# Entanglement loss in molecular quantum-dot qubits due to interaction with the environment

## TL;DR

This paper investigates how environmental interactions cause entanglement loss in molecular quantum-dot qubits, analyzing the dynamics of entanglement decay and its dependence on environmental geometry with implications for quantum computing.

## Contribution

It models the entanglement dynamics of two quantum-dot qubits interacting with complex, randomly oriented environments, revealing universal scaling behaviors of entanglement loss.

## Key findings

- Entanglement decays over time depending on environmental geometry.
- Disentanglement times can be estimated with realistic molecular parameters.
- Results suggest universal behavior in entanglement loss across different configurations.

## Abstract

We study quantum entanglement loss due to environmental interaction in a condensed matter system with a complex geometry relevant to recent proposals for computing with single electrons at the nanoscale. We consider a system consisting of two qubits, each realized by an electron in a double quantum dot, which are initially in an entangled Bell state. The qubits are widely separated and each interacts with its own environment. The environment for each is modeled by surrounding double quantum dots placed at random positions with random orientations. We calculate the unitary evolution of the joint system and environment. The global state remains pure throughout. We examine the time dependence of the expectation value of the bipartite Clauser-Horne-Shimony-Holt (CHSH) and Brukner-Paunkovi\'c-Rudolph-Vedral (BPRV) Bell operators and explore the emergence of correlations consistent with local realism. Though the details of this transition depend on the specific environmental geometry, we show how the results can be mapped on to a universal behavior with appropriate scaling. We determine the relevant disentanglement times based on realistic physical parameters for molecular double-dots.