Optically and electrically induced dissipation in quantum Hall systems

Abstract

IntroductionThe quantum Hall effect (QHE) [1] is interesting with respect to understanding its physical mechanisms and with respect to its applications. Besides the use of the QHE to maintain a resistance standard on the basis of a macroscopic quantum effect [2], it is also possible to use quantum Hall systems (QHSs) to detect THz waves. This is because the energy gap between adjacent Landau levels (LLs) of ∆E LL ≈ 10 meV corresponds to photons of electromagnetic waves with a wavelength of λ ≈ 125 µm. Thus, sensitive and fast THz detectors with spectral selectivity [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] can be made on the basis of QHSs. However, it takes effort to cool the samples to temperatures at or below 4.2 K and to expose the samples to magnetic fields of typically B > 4 T. As this requires helium cooling of the samples and the application of superconducting magnets, QH THz detectors are not particularly appropriate for widespread use. These detectors have, however, the unique simultaneous properties of high sensitivity,