Quantum sensing of photonic spin density using a single spin qubit

Optically induced static magnetic field in ensemble of nitrogen-vacancy centers in diamond

“…For example, magneto-optical Barnett effect uses circularly polarized light to switch magnetization in magnetic thin films using ultrafast optical pulses [1,2], valley-selective optical pumping can induce nonreciprocity in transition metal dichalcogenides [3], while structured light can be used to induce a magnetic field by shaping optically induced currents [4]. Recently it was shown that a single nitrogen-vacancy (NV) center can probe an effective static magnetic field induced by the photonic spin density (PSD) of an optical beam [5]. PSD is the spatial distribution of the degree of circular polarization of an optical field at the nanoscale.…”

“…PSD is the spatial distribution of the degree of circular polarization of an optical field at the nanoscale. While most optically induced magnetic fields rely on absorption of light and are incoherent interactions, the optically induced magnetic field probed by a single NV center is non-absorbing and coherently interacts with the NV center even at room temperature [5].…”

“…The NV center in diamond has emerged as a singlespin quantum magnetometer for probing condensed matter phenomena [6][7][8][9]. The recent work by Kalhor et al demonstrating the optically induced static magnetic field for the NV center shows that this quantum sensor can also be used to probe properties of light fields at the nanoscale [5]. This work uses a single NV center on an atomic force microscopy (AFM) tip to measure the optically induced effective static magnetic field.…”

“…This work uses a single NV center on an atomic force microscopy (AFM) tip to measure the optically induced effective static magnetic field. While reference [5] focuses on probing the photonic spin density (PSD), the demonstrated induced magnetic field can also be used for coherent control of NV center qubits. This coherent control of spin qubits is arguably a consequential application for the PSD based phenomenon.…”

“…The interaction of the beam with NV centers induces a rotation in the spin vector of the NV centers on the Bloch sphere. This rotation is proportional to the PSD of the beam and we define an effective static magnetic field to describe the strength of this interaction (see [5]). The NV centers are randomly scattered in the bulk of a single crystalline diamond, with their four different orientations determined by the (100) growth plane.…”