Observation of Collective Lamb Shift in Single-Photon Superradiance
Abstract
In 1955 Willis Lamb received the noble prize, for the experimental observation of the ‘Lamb-shift’, a tiny energy shift of the bound atomic levels due to the interaction of the electron with virtual photons, which is at the heart of quantum electrodynamics and subsequent quantum field theories. However, Lamb shift was observed only for atomic gases. Although predicted about 35 years ago, the ‘collective lamb shift’ in real solid state samples was not observed, because (1) the atom-atom interaction masks the observable shift, ((2) the sample should be optically thin upon absorption and optically thick upon emission – such a sample was not realized in practice. We have overcome these problems by embedding a 57Fe (14.4 keV nuclear resonance) probe layer at the centre of a planar wave guide and exciting the 57Fe nuclei to a superradiant state by 14.4 keV single-photon pulsed-synchrotron radiation at a grazing incidence geometry (at the 1st wave guide mode of the cavity). Finally, by using the (coherent elastic) nuclear resonant scattering combined with Doppler energy analysis, we have measured, for the first time, the collective Lamb shift and the single-photon superradiance of 57Fe nuclei in two wave guide samples with 0.6 nm and 1.2 nm thickness of the 57Fe layer, respectively [1]. The details will be presented. Our observation and experimental method opens a new field for the study of light-mater interaction and the study of the Lamb shift and superradiance in quantum optics.[1] R. Röhlsberger, K. Schlage, B. Sahoo, S. Couet and R. Rüffer, Science, 328 (2010) 1248.
25/01/2011 at 4:00 pm
Sankhadeep Chakraborty
Seminar (String Theory)
Lecture Hall Block A, Institute of Physics
Document Date:
BPS configuration and vacuum moduli space of BLG model
In this talk I will discuss the use of the hidden G2(2)symmetry to construct black strings of minimal N=1 D=5 supergravity. Iwill present the construction of the most general black string withthree-commuting Killing symmetries in this theory. This solution has anumber of implications for extremal as well as non-extremal blackrings. Using a particular limit of this black string solution and theassociated dual Maldacena-Stominger-Witten (MSW) CFT, I will present aproposal for the microscopic realization of the Kerr-CFTcorrespondence.
