CQT PhD Thesis Defense by Ritayan Roy
Title: An integrated atom chip for the detection and manipulation of cold atoms using a two-photon transition
Date/Time: Wed 05-Aug, 4:00pm
Venue: CQT Level 3 Conference Room, S15-03-18
We have designed and constructed an atom chip experiment for background free, high resolution atom detection using a two-photon transition. The chip consists of an atomic
conveyor belt, which allows deterministic positioning of the atom cloud. The work emphasises on the application of an atomic conveyor belt in order to move the ultracold
atoms precisely in a plane parallel to the surface of the chip and bring it near to a microoptics for detection and manipulation using a two-photon transition. A two-photon transition scheme for the Rubidium (Rb) 5S1=2 to 4D5=2 at 1033.3 nm is spectroscopically observed for the rst time, which can be used for the detection and manipulation of the ultracold atoms. This transition could be used as a frequency standard for ber lasers, creation of far-red detuned dipole trap (o resonant from the two-photon transition), for selective excitation of few atoms in a cloud (in the Rayleigh volume) and for super-resolution imaging. Detection of the atoms would be background free as excitation happens for 5S1=2 to 4D5=2 transition at 1033.3 nm and atom decays back to the ground state via 5P3=2 level, emitting photon of the wavelength 780.2 nm.
CQT Talk by Barbara Kraus, Universität Innsbruck, Austria
Title: Some aspects of multipartite entanglement
Date/Time: Thu 06-Aug, 10:00am
Venue: CQT Level 3 Seminar Room, S15-03-15
The potentiality of quantum systems to be correlated leads to many fascinating applications of quantum information. For pure states, these correlations coincide with entanglement. Hence, the qualification and quantification of multipartite entanglement is one of the central topics within quantum information. Despite its relevance, however, many very fundamental questions in this context are still unanswered.
In this talk I will focus on some aspects of multipartite entanglement.
In particular, I will present a generalization of the notion of maximally entangled bipartite states to the multipartite case and will demonstrate a new approach of quantifying entanglement of few-partite systems. More precisely, I will present two new operational classes of entanglement measures. Due to their clear operational meaning, these measures are applicable to systems of arbitrary sizes and dimensions, being prepared in either pure or mixed states. I will demonstrate how these measures can be utilized to uniquely characterize the entanglement contained in few-body systems, for which they can be easily computed.