Entanglement induced by Heisenberg exchange between an electron in a nested quantum dot and a qubit with relative motion

TL;DR

This paper investigates how a nested quantum dot structure influences entanglement generated by Heisenberg exchange between an electron and a moving qubit, revealing conditions for enhanced and tunable entanglement.

Contribution

It introduces a nested quantum dot design that allows improved control and understanding of entanglement dynamics induced by exchange interactions with a moving qubit.

Findings

Excited scattering states produce more entanglement than bound states.

Long-range interactions yield significant entanglement regardless of qubit direction.

Initial spin angles determine maximum mutual information without the nested dot.

Abstract

We propose a nested quantum dot structure for improved control of entanglement induced by the Heisenberg exchange between an electron and a qubit with relative motion. The entanglement is quantified by the mutual information (MI). The electron, initially prepared in the ground state, generally produces greater entanglement when excited to the scattering state compared to remaining in the bound state. In the bound state, the final entanglement oscillates as a function of the qubit speed and can be tuned accordingly. In the case of long-range interaction, the normalized exchange distribution leads to substantial final entanglement, independent of the qubit moving direction, indicating that even very weak but prolonged exchange can still generate significant entanglement. In the case of short-range interaction, different moving directions lead to varying MI values. We also consider the scenario without the nested dot and find that the same maximum (among all times) MI is pre-determined solely by the initial angle between the spins. In this case, the entanglement exhibits different growth characteristics during different phases. The saturation of the MI mimics that of a strict zero-dimensional quantum dot, where exchange and time are combined into a single parameter, the amount of interaction.