Flicker Noise Induced by Dynamic Impurities in a Quantum Point Contact

Abstract

We calculate low-frequency noise (LFN) in a quantum point contact (QPC) which is electrostatically defined in a 2D electron gas of a GaAs-AlGaAs heterostructure. The conventional source of LFN in such systems are scattering potentials fluctuating in time acting upon injected electrons. One can discriminate between potentials of different origin -- noise may be caused by the externally applied gate- and source-drain voltages, the motion of defects with internal degrees of freedom close to the channel, electrons hopping between localized states in the doped region, etc. In the present study we propose a model of LFN based upon the assumption that there are many dynamic defects in the surrounding of a QPC. A general expression for the time-dependent current-current correlation function is derived and applied to a QPC with quantized conductance. It is shown that the level of LFN is significantly different at and between the steps in a plot of the conductance vs. gate voltage. On the plateaus, the level of noise is found to be low and strongly model-dependent. At the steps, LFN is much larger and only weakly model-dependent. As long as the system is biased to be at a fixed position relative the conductance step,

26 revtex APR 94-40

References in corpus (3)

• Quantum Transport in Semiconductor Nanostructures
• Low Temperature Transport through a Quantum Dot: The Anderson Model out of Equilibrium
• Electron correlation resonances in the transport through a single quantum level

Cited by in corpus (7)

• 1/f noise: implications for solid-state quantum information
• Low-frequency noise as a source of dephasing of a qubit
• Non-Gaussian low-frequency noise as a source of qubit decoherence
• Decoherence in qubits due to low-frequency noise
• Non-Gaussian dephasing in flux qubits due to 1/f-noise
• Quantum flicker noise in atomic and molecular junctions
• Impurity-induced dephasing of Andreev states