**Project QuantEra Si-QiBus entitled**

*“Long-range quantum bus for electron spin qubits in silicon” (2018-2021)
*

This QuantEra project is being carried out by the European Si-QuBus consortium that consists of six partners working tightly together in order to realize a QuBus in silicon. The six principal investigators and groups are:

- Coordinator: Lars Schreiber (RWTH Aachen, University, DE)
- Lieven Vandersypen (Delft University of Technology, NL)
- Tristan Meunier (INSTITUT NEEL – CNRS, FR)
- Sylvain Barraud (Commissariat à l’Energie Atomique et aux Energies Alternatives, FR)
- Łukasz Cywiński (Institute of Physics, Polish Academy of Sciences, PL)
- David DiVincenzo (Forschungszentrum Jülich, DE)

**The Objective**

The goal of the project is to demonstrate long-distance transfer of electron spin qubit in a silicon nanostructure. We want to coherently transfer an electron in a superposition of its spin states along a chain of gate-defined quantum dots. Achiecing this objective will allow for significant progress in scaling of quantum-dot based spin qubits in semiconductor architecture.

**Main results obtained so far with the involvement of the Warsaw group (for all the results see the consortium website)
**

1) Development of theoretical description of adiabatic electron electron transfer between two quantum dots in presence of 1/f charge noise [1].

2)Theoretical assistance in elucidation of dominant sources of decoherence of a silicon quantum dot based spin qubits controlled by a nearby nanomagnet [2].

**Publications**

[4] V. Langrock, J. A. Krzywda, N. Focke, I. Seidler, L. R. Schreiber, and and Ł. Cywiński

*Blueprint of a scalable spin qubit shuttle device for coherent mid-range qubit transfer in disordered Si/SiGe/SiO2*

arXiv:2202.11793

[3] J. A. Krzywda and Ł. Cywiński

*Interplay of charge noise and coupling to phonons in adiabatic electron transfer between quantum dots*

Phys. Rev. B **104**, 075439 (2021)

arXiv:2104.07581

[2] T. Struck, A. Hollmann, F. Schauer, O. Fedorets, A. Schmidbauer, K. Sawano,

H. Riemann, N. V. Abrosimov, Ł. Cywinski, D. Bougeard, and L. R. Schreiber

*Low-frequency spin qubit detuning noise in highly purified 28Si/SiGe*

npj Quantum Information **6**, 40 (2020)

arXiv:1909.11397

[1] J. A. Krzywda and Ł. Cywiński

*Adiabatic electron charge transfer between two quantum dots in presence of 1/ f noise*

Phys. Rev. B **101**, 035303 (2020)

arXiv:1909.11780