Coherence time for spin defects at aqueous interfaces

Spin defects in two-dimensional (2D) materials are strong candidates for quantum information technology applications, in particular quantum sensing. Compared with thin films of 3D solids, 2D layers are free from unsaturated surface dangling bonds, which are detrimental to spin coherence. Interestingly, recent theoretical studies predicted a significant increase in the coherence time of defect-based qubits in monolayers, compared to their bulk counterparts [1,2]. In this work, we computed coherence times of spin defects in 2D materials in contact with water, geared towards understanding quantum sensors for biological systems. We consider graphene and hexagonal boron nitride (hBN) layers as test systems. We generated a structural model of the layer/water interface by performing classical molecular dynamics (MD) simulations of confined water between two graphene/hBN sheets using the LAMMPS code. We then used the MD trajectories to generate spin bath configurations for hypothetical spin defects in the solid layer, using the cluster correlation expansion method and the PyCCE code [3]. We considered an NV-like spin defect in graphene and a negatively charged boron-vacancy in hBN. In this talk we discuss how coherence time of defects in these two-dimensional materials in contact with water depend on magnetic field strength, nuclear spin concentration and isotopic composition.

[1] Ye, M. et al. npj Comput Mater 2019

[2] Onizhuk, M. et al. Appl. Phys. Lett. 2021.

[3] Onizhuk, M. et al. Adv. Theory Simul. 2021