A post-doctoral position is opened at the Institute for Nanosciences and Cryogenics (INAC) of  the CEA Grenoble (France) for up to two years, on the theory and modeling of silicon-on-insulator quantum bits.

Quantum information technologies on silicon have raised an increasing interest over the last five  years [1]. Indeed, record coherence times have been achieved in 28Si samples [2]; also, silicon benefits fromthe 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.

CEA Grenoble/LETI is pushing forward an original platform based on the “silicon-on-insulator ” (SO I  )t ec hnology. The information is stored in the spin of carrier(s) trapped in quantum dots, which areetched in a thin silicon film and are controlled by metal gates. SOI has many assets: the patterning ofthe thin film can produce smaller, hence more scalable qubits; also, the use of the silicon substratebeneath as a back gate provides extra control over the qubits. On this SOI platform, CEA hasdemonstrated the first hole spin qubit [3], and has achieved the electrical manipulation of a singleelectron spin [4] using the weak, intrinsic spin-orbit coupling in the conduction band of silicon.


(Left) A SOI device with two “face to face” gates, each one controlling a quantum dot beneath. The information is encoded as  asuperposition 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, SiO2 in green, HfO2 in blue and the gates in gray. (Right) Iso-probability surfaces of the g round-statewave 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).

Many aspects of the physics of silicon spin qubits are still poorly understood. It is, therefore,  essential to complement the experimental activity with state-of-the-art modeling. For that purpose, CEA/INAC is actively developing the “TB_Sim” code. TB_Sim relies on atomistic tight-binding and multi-bandsk.p descriptions of the electronic structure of materials and includes, in particular, a time-dependent configuration interaction solver for the dynamics of interacting qubits. Using TB_Sim, CEA INAC has
recently investigated various aspects of the physics of silicon qubits , in tight collaboration with theexperimental team in Grenoble and the partners of CEA in Europe [4-8].

The aims of this post-doctoral position are, in particular:
• To model spin manipulation and readout in SOI qubits in  order to get a better understandingof the physics of these devices and optimize their design.
• To model decoherence and relaxation at the atomistic scale.

This work will be strongly coupled to the experimental activity in Grenoble. CEA is indeed at the heart of a quantum silicon eco-system in Grenoble, bringing together CEA/LETI (fabrication), CEA/INAC and CNRS/Néel (characterization and modeling) around the development of SOI qubits. The candidate will, therefore, have access to experimental data on state-of-the-art devices.

The candidate should send her/his CV to Yann-Michel Niquet (yniquet@cea.fr), with a list of publications, a motivation letter with a summary of past accomplishments, and contact details of two persons for references (or recommendation letters).
[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–orbit coupling in a 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,
Submitted to Physical Review B (arXiv: 1802.04693).
[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] Linear hyperfine tuning of donor spins in silicon using hydrostatic strains,
J. Mansir, P. Conti, Z. Zeng, J. J. Pla, P. Bertet, M. W. Swift, C. G. Van de Walle, M. L. W.
Thewalt, B. Sklenard, Y.-M. Niquet and J. J. L. Morton,
Accepted for publication in Physical Review Letters (arXiv: 1710.00723).
[8] Strain-induced spin resonance shifts in silicon devices,
J. J. Pla, A. Bienfait, G. Pica, J. Mansir, F. A. Mohiyaddin, Z. Zeng, Y.-M. Niquet, A. Morello, T. Schenkel, J. J. L. Morton and P. Bertet,
Accepted for publication in Physical Review Applied (arXiv: 1608.07346).

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