Quantum Speed Limit Time in two-qubit system by Dynamical Decoupling Method

TL;DR

This paper investigates how periodic dynamical decoupling can effectively control the quantum speed limit in a two-qubit system under dephasing, enabling ultra-fast quantum processes for quantum computing.

Contribution

It demonstrates that applying PDD to both qubits can completely eliminate dephasing effects and significantly accelerate quantum evolution, with potential applications in high-speed quantum gates.

Findings

Applying PDD to both qubits removes dephasing effects entirely.

Single-qubit PDD is less efficient but still effective.

Ultra-high speed quantum evolution is achievable with many pulses.

Abstract

Quantum state change can not occurs instantly, but the speed of quantum evolution is limited to an upper bound value, called quantum speed limit (QSL). Engineering QSL is an important task for quantum information and computation science and technologies. This paper devotes to engineering QSL and quantum correlation in simple two-qubit system suffering dephasing via Periodic Dynamical Decoupling (PDD) method in both Markovian and non-Markovian dynamical regimes. The results show that when decoupling pulses are applied to both qubits this method removes all undesirable effects of the dephasing process, completely. Applying the PDD on only one of the qubits also works but with lower efficiency. Additionally, ultra-high speedup of the quantum processes become possible during the pulse application period, for enough large number of pulses. The results is useful for high speed quantum gate implementation application.