Parallel-coupled Double Quantum Dot Research Articles

Time-dependent resonant tunnelling for parallel-coupled double quantum dots

We derive the quantum rate equations for an Aharonov–Bohm interferometer with twovertically coupled quantum dots embedded in each of two arms by means of thenonequilibrium Green function in the sequential tunnelling regime. Based onthese equations, we investigate time-dependent resonant tunnelling under a smallamplitude irradiation and find that the resonant photon-assisted tunnelling peaksin photocurrent demonstrate a combination behaviour of Fano and Lorentzianresonances due to the interference effect between the two pathways in this parallelconfiguration, which is controllable by threading the magnetic flux inside this device.

Properties of the ground state of parallel double quantum dots embedded in a mesoscopic ring

We theoretically study the properties of the ground state of the parallel-coupled double quantum dot embedded in a mesoscopic ring in the Kondo regime by means of the two-impurity Anderson Hamiltonian. The Hamiltonian is solved by means of the slave-boson mean-field theory. Our results that when the system goes into the strong coupling regime, two parallel dots can are coupled coherently, which leads to an enhanced Kondo effect and a giant persistent current emerging in this system. This double quantum dot device might be a possible candidate for future device applications.

Transition between quantum states in a parallel-coupled double quantum dot.

Strong electron and spin correlations in a double quantum dot (DQD) can give rise to different quantum states. We observe a continuous transition from a Kondo state exhibiting a single-peak Kondo resonance to another exhibiting a double peak by increasing the interdot coupling (t) in a parallel-coupled DQD. The transition into the double-peak state provides evidence for spin entanglement between the excess electrons on each dot. Toward the transition, the peak splitting merges and becomes substantially smaller than t because of strong Coulomb effects. Our device tunability bodes well for future quantum computation applications.