Quantum Decoherence in Reduced Dimensions

The electronic spin states of certain point defects in solid state materials have been shown to be promising quantum bits (qubit) for quantum information processes. Long spin coherence time is an important criterion to meet, in order to realize a qubit. In the presence of an external magnetic field and at low temperatures, decoherence originates mainly from the temporally fluctuating random magnetic field induced by nuclear spin flip-flops. This process can be theoretically described by a spin Hamiltonian and approximately solved by a cluster-correlation expansion (CCE) method [1]. Recently, single-photo emitters have been discovered in several reduced dimensional systems, such as 2D hexagonal-BN. In this work, we used the CCE method to study the decoherence of a electron spin immersed in a nuclear spin bath as a function of dimensionality. We considered 3D bulk materials, thin films, and 2D materials. Our results shed light on the importance of dimensionality in determining the spin decoherence dynamics of spin defects and provide predictions about promising solid-state qubits in low dimensional systems.
[1] Yang and Liu, Phys. Rev. B 79, 115320 (2009)