Decoherence of two entangled spin qubits coupled to an interacting sparse nuclear spin bath - Application to nitrogen vacancy centers
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2018-10-05 |
| Journal | Physical review. B./Physical review. B |
| Authors | Damian Kwiatkowski, Ĺukasz CywiĹski |
| Institutions | Polish Academy of Sciences, Institute of Physics |
| Citations | 31 |
Abstract
Section titled âAbstractâWe consider pure dephasing of Bell states of electron spin qubits interacting\nwith a sparse bath of nuclear spins. Using the newly developed two-qubit\ngeneralization of cluster correlation expansion method, we calculate the spin\necho decay of $|\Psi\rangle$ and $|\Phi\rangle$ states for various interqubit\ndistances. Comparing the results with calculations in which dephasing of each\nqubit is treated independently, we identify signatures of influence of common\npart of the bath on the two qubits. At large interqubit distances, this common\npart consists of many nuclei weakly coupled to both qubits, so that decoherence\ncaused by it can be modeled by considering multiple uncorrelated sources of\nnoise (clusters of nuclei), each of them weakly affecting the qubits.\nConsequently, the resulting genuinely two-qubit contribution to decoherence can\nbe described as being caused by classical Gaussian noise. On the other hand,\nfor small interqubit distances the common part of the environment contains\nclusters of spins that are strongly coupled to both qubits, and their\ncontribution to two-qubit dephasing has visibly non-Gaussian character. We show\nthat one van easily obtain information about non-Gaussianity of environmental\nnoise affecting the qubits from the comparison of dephasing of $|\Psi\rangle$\nand $|\Phi\rangle$ Bell states. Numerical results are obtained for two nitrogen\nvacancy centers interacting with a bath of $^{13}$C nuclei of natural\nconcentration, for which we obtain that Gaussian description of correlated part\nof environmental noise starts to hold for centers separated by about 3 nm.\n