Transition between Quantum States in a Parallel-Coupled Double-Quantum-Dot

TL;DR

This paper investigates how increasing inter-dot coupling in a parallel-coupled double quantum dot induces a transition from a single-peak Kondo state to a double-peak state, revealing spin-entanglement and potential for quantum computing.

Contribution

It demonstrates a controllable transition between quantum states in a double quantum dot, highlighting the role of inter-dot coupling and Coulomb effects in quantum state manipulation.

Findings

Transition from single-peak to double-peak Kondo resonance observed

Evidence of spin-entanglement between electrons on each dot

Device tunability supports future quantum computation applications

Abstract

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 inter-dot-coupling (t) in a parallel-coupled DQD. The transition into the double-peak state provides evidence for spin-entanglement between the excess-electron 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.