Evolution of different orders of coherence of a three-qubit system and their protection via dynamical decoupling on an NMR quantum processor

Fuente: arXiv
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Main Authors: Gautam, Akanksha, Dorai, Kavita, Arvind
Format: Preprint
Published: 2024
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author Gautam, Akanksha
Dorai, Kavita
Arvind
author_facet Gautam, Akanksha
Dorai, Kavita
Arvind
contents We generate different orders of quantum coherence in a three-qubit NMR system and study their dynamics in the presence of inherent noise. Robust dynamical decoupling (DD) sequences are applied to preserve the different coherence orders. Initially, DD sequences are implemented simultaneously on all three spins, which effectively protects third-order coherence; however, other coherence orders decay rapidly instead of being preserved. The robust DD sequences were suitably modified in order to preserve other coherence orders. These sequences are applied to the two participating qubits that generate each zero and second order coherence, ensuring their effective preservation. In contrast, first-order coherence is preserved more efficiently when DD sequences are applied exclusively on the qubit responsible for generating it. Instead of performing full state tomography, coherence orders are measured directly using single pulses. The robust DD protection schemes are finally applied to successfully protect two-qubit entanglement in three-qubit star states.
format Preprint
id arxiv_https___arxiv_org_abs_2411_07187
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Evolution of different orders of coherence of a three-qubit system and their protection via dynamical decoupling on an NMR quantum processor
Gautam, Akanksha
Dorai, Kavita
Arvind
Quantum Physics
We generate different orders of quantum coherence in a three-qubit NMR system and study their dynamics in the presence of inherent noise. Robust dynamical decoupling (DD) sequences are applied to preserve the different coherence orders. Initially, DD sequences are implemented simultaneously on all three spins, which effectively protects third-order coherence; however, other coherence orders decay rapidly instead of being preserved. The robust DD sequences were suitably modified in order to preserve other coherence orders. These sequences are applied to the two participating qubits that generate each zero and second order coherence, ensuring their effective preservation. In contrast, first-order coherence is preserved more efficiently when DD sequences are applied exclusively on the qubit responsible for generating it. Instead of performing full state tomography, coherence orders are measured directly using single pulses. The robust DD protection schemes are finally applied to successfully protect two-qubit entanglement in three-qubit star states.
title Evolution of different orders of coherence of a three-qubit system and their protection via dynamical decoupling on an NMR quantum processor
topic Quantum Physics
url https://arxiv.org/abs/2411.07187