
Calendar of Physics Talks Vienna
Betadecay total absorption spectroscopy for basic and applied research 
Speaker:  Prof. Dr. Jose TAIN (Instituto de Fisica Corpuscular, Univ. Valencia and C.S.I.C. Edificio de Institutos de Paterna, Valencia, Spain) 
Abstract:  An accurate determination of the betadecay intensity distribution
is important for basic nuclear physics but also in other fields
as astrophysics, reactor technology and neutrino physics.
Total absorption spectroscopy is the only way to obtain accurate
information about the beta intensity distribution for complex decays.
Examples of the information that can be obtained about the
structure of atomic nuclei and of the application of these
data to other fields will be shown. The plans for future work at
existing or planned radioactive beam facilities will be highlighted. 
Date:  Mon, 26.01.2009 
Time:  16:00 
Duration:  60 min 
Location:  Sem. 134A, Freihaus, Turm B, 5. OG 
Contact:  leeb@kph.tuwien.ac.at 
Making an optical clock with magnesium 
Speaker:  Prof. Ernst M. Rasel (Leibniz Universität Hannover) 
Abstract:  In this paper we report on our work directed towards a lattice clock [1] based on magnesium. In the case of the bosonic isotope 24Mg, the acStark shift induced by the optical lattice vanishes for the transition 1S0 &>8594; 3P0 around 432 nm. [2] The linewidth of the strongly forbidden clock transition can be tailored with an external magnetic field [3]. According to [4] this clock would display the lowest blackbody radiation shift of all alkaline earth metals, which is e.g. 10 times smaller than in Sr.
The paper presents the first absolute frequency measurement of the 1S0 & >8594; 3P1 intercombination line in 24Mg [5] based on thermal beam and cold atom interferometry. In combination with previous measurements, the results permit to determine other transitions in the 1S0 & >8594; 3PJ system including the strictly forbidden 1S0 → 3P0 transition. In order to prepare atoms for the frequency measurements, we use laser cooling of the metastable state 3P2 via the transition 3P2& >8594; 3D3, which permits to employ subDopplerlaser cooling techniques. Atoms in this state are now routinely produced in our laboratory by operating synchronously two magnetooptical traps trapping atoms in the ground and metastable atoms respectively [6]. We showed that atoms in the ground state can be transferred in the longlived metastable state with high efficiency by using the intercombination transition 1S0 &>8594; 3P1.
The frequency measurements using cold atoms are performed with a transportable caesium clock and via a telecom fibre link with an optical clock, both provided by the PTB. For this purpose, a frequency transfer with a telecon laser was established via a public fibre link between Hanover and Braunschweig.
[1] M. Takamoto, F.L. Hong, R. Higashi1 and H. Katori, Nature 435, 321324 (2005)
[2] V. D. Ovsiannikov, V. G. Palchikov, A. V. Taichenachev, V. I. Yudin, H. Katori, and M. Takamoto, Phys. Rev. A 75, 020501(R) (2007).
[3] A. V. Taichenachev, V. I. Yudin, C. W. Oates, C. W. Hoyt, Z. W. Barber, and L. Hollberg, Phys. Rev. Lett. 96, 083001 (2006).
[4] S. G. Porsev and A. Derevianko, Phys. Rev. A 74, 020502(R) (2006).[5] J. Friebe, A. Pape, M. Riedmann, K. Moldenhauer, T.E.Mehlstäubler, N. Rehbein, C. Lisdat, E.M. Rasel, and W. Ertmer subm. to Phys. Rev A
[6] J. Friebe, A. Voskrebenzev, A. Pape, M. Riedmann, K. Moldenhauer, E.M. Rasel, and W. Ertmer, in preparation 
Date:  Mon, 26.01.2009 
Time:  17:30 
Duration:  60 min 
Location:  TU Wien, Neues EI8, Pötzl Hörsaal, Stiege 1, EG, Gußhausstraße 2729, 1040 Wien 
Contact:  Prof. Markus Arndt, Universität Wien, Fakultät für Physik, Quantum Optics, Quantum Nanophysics & Quantum Information 
Vienna Theory Lunch Club  Ftheory: Introduction and recent developments 
Speaker:  Andres Collinucci (TU Wien) 
Abstract:  Fourteen years ago, string theory underwent a major paradigm shift when techniques were developed to study the theory non perturbatively, i.e. in its strongly coupled regime. More specifically, the introduction of Dbranes and eventually Mtheory opened up windows that relate the different versions of string theory, in different corners of its parameter space. A year after the idea of Mtheory was conceived, Vafa developed what can be thought of as its obscure partner, known as "Ftheory". Although it is less understood conceptually, Ftheory is a more practical tool for model building, i.e. for trying to make contact with the standard model. Curiously, the year 2008 has seen a revival of "Ftheory", as new results have emerged in the direction of model building.
In this talk, I will give an overall rough picture of Mtheory and F theory without assuming prior knowledge of string theory. Then, as time permits, I will show an explicit Ftheory toy model. Finally, I will summarize the most recent developments in this branch.
Overview Lunch Club 
Date:  Tue, 27.01.2009 
Time:  12:30 
Duration:  60 min 
Location:  University of Vienna, Boltzmanngasse 5, 5th Floor, Large Seminar Room 
Contact:  Max Attems, Daniel Grumiller, Beatrix Hiesmayr 
Qutransitions: probing the critical zero point fluctuations of matter with heavy electron materials 
Speaker:  Piers Coleman (Center for Materials Theory, Rutgers University) 
Abstract:  This seminar will describe the playground for new insights into the nature of "qutransitions"quantum phase transitions provided by heavy fermion physics.
Last century, physicists were profoundly shaken by the discovery of universal
powerlaw correlations at thermal secondorder phase transitions. Today, our
understanding of phase transitions enters the quantum era with the discovery of
quantum phase transitions: phase transitions at absolute zero driven by the violent
jigglings of quantum zeropoint motion squeezed out to macroscopic dimensions.
These transitions occur in a wide range of materials, including ferromagnets,
helium3, ferroelectrics, heavy electron and high temperature superconductors,
and they profoundly alter the properties of a material. While a distant cousin of
classical criticality, quantum criticality is closer in spirit to the Casimir effect of the
electromagnetic vacuum, the extra fermionic dimension of metals converts this into
a major unsolved physics problem.
I'll talk about, and add my perspective on the some of the key questions,
illustrating them with experimental data. In particular:
Does the electron break up at quantum critical point ?
Can quantum critical points become quphases?
and of course 
Is quantum criticality the breading ground for high temperature
superconductivity?

Date:  Wed, 28.01.2009 
Time:  16:30 
Location:  Technische Universität Wien, Seminarraum 138B, 7. OG, Turm C (rot), Wiedner Hauptstraße 810, 1040 Wien 
Contact:  S. BühlerPaschen 
On the geometry of the truncated Heisenberg algebra 
Speaker:  Maja Buric (Belgrad Univ.) (Fakultät für Physik) 
Abstract:  im Rahmen des Seminars für Mathematische Physik 
Date:  Thu, 29.01.2009 
Time:  16:15 
Duration:  60 min 
Location:  Großer Seminarraum, Boltzmanngasse 5, 5. Stock 
Contact:  H. Grosse 
