We are developing, in particular, the TB_Sim code, able to describe the electronic properties of very realistic qubit structures down to the atomic scale if needed.
One of the bottlenecks of quantum computing is the coupling between distant qubits in a quantum machine. Spin shuttling has emerged, therefore, as a resource for spin manipulation and transport [2, 3]. A carrier and its spin can indeed be moved (shuttled) coherently between neighboring quantum dots. This allows for the transport of quantum information over long ranges and for the coupling between distant spins in large arrays of qubits. Various designs for spin shuttlers and conveyors have already been proposed and demonstrated. They open the way for outstanding physics experiments and for innovative quantum architectures. The shuttling dynamics is however complex owing to the spin-orbit interactions that couple the motion of the carrier to its spin. This calls for a comprehensive understanding of these interactions and of their effects on the evolution and coherence of the spin.
The aim of this PhD is to model shuttling between Si/Ge spin qubits using a combination of analytical and numerical techniques (TB_Sim). The project will address spin manipulation, transport and entanglement in arrays of spin qubits, as well as the response to noise and disorder (decoherence). The PhD candidate will have the opportunity to join a leading modeling group in Europe and to interact with a lively community of experimentalists working on spin qubits at CEA and CNRS. This PhD is expected to start in September/October 2025.
To apply, send CV, letter of motivation, academic record and the e-mails of two contacts for references to Yann-Michel Niquet (yniquet@cea.fr).
The candidates are expected to have a master degree in condensed matter or quantum physics related areas, and shall have a taste for numerical modeling.
More information about the laboratory:
https://www.cea.fr/drf/irig/english/Pages/Departments/DPhy.aspx
https://scholar.google.fr/citations?user=h02ymwoAAAAJ
More about Grenoble and its surroundings: http://www.isere-tourism.com/
References:
[1] Universal control of a six-qubit quantum processor in silicon, S. G. J. Philips et al., Nature 609, 919 (2022).
[2] Coherent spin qubit shuttling through germanium quantum dots, F. van Riggelen-Doelman et al., Nature Comm. 15, 5716 (2024).
[3] Blueprint of a scalable spin qubit shuttle device for coherent mid-range qubit transfer in disordered Si/SiGe/SiO2, V . Langrock et al., PRX Quantum 4, 020305 (2023).
[4] A single hole spin with enhanced coherence in natural silicon, N. Piot, …, Y. M. Niquet et al., Nature Nano 17, 1072 (2022).
[5] Strong coupling between a photon and a hole spin in silicon, C. X. Yu, …, Y. M. Niquet et al., Nature Nano 18, 741 (2023).
[6] Hole-spin driving by strain-induced spin-orbit interactions, J. C. Abadillo-Uriel, E. A. Rodriguez-Mena, B. Martinez, Y. M. Niquet, Physical Review Letters 131, 097002 (2023).
