Abstract
Quantum dots are nanoscopic systems, where carriers are confined in all three spatial directions. Such nanoscopic systems are suitable for fundamental studies of quantum mechanics and are candidates for applications such as quantum information processing. It was also proposed that linear arrangements of quantum dots could be used as quantum cascade laser. In this work we study the impact of electron-electron interactions on transport in a spinful serial triple quantum dot system weakly coupled to two leads. We find that due to electron-electron scattering processes the transport is enabled beyond the common single-particle transmission channels. This shows that the scenario in the serial quantum dots intrinsically deviates from layered structures such as quantum cascade lasers, where the presence of well-defined single-particle resonances between neighboring levels are crucial for device operation. Additionally, we check the validity of the Pauli master equation by comparing it with the first-order von Neumann approach. Here we demonstrate that coherences are of relevance if the energy spacing of the eigenstates is smaller than the lead transition rate multiplied by ħ.
Highlights
Quantum dots are nanoscopic systems, where carriers are confined in all three spatial directions
Electron-electron interaction effects in quantum dots have been a topic of active research within the past decades[1,2,3,4,5]
They can be realized in different ways and prominent examples are the gating of a two-dimensional electron gas[15,16,17], cleaved edge overgrowth structures[18], stacked self-organized quantum dots[19], nanowires either with external gates[20,21] or embedded heterostructures[22], or the arrangement of atoms by a scanning tunneling microscope[23]
Summary
Quantum dots are nanoscopic systems, where carriers are confined in all three spatial directions. The restriction of phase space in such low-dimensional structures is reducing the scattering rates substantially and such structures have been suggested for a wide range of applications ranging from quantum information processing[24,25] to quantum cascade lasers[26,27] Electron transport through these structures has been widely used for level spectroscopy[28,29,30,31]. One assumes, that the transport through quantum dot systems is dominated by specific resonances These occur due to the alignment of energy levels in individual dots with those in neighboring dots as well as with the chemical potentials of metallic leads. This provides specific conditions for transport, which are resolved as current or conductance peaks for varying external parameters, such as the voltages at different gates. For systems with many degrees of freedom, such as bulk or layered systems, the continuum of states justifies usually a mean-field description, so that one can apply effective www.nature.com/scientificreports/
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