Robust control of entanglement in a Nitrogen-vacancy centre coupled to a Carbon-13 nuclear spin in diamond

TL;DR

This paper compares control schemes for entangling electronic and nuclear spins in a nitrogen-vacancy center in diamond, demonstrating that numerically-optimized pulses offer superior robustness and speed over traditional methods.

Contribution

It introduces the use of gradient ascent pulse engineering (GRAPE) for robust entangling gates in NV centers, outperforming composite and sequential pulses.

Findings

Numerically-optimized GRAPE pulses are more robust against systematic errors.

GRAPE pulses can be implemented faster than composite pulses.

Optimized pulses improve entanglement fidelity in NV centers.

Abstract

We address a problem of generating a robust entangling gate between electronic and nuclear spins in the system of a single nitrogen-vacany centre coupled to a nearest Carbon-13 atom in diamond against certain types of systematic errors such as pulse-length and off-resonance errors. We analyse the robustness of various control schemes: sequential pulses, composite pulses and numerically-optimised pulses. We find that numerically-optimised pulses, produced by the gradient ascent pulse engineering algorithm (GRAPE), are more robust than the composite pulses and the sequential pulses. The optimised pulses can also be implemented in a faster time than the composite pulses.