Numerical Simulation of Quantum Dot Interferometer in Kondo Regime

We propose a numerical method to simulate a transport experiment using a quantum dot interferometer made of two quantum wires in parallel [S. Takada et al., Phys. Rev. Lett. 113, 126601 (2014)]. The wires are partly tunnel-coupled to each other to form a mesoscopic ring with an embedded quantum dot. Our method consists of two stages. In the first stage, we represent the experimental system with a tight-binding model by discretizing the space. The conductance around a Coulomb peak is evaluated as a function of magnetic field in four-terminal geometry, where the Coulomb interaction is irrelevant. We show clear Aharonov–Bohm (AB) oscillations despite the multiple conduction channels and magnetic field inside the wires. In the second stage, we adopt a model of double quantum dot (DQD) in parallel. The model parameters are chosen to reproduce the Coulomb peak and AB oscillations obtained in the first stage in the absence of the Coulomb interaction U. Finally, we calculate the conductance in the Kondo valley using the DQD model in the presence of U. We observe phase locking at π=2, which is consistent with experimental results.