Pulsed-gate spectroscopy on single-electron quantum dots in bilayer graphene

Thanks to its weak spin-orbit coupling and low nuclear spin density bilayer graphene (BLG) promises long spin relaxation and coherence times, making this material a potentially interesting platform for spin-based solid state quantum computation [1]. Although the electrostatic confinement of single electrons in BLG quantum dot (QD) devices has been demonstrated and their single particle spectrum has been studied in detail [2,3], their relaxation dynamics remain so far mostly unexplored [4].

Here, we report on measurements of the spin relaxation times (T1) of single-electron spin states in a BLG QD. Using pulsed-gate spectroscopy, we extract T1 times exceeding 200μs at out-of-plane magnetic fields below 2T. The measured values for T1 show a strong dependence on the spin splitting and increase by about two orders of magnitude when decreasing the magnetic field from 2-3 T, suggesting that T1 could be significantly larger at low magnetic fields.

[1] B. Trauzettel et al., Nat. Phys. 3, 192 (2007).

[2] M. Eich et al., Phys. Rev. X 8, 031023 (2018).

[3] A. Kurzmann et al., Phys. Rev. Lett. 123, 026803 (2019).

[4] L. Banszerus et al., Phys. Rev. B 103, L081404 (2021).