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OSA Student Chapter Meeting

SPEAKER: Mohammadreza Rezaee
TITLE: Nanoscale in vivo thermometry: photoluminescence of color centers in nanodiamonds as nanosensors
Color centers in diamond are point defects in the lattice structure and occur naturally or can be artificially introduced in the crystal lattice during the sensitizing process. They have attracted tremendous attention due to their superior properties such as extremely high photostability, chemical inertness and spin-dependent magneto-optical characteristics. Although the main attraction here is the promising possibility to utilize these color centers as qubits in the quantum information processing, color centers and in particular nitrogen-vacancy centers can be employed as nanoscale sensors to measure and map the magnetic field and temperature in different environments. Optical properties of the NV centers such as the luminescence intensity are highly sensitive to the environmental parameters such as electric and magnetic field or the temperature in which the nanodiamonds are embedded. In this sense nanodiamonds small size and high thermal conductivity make them reliable nanoscale thermometers. The possibility of synthesizing nanodiamonds with few nanometers in size which include a single or multiple NV centers make them excellent candidates as highly sensitive nanoscale sensors for measuring and mapping the temperature over a wide range. Since they are small enough and chemically not very reactive, these NV centers can be introduced to the cellular medium via different techniques such as nanoneedles or making them biocompatible through surface biofunctionalization. These properties make it possible to use the NV centers to measure the temperature inside a living organism without major interference with its natural functions. This is possible due to chemical inertness which makes this nanosensors very low in toxicity. Six electron paramagnetic system with long spin coherence time of the NV centers in nanodiamonds have been successfully employed as nanosensors with mK order of magnitude temperature resolution to measure the temperature within a living cell as well as integrated circuits and semiconductors with superb spatial resolution and are proven to be extremely sensitive. This possibility can open new opportunities in different branches of life science and further enhance our knowledge of cellular thermodynamics by facilitating high resolution in vitro temperature measurements.

SPEAKER: Sean O'Connor
TITLE: Discovery of Spatiotemporal Optical Vortices in Laser Pulses
Dr. Milchberg's group at the University of Maryland have discovered a new type of optical vortex called Spatiotemporal Optical Vortices (STOVs) using numerical modeling and experiments with ultrafast pulses. In these STOV beams, the phase circulates in the direction of the beam's propagation which results in phase discontinuities in a toroid shape around the laser pulse.

*References N. Jhajj et al., PHYS. REV. X 6, 031037 (2016) http://www.osa-opn.org/home/newsroom/2016/september/optical_smoke_rings"in_laser_pulses/

Thursday, October 6, 2016
IQSE 578, 12:30 noon
Mitchell Physics Building

Department of Physics and Astronomy
Institute for Quantum Science and Engineering
Texas A&M University

(Pizza lunch as usual. Newcomers welcome!)

Host: Sasha Zhdanova