Heidelberg 2015 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 42: Quantum Effects: QED II

Q 42.2: Vortrag

Mittwoch, 25. März 2015, 14:45–15:00, B/SR

Analogue Sauter–Schwinger effect in semiconductors — •Malte F. Linder and Ralf Schützhold — Fakultät für Physik, Universität Duisburg-Essen, Lotharstraße 1, D-47057 Duisburg, Germany

The Sauter–Schwinger effect is the non-perturbative excitation of electron-positron pairs from the Dirac quantum vacuum due to high electric field strengths E. This pair creation mechanism can be explained as a tunnelling process of electrons from the Dirac sea into the energy states above the mass gap 2mec2. The tunnelling rate is exponentially suppressed by the factor exp(−π ES/E) with the critical field strength ES≈1018 V/m and thus too small for an experimental verification with currently attainable fields strengths E.

To approach the observation of this quantum effect in the laboratory, we show that a quantitative analogue of the Sauter–Schwinger effect can be realised in semiconductors at low temperatures. The filled valence band acts as Dirac sea, while the empty conduction band corresponds to the positive-energy continuum of the Dirac equation. Since the band gap of a typical semiconductor like GaAs is much smaller than the mass gap 2mec2, the critical field strength for the analogue Sauter–Schwinger effect is much smaller than ES. Furthermore, the pair creation rate can be enhanced by adding time-dependent components (i.e. laser beams or pulses) to the strong static background field (dynamically assisted Sauter–Schwinger effect). The semiconductor analogue could facilitate the study of the Sauter–Schwinger effect and the various assistance mechanisms in the laboratory.

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