Open quantum system description of singlet-triplet qubits in quantum dots

TL;DR

This paper presents a theoretical model for the dissipative dynamics of singlet-triplet qubits in GaAs quantum dots, emphasizing the impact of temperature, environment coupling, and exchange interactions on entanglement.

Contribution

It introduces a detailed quantum system-environment model that captures the effects of temperature and coupling on entanglement dynamics in singlet-triplet qubits.

Findings

Temperature significantly affects entanglement generation.

Reducing environment coupling alters entanglement dynamics.

Exchange coupling and preparation time influence dissipation effects.

Abstract

We develop a theoretical model to describe the dissipative dynamics of singlet-triplet (S-T_0) qubits in GaAs quantum dots. Using the concurrence experimentally obtained as a guide, we show that each logical qubit is coupled to its own environment because the decoherence effect can be described by independent dephasing channels. Given the correct description of the environment, we study the dynamics of concurrence as a function of the temperature, the constant coupling between the system and the environment, the preparation time, and the exchange coupling. Although the reduction of the environment coupling constant modifies the entanglement dynamics, we demonstrate that temperature emerges as a crucial variable and a variation of millikelvins significantly modifies the generation of entangled states. Furthermore, we show that the exchange coupling together with the preparation time strongly affects the entanglement dissipative dynamics.