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Ultrafast coherent dynamics in optically driven BCS systems

Title data

Papenkort, Thomas ; Kuhn, Tilmann ; Axt, Vollrath M.:
Ultrafast coherent dynamics in optically driven BCS systems.
In: Physica Status Solidi B. Vol. 246 (2009) Issue 2 . - pp. 325-328.
ISSN 1521-3951
DOI: https://doi.org/10.1002/pssb.200880317

Abstract in another language

We present simulations of the nonlinear ultrafast dynamics of a BCS superconductor. Pump–probe measurements and a coherent control technique are employed to gain insight into the excitation dynamics of the superconductor. In pump–probe spectra the energy gap of the superconductor is visible as an area of low absorption followed by a sharp peak. Excitation with a short laser pulse lowers the gap and thereby shifts the peak. However, the numerical calculations reveal the emergence of a nonadiabatic regime on short time scales: A sufficiently short pump pulse causes a fast oscillation of the modulus of the BCS order parameter. Although this parameter can usually be identified with the energy gap, its oscillation remains hidden in pump-probe spectra, i.e., the gap observed in the spectra is independent of the delay time. Instead the gap in the spectra corresponds to the mean value of the oscillation. By making use of a coherent control technique involving a second pump pulse, this oscillation may be made visible in probe spectra. This is because the reaction of the BCS system to the second pump pulse depends strongly on its instantaneous state at the time of the impact of this pulse. In particular the gap observed in the spectra after the second pump pulse for varying pump–pump delay times mimics the oscillation of the order parameter after the first pump pulse.

Further data

Item Type: Article in a journal
Refereed: Yes
Keywords: coherent control; Terahertz excitation; Terahertz control; BCS superconductors; nonadiabatic dynamics; Oscillations of the order parameter; pump-probe; coherent dynamics; laser-driven superconductors; ultrafast dynamics; order parameter control; gap control
Institutions of the University: Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics
Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics > Chair Theoretical Physics III > Chair Theoretical Physics III - Univ.-Prof. Dr. Martin Axt
Faculties
Faculties > Faculty of Mathematics, Physics und Computer Science
Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics > Chair Theoretical Physics III
Result of work at the UBT: Yes
DDC Subjects: 500 Science > 530 Physics
Date Deposited: 30 Oct 2017 12:14
Last Modified: 30 Oct 2017 12:14
URI: https://eref.uni-bayreuth.de/id/eprint/40205