Entangling four logical qubits beyond break-even in a nonlocal code

Fuente: arXiv
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Autori principali: Hong, Yifan, Durso-Sabina, Elijah, Hayes, David, Lucas, Andrew
Natura: Preprint
Pubblicazione: 2024
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author Hong, Yifan
Durso-Sabina, Elijah
Hayes, David
Lucas, Andrew
author_facet Hong, Yifan
Durso-Sabina, Elijah
Hayes, David
Lucas, Andrew
contents Quantum error correction protects logical quantum information against environmental decoherence by encoding logical qubits into entangled states of physical qubits. One of the most important near-term challenges in building a scalable quantum computer is to reach the break-even point, where logical quantum circuits on error-corrected qubits achieve higher fidelity than equivalent circuits on uncorrected physical qubits. Using Quantinuum's H2 trapped-ion quantum processor, we encode the GHZ state in four logical qubits with fidelity $ 99.5 \pm 0.15 \% \le F \le 99.7 \pm 0.1\% $ (after postselecting on over 98% of outcomes). Using the same quantum processor, we can prepare an uncorrected GHZ state on four physical qubits with fidelity $97.8 \pm 0.2 \% \le F\le 98.7\pm 0.2\%$. The logical qubits are encoded in a $[\![ 25,4,3 ]\!]$ Tanner-transformed long-range-enhanced surface code. Logical entangling gates are implemented using simple swap operations. Our results are a first step towards realizing fault-tolerant quantum computation with logical qubits encoded in geometrically nonlocal quantum low-density parity check codes.
format Preprint
id arxiv_https___arxiv_org_abs_2406_02666
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Entangling four logical qubits beyond break-even in a nonlocal code
Hong, Yifan
Durso-Sabina, Elijah
Hayes, David
Lucas, Andrew
Quantum Physics
Quantum error correction protects logical quantum information against environmental decoherence by encoding logical qubits into entangled states of physical qubits. One of the most important near-term challenges in building a scalable quantum computer is to reach the break-even point, where logical quantum circuits on error-corrected qubits achieve higher fidelity than equivalent circuits on uncorrected physical qubits. Using Quantinuum's H2 trapped-ion quantum processor, we encode the GHZ state in four logical qubits with fidelity $ 99.5 \pm 0.15 \% \le F \le 99.7 \pm 0.1\% $ (after postselecting on over 98% of outcomes). Using the same quantum processor, we can prepare an uncorrected GHZ state on four physical qubits with fidelity $97.8 \pm 0.2 \% \le F\le 98.7\pm 0.2\%$. The logical qubits are encoded in a $[\![ 25,4,3 ]\!]$ Tanner-transformed long-range-enhanced surface code. Logical entangling gates are implemented using simple swap operations. Our results are a first step towards realizing fault-tolerant quantum computation with logical qubits encoded in geometrically nonlocal quantum low-density parity check codes.
title Entangling four logical qubits beyond break-even in a nonlocal code
topic Quantum Physics
url https://arxiv.org/abs/2406.02666