Spin relaxation in a silicon-based quantum dot qubit*

Electron spins in silicon-based quantum dots show much promise as qubits in future large-scale quantum computation platforms, and simple quantum algorithms have been already implemented. However, an important question remains unanswered, of whether this platform can operate in "hot" conditions, at the temperatures higher than 1 K. Besides fundamental interest, the operating temperature may severely limit the scaling capabilities, because of heat dissipation from the classical control electronics needed for operation of a many-qubit quantum processor.

In this talk we will discuss the relaxation mechanisms that govern the lifetime of a spin in the silicon quantum dot. We will theoretcially analyze the spin-orbit processes, including the influence of the electric charge noise and the spin-phonon coupling, that may limit the spin lifetime T1 at different magnetic fields and temperatures. We will present experimental data which, in agreement with the theoretical analysis, show that even at 1 K the spin lifetime does not limit operation of the spin qubit [1]. We will also discuss the possible ways of prolonging the spin lifetime by increasing the valley splitting and working at lower magnetic fields, with the aim to reach stable operation at 4 K.

[1] L. Petit, J. M. Boter, H. G. J. Eeninck et al, Phys. Rev. Lett. 121, 076801 (2018).