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  "id": "oai:papers.qnfo.org:continuous-signal-processing-for-josephson-junction-readout",
  "slug": "continuous-signal-processing-for-josephson-junction-readout",
  "title": "Continuous Signal Processing for Josephson Junction Readout",
  "authors": [
    "Rowan Brad Quni-Gudzinas"
  ],
  "abstract": "The prevailing architecture of superconducting quantum information processing relies heavily on the Josephson junction, yet its dual role as both a qubit-defining non-linear inductor and a latching readout element creates a fundamental tension in measurement dynamics. While the former enables the isolation of a two-level subspace, the latter—often implemented as a bifurcation amplifier or latching comparator—imposes a premature digitization that destroys the continuous time-series of the quantum state evolution. This study reframes the quantum measurement problem through the lens of classical signal processing, positing that the “collapse” observed in standard readout schemes acts as a hardware-level quantization error isomorphic to a 1-bit Analog-to-Digital Converter (ADC). By simulating the information recovery rates of Traveling Wave Parametric Amplifiers (TWPAs) against traditional latching readouts, we demonstrate that continuous monitoring coupled with Kalman filtering can recover phase trajectories with a mean squared error (MSE) of 0.015, preserving the “verb” of quantum evolution. [...]",
  "abstract_markdown": "The prevailing architecture of superconducting quantum information processing relies heavily on the Josephson junction, yet its dual role as both a qubit-defining non-linear inductor and a latching readout element creates a fundamental tension in measurement dynamics. While the former enables the isolation of a two-level subspace, the latter—often implemented as a bifurcation amplifier or latching comparator—imposes a premature digitization that destroys the continuous time-series of the quantum state evolution. This study reframes the quantum measurement problem through the lens of classical signal processing, positing that the “collapse” observed in standard readout schemes acts as a hardware-level quantization error isomorphic to a 1-bit Analog-to-Digital Converter (ADC). By simulating the information recovery rates of Traveling Wave Parametric Amplifiers (TWPAs) against traditional latching readouts, we demonstrate that continuous monitoring coupled with Kalman filtering can recover phase trajectories with a mean squared error (MSE) of 0.015, preserving the “verb” of quantum evolution. [...]",
  "date": "2026-01-01",
  "first_published": "2026-01-01",
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        "name": "Rowan Brad Quni-Gudzinas",
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    "titles": [
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        "title": "Continuous Signal Processing for Josephson Junction Readout"
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        "description": "The prevailing architecture of superconducting quantum information processing relies heavily on the Josephson junction, yet its dual role as both a qubit-defining non-linear inductor and a latching readout element creates a fundamental tension in measurement dynamics. While the former enables the isolation of a two-level subspace, the latter—often implemented as a bifurcation amplifier or latching comparator—imposes a premature digitization that destroys the continuous time-series of the quantum state evolution. This study reframes the quantum measurement problem through the lens of classical signal processing, positing that the “collapse” observed in standard readout schemes acts as a hardware-level quantization error isomorphic to a 1-bit Analog-to-Digital Converter (ADC). By simulating the information recovery rates of Traveling Wave Parametric Amplifiers (TWPAs) against traditional latching readouts, we demonstrate that continuous monitoring coupled with Kalman filtering can recover phase trajectories with a mean squared error (MSE) of 0.015, preserving the “verb” of quantum evolution. [...]",
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