Big cats: entanglement in 120 qubits and beyond

Fuente: arXiv
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Hauptverfasser: Javadi-Abhari, Ali, Martiel, Simon, Seif, Alireza, Takita, Maika, Wei, Ken X.
Format: Preprint
Veröffentlicht: 2025
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author Javadi-Abhari, Ali
Martiel, Simon
Seif, Alireza
Takita, Maika
Wei, Ken X.
author_facet Javadi-Abhari, Ali
Martiel, Simon
Seif, Alireza
Takita, Maika
Wei, Ken X.
contents Entanglement is the quintessential quantum phenomenon and a key enabler of quantum algorithms. The ability to faithfully entangle many distinct particles is often used as a benchmark for the quality of hardware and control in a quantum computer. Greenberger-Horne-Zeilinger (GHZ) states, also known as Schrödinger cat states, are useful for this task. They are easy to verify, but difficult to prepare due to their high sensitivity to noise. In this Letter we report on the largest GHZ state prepared to date consisting of 120 superconducting qubits. We do this via a combination of optimized compilation, low-overhead error detection and temporary uncomputation. We use an automated compiler to maximize error-detection in state preparation circuits subject to arbitrary qubit connectivity constraints and variations in error rates. We measure a GHZ fidelity of 0.56(3) with a post-selection rate of 28%. We certify the fidelity of our GHZ states using multiple methods and show that they are all equivalent, albeit with different practical considerations.
format Preprint
id arxiv_https___arxiv_org_abs_2510_09520
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Big cats: entanglement in 120 qubits and beyond
Javadi-Abhari, Ali
Martiel, Simon
Seif, Alireza
Takita, Maika
Wei, Ken X.
Quantum Physics
Entanglement is the quintessential quantum phenomenon and a key enabler of quantum algorithms. The ability to faithfully entangle many distinct particles is often used as a benchmark for the quality of hardware and control in a quantum computer. Greenberger-Horne-Zeilinger (GHZ) states, also known as Schrödinger cat states, are useful for this task. They are easy to verify, but difficult to prepare due to their high sensitivity to noise. In this Letter we report on the largest GHZ state prepared to date consisting of 120 superconducting qubits. We do this via a combination of optimized compilation, low-overhead error detection and temporary uncomputation. We use an automated compiler to maximize error-detection in state preparation circuits subject to arbitrary qubit connectivity constraints and variations in error rates. We measure a GHZ fidelity of 0.56(3) with a post-selection rate of 28%. We certify the fidelity of our GHZ states using multiple methods and show that they are all equivalent, albeit with different practical considerations.
title Big cats: entanglement in 120 qubits and beyond
topic Quantum Physics
url https://arxiv.org/abs/2510.09520