One dimensional electron spin imaging for single spin detection and manipulation using a gradient field

Abstract

The ability to resolve molecules individually has many potential applications. These include understanding the local environments of single molecules including details of their interactions with surroundings. The ability to individually address and manipulate the spin states is also required for spin based quantum information processing. Although optical detection techniques, such as optically detected electron spin resonance (ESR) seem very powerful in these contexts, multiple molecules in the focal volume of a diffraction limited confocal microscope spot cannot in general be resolved individually. Here we propose to solve this problem using optically detected ESR imaging based on the use of high field gradients. In the present research, subwavelength single molecule imaging is demonstrated by using the optically detected ESR technique and the optically detected electron spin echo envelope modulation (ESEEM) technique. Ultra fast Rabi nutation experiments are also performed to demonstrate the feasibility of fast spin manipulations at a low microwave power. Micrometer sized gradient coils, together with micrometer sized co-planar microstrip transmission lines, are designed and fabricated by optical lithography in order to produce the necessary high magnetic field gradients. These fabricated devices are used to demonstrate this subwavelength imaging technique by imaging single electron spins of the nitrogen-vacancy (NV) defect in diamond. In this demonstration, multiple NV defects, unresolved in a single focal volume of a diffraction limited microscope are successfully resolved by the optically detected ESR techniques. Specifically, two neighboring NV defects separated by about 170nm are resolved. Ultra Fast electron spin nutation with an oscillation period of 1.33ns is also achieved by the high microwave magnetic field induced by the current flowing through the fabricated co-planar microstrip lines. These optically detected ESR and ESEEM techniques combined with the micrometer sized gradient coil may find many applications, including single molecule imaging and quantum information processing.