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HL: Fachverband Halbleiterphysik
HL 11: Transport: mainly Theory
HL 11.1: Vortrag
Montag, 14. März 2011, 12:00–12:15, POT 51
Two-dimensional correlation spectroscopy as new tool in noise spectroscopy — •Sebastian Starosielec, Jörg Rudolph, and Daniel Hägele — AG Spektroskopie der kondensierten Materie, Ruhr-Universität Bochum
The measurement of fluctuations, e.g. spin fluctuations via Spin Noise Spectroscopy reveals intrinsic properties of physical systems even in thermal equilibrium. However, the frequency-resolved power spectra do not represent all the system’s dynamical properties. For example, an inhomogeneously broadened spectral feature cannot be distinguished from a purely homogeneously broadened signal by the usually measured noise power spectrum. In 2010, Liu et.al. showed in a theoretical example that the homogeneous linewidth of a single spin in a semiconductor quantum dot can be determined from third-order correlations of the measured time-dependent Faraday-signal even in the presence of inhomogeneous broadening [1].
We have implemented a spectrum analyzer for two-dimensional correlation spectroscopy measuring Scorr(ω,ω′) = ⟨ Iω Iω′ ⟩ − ⟨ Iω ⟩ ⟨ Iω′ ⟩ up to 90 MHz, with Iω being the frequency dependent intensity of the time dependent signal [2]. Scorr allows to distinguish between the homogenous and inhomogenous broadening. We discuss a broad range of application for Scorr including the detection of critical dynamics at second order phase transitions and the detection of coherent signals on a large background of noise.
[1] R.B. Liu et al., New J. Phys. 12, 013018 (2010)
[2] S. Starosielec et al., Rev.Sci.Instrum. 81, (to appear Dec. 2010).