Coherent transport of spin by adiabatic passage in quantum dot arrays

TL;DR

This paper presents a robust adiabatic protocol for transferring spin states across quantum dot arrays, enabling high-fidelity quantum information processing and entanglement generation in scalable quantum systems.

Contribution

It introduces spin-CTAP, a new adiabatic transfer method for spin states in quantum dots, with robustness to imperfections and applications in entanglement creation.

Findings

Achieves >95% fidelity in spin state transfer.

Enables conditional GHZ state generation.

Robust against realistic noise models.

Abstract

We introduce an adiabatic transfer protocol for spin states in large quantum dot arrays that is based on time-dependent modulation of the Heisenberg exchange interaction in the presence of a magnetic field gradient. We refer to this protocol as spin-CTAP (coherent transport by adiabatic passage) in analogy to a related protocol developed for charge state transfer in quantum dot arrays. The insensitivity of this adiabatic protocol to pulse imperfections has potential advantages for reading out extended spin qubit arrays. When the static exchange interaction varies across the array, a quantum-controlled version of spin-CTAP is possible, where the transfer process is conditional on the spin states in the middle of the array. This conditional operation can be used to generate N-qubit entangled GHZ states. Using a realistic noise model, we analyze the robustness of the spin-CTAP operations and find that high-fidelity (>95%) spin eigenstate transfer and GHZ state preparation is feasible in current devices.