Events at Physics
Events on Thursday, May 4th, 2017
- R. G. Herb Condensed Matter Seminar
- Coherent defects in diamond
- Time: 10:00 am
- Place: 5310 Chamberlin
- Speaker: Nathalie de Leon, Princeton
- Abstract: Engineering coherent systems is a central goal of quantum science and quantum information processing. Point defects in diamond known as color centers are a promising physical platform. As atom-like systems, they can exhibit excellent spin coherence and can be manipulated with light. As solid-state defects, they can be produced at high densities and incorporated into scalable devices. Diamond is a uniquely excellent host: it has a large band gap, can be synthesized with sub-ppb impurity concentrations, and can be isotopically purified to eliminate magnetic noise from nuclear spins. Specifically, the nitrogen vacancy (NV) center has been used to has been used to demonstrate basic building blocks of quantum networks and quantum computers, and has been demonstrated to be a highly sensitive, non-invasive magnetic probe capable of resolving the magnetic field of a single electron spin with nanometer spatial resolution. However, realizing the full potential of these systems requires the ability to both understand and manipulate diamond as a material. I will present two recent results that demonstrate how carefully tailoring the diamond host can dramatically improve the performance of color centers for various applications.
First, currently-known color centers either exhibit long spin coherence times or efficient, coherent optical transitions, but not both. We have developed new methods to control the diamond Fermi level in order to stabilize a new color center, the neutral charge state of the silicon vacancy (SiV) center, which exhibits both the excellent optical properties of the negatively charged SiV center and the long spin coherence times of the NV center, making it a promising candidate for applications as a single atom quantum memory for long distance quantum communication.
Second, color centers placed close to the diamond surface can have strong interactions with molecules and materials external to the diamond. However, uncontrolled surface termination and contamination can degrade the color center properties and give rise to noise that obscures the signal of interest. I will describe our recent efforts to stabilize shallow NV centers within 5 nm of the surface using new surface processing and termination techniques. These highly coherent, shallow NV centers will provide a platform for sensing and imaging down to the scale of single atoms.
- Host: Brar
- Astronomy Colloquium
- The IllustrisTNG Simulations: Elemental Evolution in Cosmological Simulations
- Time: 3:30 pm - 5:00 pm
- Place: 4421 Sterling Hall, Cookies and Coffee at 3:30 PM, Talk at 3:45 PM
- Speaker: Jill Naiman, CfA Boston
- Abstract: I will give an overview of some of the new features of the IllustrisTNG models - a set of gravitational, hydrodynamical, MHD cosmological simulations aimed at resolving from the formation of galaxy clusters down to the structures of Milky Way dwarf galaxies. A brief overview of AREPO, the code used in these simulations, and updates from its first cosmological implementation in the Illustris simulations will be presented. I will conclude with some preliminary results on the distribution of elements in our simulations, in particular, the distribution of Europium in Milky Way sized galaxies.
- Host: Prof Elena Donghia