Influence of errors on the transport of quantum information through distant quantum dot spin qubits

The ability to connect distant qubits plays a role in quantum computing and systems candidates for quantum computation must be able to interact their constituent qubits. We model the quantum dot spin qubits by a spin chain with nearest-neighbors interaction. Within this model, we interact distant qubits by consecutive SWAP gates. The SWAP gate exchanges the information of two different qubits and it is obtained by a time-dependent pulse. Also, we implement the CNOT gate, which is fundamental to universal quantum computation. These gates are applied in a system free from decoherence, which provides a fidelity with high accuracy. Furthermore, we analyze the situation where dephasing, amplitude-damping, and depolarizing types of errors occur in each site of the chain. We found that the order of the SWAP and CNOT gates is important and it can lead to a relevant difference in fidelity when the number of qubits is large.(c) 2022 Elsevier B.V. All rights reserved.

Automated summary

This study investigates the impact of the ability to connect distant qubits on the performance of quantum computing systems. By using a spin chain model and swap gates, interactions between quantum bits are implemented, and these gates are applied in a decoherence-free system to improve fidelity. The results show that the order of swap gates and CNOT gates is crucial for fidelity when the number of qubits is large.