Spin-valley protected Kramers pair in bilayer graphene.

ABSTRACT: The intrinsic valley degree of freedom makes bilayer graphene (BLG) a unique platform for semiconductor qubits. The single-carrier quantum dot (QD) ground state exhibits a twofold degeneracy, where the two states that constitute a Kramers pair have opposite spin and valley quantum numbers. Because of the valley-dependent Berry curvature, an out-of-plane magnetic field breaks the time-reversal symmetry of this ground state and a qubit can be encoded in the spin-valley subspace. The Kramers states are protected against known spin- and valley-mixing mechanisms because mixing requires a simultaneous change of the two quantum numbers. Here, we fabricate a tunable QD device in Bernal BLG and measure a spin-valley relaxation time for the Kramers states of 38 s at 30 mK, which is two orders of mag

SUBMITTER: Denisov AO 

PROVIDER: S-EPMC12015173 | biostudies-literature | 2025 Apr

REPOSITORIES: biostudies-literature