Light modulation by a magnetic resonance in a paramagnet

Sergey G. Rautian, A. G. Rudavets

Mark Hughes, Heqing Li, Nafsika Theodoropoulou +1 more

Abstract Er implanted Si is a candidate for quantum and photonic applications; however, several different Er centres are generated, and their symmetry, energy level structure, magnetic and optical properties, and mutual interactions have been poorly understood, which has been a major barrier to the development of these applications. Optically modulated magnetic resonance (OMMR) gives a spectrum of the modulation of an electron paramagnetic resonance (EPR) signal by a tuneable optical field. Our OMMR spectrum of Er implanted Si agrees with three independent measurements, showing that we have made the first measurement of the crystal field splitting of the 4I13/2 manifold of Er implanted Si, and allows us to revise the crystal field splitting of the 4I15/2 manifold. This splitting originates from a photoluminescence (PL) active O coordinated Er centre with orthorhombic C2v symmetry, which neighbours an EPR active O coordinated Er centre with monoclinic C1h symmetry. This pair of centres could form the basis of a controlled NOT (CNOT) gate.

Pranawa C. Deshmukh, Sudha Krishnaswamy

Zhehua Huang, Zhengze Zhao, Fei Kong +7 more

The nitrogen-vacancy (NV) center can serve as a magnetic sensor for electron paramagnetic resonance (EPR) measurements. Benefiting from its atomic size, the diamond chip can integrate a tremendous amount of NV centers to improve the magnetic-field sensitivity. However, EPR spectroscopy using NV ensembles is less efficient due to inhomogeneities in both sensors and targets. Spectral line broadening induced by ensemble averaging is even detrimental to spectroscopy. Here we show a kind of cross-relaxation EPR spectroscopy at zero field, where the sensor is tuned by an amplitude-modulated control field to match the target. The modulation makes detection robust to the sensor's inhomogeneity, while zero-field EPR is naturally robust to the target's inhomogeneity. We demonstrate an efficient EPR measurement on an ensemble of roughly 30000 NV centers. Our method shows the ability to not only acquire unambiguous EPR spectra of free radicals, but also monitor their spectroscopic dynamics in real time.

T. Sh. Abesadze, Z A Tsikoridze

The propagation of a 2π pulse in an ensemble of paramagnetic ions in a magnetic field is analyzed. The paramagnetic part of the magnetooptic activity of the medium contributes to the rotation of the polarization of the light pulse. The Faraday-rotation angle for a 2π pulse which has passed through the medium can be controlled by varying the saturation of the magnetic resonance.

Warren S. Warren