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Main Authors: Miller, B. T., Orr, Lindsay, Metelmann, A., Lecocq, F.
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2603.12312
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author Miller, B. T.
Orr, Lindsay
Metelmann, A.
Lecocq, F.
author_facet Miller, B. T.
Orr, Lindsay
Metelmann, A.
Lecocq, F.
contents High fidelity qubit readout is a cornerstone for quantum information protocols. In traditional superconducting qubit readout, a chain of microwave amplifiers and nonreciprocal components aid in detecting the qubit's state with tolerable added noise and backaction. However, the loss, size, and magnetic field of standard nonreciprocal components have sparked a decades-long search for more efficient and scalable alternatives. One prominent approach employs networks of parametrically coupled modes to achieve nonreciprocity. While this class of devices can be directly integrated with the qubit's readout cavity, current understanding of the resulting single quantum system is substantially lacking. Here we provide a first-principles theoretical tool to understand and design networks of linear modes integrated with embedded qubits. We utilize this theory to inform and analyze the experimental implementation of a qubit readout with an integrated three-mode nonreciprocal system. In doing so, we achieve excellent agreement between the experimental and theoretical qubit measurement and dephasing rates. We then theoretically analyze the same system operated as an integrated nonreciprocal amplifier, predicting high efficiency for reasonable experimental parameters.
format Preprint
id arxiv_https___arxiv_org_abs_2603_12312
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Qubit measurement and backaction in a multimode nonreciprocal system
Miller, B. T.
Orr, Lindsay
Metelmann, A.
Lecocq, F.
Quantum Physics
Mesoscale and Nanoscale Physics
High fidelity qubit readout is a cornerstone for quantum information protocols. In traditional superconducting qubit readout, a chain of microwave amplifiers and nonreciprocal components aid in detecting the qubit's state with tolerable added noise and backaction. However, the loss, size, and magnetic field of standard nonreciprocal components have sparked a decades-long search for more efficient and scalable alternatives. One prominent approach employs networks of parametrically coupled modes to achieve nonreciprocity. While this class of devices can be directly integrated with the qubit's readout cavity, current understanding of the resulting single quantum system is substantially lacking. Here we provide a first-principles theoretical tool to understand and design networks of linear modes integrated with embedded qubits. We utilize this theory to inform and analyze the experimental implementation of a qubit readout with an integrated three-mode nonreciprocal system. In doing so, we achieve excellent agreement between the experimental and theoretical qubit measurement and dephasing rates. We then theoretically analyze the same system operated as an integrated nonreciprocal amplifier, predicting high efficiency for reasonable experimental parameters.
title Qubit measurement and backaction in a multimode nonreciprocal system
topic Quantum Physics
Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2603.12312