Omnidirectional Magnetic Field Sensing using Spin Qubits in Boron Nitride Nanotubes

Saakshi Dikshit
Purdue University, West Lafayette, Indiana, USA _______________________________________

Quantum sensing has become an irreplaceable technological tool in recent times to study various important physical phenomenon and quantities. Solid state spin defects in 2-D and 3-D systems such as the boron vacancy in hexagonal Boron Nitride (h-BN) and NV center in diamond have proven to be excellent quantum sensors. However, optically addressable spin defects in 1-D systems have remained elusive till now. In this work, we present the observation of optically addressable single spin defects in a 1-D material, Boron Nitride Nanotubes. We determine the spin multiplicity of these defects to be S=1/2, indicating a lack of intrinsic quantization axis and thus enabling omnidirectional magnetic field sensing. We use these spin defects to study the anisotropic magnetization in FGT flakes in two orthogonal directions, which is challenging for spin qubits with an intrinsic quantization axis. Finally, we develop a transfer method to deterministically attach a single BNNT with spin defects onto an AFM cantilever and use the BNNT as a scanning probe to generate a 2D magnetic map of Nickel patterns on a gold waveguide.

Email: sdikshi@purdue.edu