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Main Authors: Cochran, Josiah, Cole, Haley M., Goderya, Hebah, Hao, Zhuoqun, Chang, Yao-Chun, Shaw, Theo, Kargioti, Aikaterini, Shankar, Shyam
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2511.21972
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author Cochran, Josiah
Cole, Haley M.
Goderya, Hebah
Hao, Zhuoqun
Chang, Yao-Chun
Shaw, Theo
Kargioti, Aikaterini
Shankar, Shyam
author_facet Cochran, Josiah
Cole, Haley M.
Goderya, Hebah
Hao, Zhuoqun
Chang, Yao-Chun
Shaw, Theo
Kargioti, Aikaterini
Shankar, Shyam
contents Quantum error correction (QEC) requires ancilla qubits to extract error syndromes from data qubits which store quantum information. However, ancilla errors can propagate back to the data qubits, introducing additional errors and limiting fault-tolerance. In superconducting quantum circuits, Kerr-cat qubits (KCQs), which exhibit strongly biased noise, have been proposed as ancillas to suppress this back-action and enhance QEC performance. Here, we experimentally demonstrate a beamsplitter interaction between a KCQ and a transmon, realizing an effective $\hat{Z}_{cat}\hat{X}_q$ coupling that can be employed for parity measurements in QEC protocols. We characterize the interaction across a range of cat sizes and drive amplitudes, confirming the expected scaling of the interaction rate. These results establish a step towards hybrid architectures that combine transmons as data qubits with noise-biased bosonic ancillas, enabling hardware-efficient syndrome extraction and advancing the development of fault-tolerant quantum processors.
format Preprint
id arxiv_https___arxiv_org_abs_2511_21972
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Experimental signatures of a $\hat{Z}\hat{X}$ beam-splitter interaction between a Kerr-cat and transmon qubit
Cochran, Josiah
Cole, Haley M.
Goderya, Hebah
Hao, Zhuoqun
Chang, Yao-Chun
Shaw, Theo
Kargioti, Aikaterini
Shankar, Shyam
Quantum Physics
Quantum error correction (QEC) requires ancilla qubits to extract error syndromes from data qubits which store quantum information. However, ancilla errors can propagate back to the data qubits, introducing additional errors and limiting fault-tolerance. In superconducting quantum circuits, Kerr-cat qubits (KCQs), which exhibit strongly biased noise, have been proposed as ancillas to suppress this back-action and enhance QEC performance. Here, we experimentally demonstrate a beamsplitter interaction between a KCQ and a transmon, realizing an effective $\hat{Z}_{cat}\hat{X}_q$ coupling that can be employed for parity measurements in QEC protocols. We characterize the interaction across a range of cat sizes and drive amplitudes, confirming the expected scaling of the interaction rate. These results establish a step towards hybrid architectures that combine transmons as data qubits with noise-biased bosonic ancillas, enabling hardware-efficient syndrome extraction and advancing the development of fault-tolerant quantum processors.
title Experimental signatures of a $\hat{Z}\hat{X}$ beam-splitter interaction between a Kerr-cat and transmon qubit
topic Quantum Physics
url https://arxiv.org/abs/2511.21972