*Published on 8 September 2021*

**Context**

A post-doctoral position is opened at the Interdisciplinary Research Institute of Grenoble (IRIG) of the CEA Grenoble (France) on the theory and modeling of silicon spin quantum bits (qubits). The selected candidate is expected to start at the beginning of year 2022, for up to two years.

Quantum information technologies on silicon have raised an increasing interest over the last few years

^{[1]}. Indeed, record coherence times have been achieved in^{28}Si samples^{[2]}; also, silicon benefits from the exceptional know-how developed for conventional micro-electronics, and is the natural platform for the co-integration of quantum bits (qubits) with the classical circuitry needed to drive them. Grenoble is pushing forward an original platform based on the “silicon-on-insulator” (SOI) technology. The information is stored in the spin of carrier(s) trapped in quantum dots, which are etched in a thin silicon film and are controlled by metal gates. This activity is carried out by a consortium bringing together three of the main laboratories of Grenoble, CEA/IRIG, CEA/LETI, and CNRS/Néel. On this SOI platform, Grenoble has for example demonstrated the first hole spin qubit

^{[3]}, and the electrical manipulation of a single electron spin^{[4].}Grenoble is now leading a European project on silicon spin qubits, named QLSI, in the context of the European quantum flagship.

**Left**- A SOI device with two “face to face” gates, each one controlling a quantum dot beneath. The information is encoded as a superposition of the up and down spin states of the carrier(s) trapped in these dots.

**Middle**- The same device as modeled in TB_Sim, with silicon in red, SiO_{2}in green, HfO_{2}in blue and the gates in gray.

**Right**- Iso-probability surfaces of the ground-state wave function under the leftmost gate; each red dot is a silicon atom at the surface of the channel (surface roughness is included in this simulation).

As many questions on spin qubits are still open, it is essential to support the experimental activity with state-of-the-art modeling. For that purpose, CEA is actively developing the “TB_Sim” code. TB_Sim is able to describe very realistic qubit structures down to the atomic scale when needed using atomistic tight-binding and multi-bands k.p models for the electronic structure of the materials. Using TB_Sim, CEA has recently investigated various aspects of the physics of spin qubits, in tight collaboration with the experimental groups in Grenoble and with the partners of CEA in Europe

^{[4-12}].**The aims of this postdoctoral position are to strengthen our understanding of spin qubits, and to progress in the design of efficient and reliable Si and Si/Ge spin qubit devices and arrays using a combination of analytical models and advanced numerical simulations with TB_Sim**

**. Topics of interest include:**

• Exchange interactions in 1D and 2D arrays of qubits and operation of multi-qubit gates,

• Sensitivity to noise (decoherence) and disorder (variability)...

The strengths and weaknesses of different proposals for spin qubit devices and arrays will, in particular, be assessed and compared. This work takes place in the context of the QLSI project and will be strongly coupled to the experimental activity in Grenoble and among the partners of CEA in Europe.

The candidate should send her/his CV to
Yann-Michel Niquet and
Michele Filippone, with a list of publications, a motivation letter with a summary of past accomplishments, and arrange for two recommendation letters.

**Required qualifications**

The candidate must have a PhD in Quantum, Condensed Matter or Solid-State Physics (or related topics).

**References**

^{[1] }

*Embracing the quantum limit in silicon computing*,

J. J. L. Morton, D. R. McCamey, M. A. Eriksson and S. A. Lyon,

Nature

**479**, 435 (2011).

^{[2] }

*Electron spin coherence exceeding seconds in high-purity silicon*,

A. M. Tyryshkin, S. Tojo, J. J. L. Morton, H. Riemann, N. V. Abrosimov, P. Becker, J.-J. Pohl, T. Schenkel, M. L. W. Thewalt, K. M. Itoh and S. A. Lyon,

Nature Materials

**11**, 143 (2012).

^{[3] }

*A CMOS silicon spin qubit*,

R. Maurand, X. Jehl, D. Kotekar-Patil, A. Corna, H. Bohuslavskyi, R. Laviéville, L. Hutin, S. Barraud, M. Vinet, M. Sanquer and S. de Franceschi,

Nature Communications

**7**, 13575 (2016).

^{[4] }

*Electrically driven electron spin resonance mediated by spin–valley–orbitc ouplingina silicon quantum dot*,

A. Corna, L. Bourdet, R. Maurand, A. Crippa, D. Kotekar-Patil, H. Bohuslavskyi, R. Laviéville, L. Hutin, S. Barraud, X. Jehl, M. Vinet, S. de Franceschi, Y.-M. Niquet and M. Sanquer,

npj Quantum Information

**4**, 6 (2018).

^{[5] }

*All-electrical manipulation of silicon spin qubits with tunable spin-valley mixing*,

L. Bourdet and Y.-M. Niquet,

Physical Review B

**97**, 155433 (2018).

^{[6] }

*Electrical spin driving by g-matrix modulation in spin-orbit qubits*,

A. Crippa, R. Maurand, L. Bourdet, D. Kotekar-Patil, A. Amisse, X. Jehl, M. Sanquer, R. Laviéville, H. Bohuslavskyi, L. Hutin, S. Barraud, M. Vinet, Y.-M. Niquet and S. de Franceschi,

Physical Review Letters

**120**, 137702 (2018).

^{[7] }

*Electrical manipulation of semiconductor spin qubits within theg-matrix formalism*,

B. Venitucci, L. Bourdet, D. Pouzada and Y.-M. Niquet,

Physical Review B

**98**, 155319 (2018).

^{[8] }

*Longitudinal and transverse electric field manipulation of hole spin-orbit qubits in one-dimensional channels*,

V. P. Michal, B. Venitucci and Y.-M. Niquet,

Physical Review B

**103**, 045305 (2021).^{[9] }*A Spin Quintet in a Silicon Double Quantum Dot: Spin Blockade and Relaxation*,T. Lundberg, J. Li, H. Hutin, B. Bertrand, D. J. Ibberson, C.-M. Lee, D. J. Niegemann, M. Urdampilleta, N. Stelmashenko, T. Meunier, Jason W. A. Robinson, L. Ibberson, M. Vinet, Y.-M. Niquet and M. F. Gonzalez-Zalba,

Physical Review X

**10**, 041010 (2020).^{[10] }*Hole-phonon interactions in quantum dots: Effects of phonon confinement and encapsulation materials on spin-orbit qubits*,J. Li, B. Venitucci and Y.-M. Niquet,

Phys. Rev. B

https://www.cea.fr/drf/irig/english/Pages/Departments/DPhy.aspx

http://www.researchgate.net/profile/Yann-Michel_Niquet

http://scholar.google.fr/citations?user=h02ymwoAAAAJ

**102**, 075415 (2020)^{[11] }

*Variability of electron and hole spin qubits due to interface roughness and charge traps*,

B. Martinez and Y.-M. Niquet,

arXiv: 2107.10902.

^{[12]}

*Wigner molecularization in asymmetric quantum dots*,

J.-C. Abadillo-Uriel, B. Martinez, M. Filippone and Y.-M. Niquet,

arXiv: 2107.11117.

**Additional information:**https://www.cea.fr/drf/irig/english/Pages/Departments/DPhy.aspx

http://www.researchgate.net/profile/Yann-Michel_Niquet

http://scholar.google.fr/citations?user=h02ymwoAAAAJ

The group responsible for spin qubits modeling now includes two permanent researchers (Y.-M. Niquet, M. Filippone), two PhD students and two postdocs.

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