Protecting Quantum Information in Quantum Dot Spin Chains by Driving Exchange Interactions Periodically

TL;DR

This paper analyzes how periodic driving of exchange interactions in quantum dot spin chains can induce time-crystalline behavior, which enhances the protection and manipulation of multi-spin states for quantum computing.

Contribution

It provides a detailed Floquet analysis of exchange-driven dynamics in quantum dot arrays, demonstrating improved state protection and high-fidelity gate construction.

Findings

Emergent time-crystalline behavior protects spin states.

Periodic driving enhances quantum state stability.

High-fidelity CZ gate between singlet-triplet qubits.

Abstract

Recent work has demonstrated a new route to discrete time crystal physics in quantum spin chains by periodically driving nearest-neighbor exchange interactions in gate-defined quantum dot arrays [arXiv:2006.10913]. Here, we present a detailed analysis of exchange-driven Floquet physics in small arrays of GaAs quantum dots, including phase diagrams and additional diagnostics. We also show that emergent time-crystalline behavior can benefit the protection and manipulation of multi-spin states. For typical levels of nuclear spin noise in GaAs, the combination of driving and interactions protects spin-singlet states beyond what is possible in the absence of exchange interactions. We further show how to construct a time-crystal-inspired CZ gate between singlet-triplet qubits with high fidelity. These results show that periodically driving exchange couplings can enhance the performance of quantum dot spin systems for quantum information applications.