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Joerg Wrachtrup

Publications and source records attributed to Joerg Wrachtrup.

22 records · Page 2Linked to original sources
arXiv2013

Mapping spin coherence of a single rare-earth ion in a crystal onto a single photon polarization state

We report on optical detection of a single photostable Ce3+ ion in an yttrium aluminium garnet (YAG) crystal and on its magneto-optical properties at room temperature. The quantum state of an electron spin of the emitting level of cerium ion in YAG can be initialized by circularly polarized laser pulse. Furthermore, its quantum state can be read out by observing temporal behaviour of circularly polarized fluorescence of the ion. This implies direct mapping of the spin quantum state of Ce3+ ion onto the polarization state of the emitted photon and represents one-way quantum interface between a single spin and a single photon.

cond-mat.mtrl-sci↗
arXiv2010

Fluorescence of laser created electron-hole plasma in graphene

We present an experimental observation of non-linear up- and down-converted optical luminescence of graphene and thin graphite subject to picosecond infrared laser pulses. We show that the excitation yields to a high density electron-hole plasma in graphene. It is further shown that the excited charge carries can efficiently exchange energy due to scattering in momentum space. The recombination of the resulting non-equilibrium electron-hole pairs yields to the observed white light luminescence. Due to the scattering mechanism the power dependence of the luminescence is quadratic until it saturates for higher laser power. Studying the luminescence intensity as a function of layer thickness gives further insight into its nature and provides a new tool for substrate independent thickness determination of multilayer flakes.

cond-mat.mtrl-sci↗
arXiv2010

High sensitivity magnetic imaging using an array of spins in diamond

We present a solid state magnetic field imaging technique using a two dimensional array of spins in diamond. The magnetic sensing spin array is made of nitrogen-vacancy (NV) centers created at shallow depths. Their optical response is used for measuring external magnetic fields in close proximity. Optically detected magnetic resonance (ODMR) is readout from a 60x60 $μ$m field of view in a multiplexed manner using a CCD camera. We experimentally demonstrate full two-dimensional vector imaging of the magnetic field produced by a pair of current carrying micro-wires. The presented widefield NV magnetometer offers in addition to its high magnetic sensitivity of 20 nT/$\sqrt{Hz}$ and vector reconstruction, an unprecedented spatio-temporal resolution and functionality at room temperature.

cond-mat.mes-hall↗