Immersed quantum systems:Lamb shift and bound Bose polarons

8 marzo 2016
Versione stampabile

At 11.00
Venue: Department of Physics - Seminar Room Fisica Teorica - 2 nd floor

  • Prof. Markus Oberthaler - (Universität Heidelberg)

The experimental realization of two component quantum gases offers a unique way for the study of dynamics of immersed quantum systems. The employed atomic system sodium-lithium allows the exploration of the weak coupling limit which is well captured by the Fröhlich Hamiltonian but makes the observable effects such as the increase of the effective mass experimentally challenging since they are very small. The implementation of a novel motional Ramsey spectroscopy strategy opens now the route for accessing these relative mass changes in the order of 104.
We will report on the results employing this method for the investigation of the motional coherence of fermions in a bosonic bath [1]. Our latest finding reveal that in the limit of strong confinement the effective mass picture is no sufficient to explain the observation of the energy splitting of the motional states. Indeed the selfenergy has to be properly calculated revealing that additional to the energy shift of the motional degrees of freedom due the increase mass also the phenomenon of Lamb shift becomes accessible. With our system employing fermionic and bosonic impurities immersed in a bosonic bath we can identify the Lamb shift of bound Bose polarons and with that detect for the first time directly the theoretically discussed phononic Lamb shift for bound polarons in condensed matter systems [2]. 
We will also give a short report on the recent results on using time reversal of nonlinear many particle dynamics to beat the quantum limited readout of a phase measurement. This is directly connected to the active atom interferometer scheme known as SU(1,1) interferometry [3].
[1] Motional Coherence of Fermions Immersed in a Bose Gas, R. Scelle, et al. Phys.Rev.Lett. 111, 070401 (2013).
[2] Ground-State Energy of Bound Polarons, P.M. Platzman, Phys.Rev. 125, 1961 (1962).
[3] Quantum-enhanced sensing based on time reversal of non-linear dynamics, D. Linnemann et al. arXiv:1602.07505