Slow and Fast Electron Channels in a Coherent Quantum Dot Mixer

Abstract

We describe a means to realize slow and fast electron channels by coherent mixing of single-particle levels in quantum dots. The underlying physics, which gives insight into state superposition, can potentially be realized in multi-dot structures with complex gate control. However, we employ vertical double dot structures and in our scheme the mixing of single-particle levels arises because of natural perturbations in the confining potential of the high-symmetry dots. Additionally, because of the intrinsic properties of a Fock-Darwin-like spectrum, we utilize a magnetic field to bring multiple single-particle energy levels into close proximity. We determine single-electron resonant tunneling times (effectively dwell times when on resonance) that are either extended in the slow channel or shortened in the fast channel. Most dramatically, for the slow channel, slowdown factors of 10 and single-electron resonant tunneling times extended into the ms range are demonstrated in all systems of two, three, and four mixed single-particle states investigated here. #

Interference effects in the Coulomb blockade regime: Current blocking and spin preparation in symmetric nanojunctions

“…The triple dot SET has been recently in the focus of intense theoretical 14,15,[37][38][39][40][41] and experimental [42][43][44][45] investigation due to its capability of combining incoherent transport characteristics and signatures of molecular coherence. The triple dot ISET that we consider here ͑Fig.…”

Master equation based steady-state cluster perturbation theory

“…31,32 Experimentally the stability diagram has been explored 34 alongside characterisation and transport measurements. 29,35,36 The negative differential conductance has been observed in a device aimed as a quantum rectifier. 127 Theoretically the study of the nonequilibrium behaviour of such a device has become an active field recently.…”

“…Prompted by these formidable advances in experimental techniques, the characterization of transport through e.g. molecules bound by anchor groups to metal electrodes, 21,27,28 heterostructures 29,30 or nano structures on two-dimensional substrates 29,[31][32][33][34][35][36] has become feasible. These constitute the foundation for future applications in electronic devices based on single electron tunnelling, 37 quantum interference effects, [38][39][40][41][42][43][44] spin control 45,46 or even quantum manybody effects 9,10,12,47,48 like Kondo 49 behaviour.…”