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Computationally Pumped Bath Noise, Version 2: A Multi-Scale, History-Dependent Noise Model for Quantum Circuit Simulation in PKTron

Dr. Zuhair Ahmed

Published in SCIENTRA on 7 October 2026. Previously appeared in Zenado.

Abstract

PKTron is an open-source, PyPI-distributed quantum circuit simulator aimed at education and low-resource research settings. This paper documents Computationally Pumped Bath Noise version 2 (CPBN v2), a noise subsystem added in PKTron 13.0.0 that models decoherence as the output of one or more classical “bath” processes whose instantaneous error-pump strength depends on recent circuit activity rather than being fixed in advance. We describe the governing update rule, the three execution paths through which CPBN v2 is exposed — exact shot-sampled Pauli trajectories, Pauli-frame sampling for Clifford circuits, and a closed-form combined-channel approximation — and the statistical and hardware-comparison tooling that accompanies it. We report internal consistency checks (the combined-channel path reproduces trajectory sampling to within 1×10⁻¹⁰, and a bounded-parameter case reproduces the prior PKTron 12 noise model exactly) and single-machine runtime benchmarks across three backends. We are explicit about what this work does and does not claim: CPBN v2 is a phenomenological, software-level noise model intended for simulation, education, and algorithm-development use; it has not been validated against physical device noise spectra, and the benchmark numbers are sandbox measurements on one CPU, not a claim of general performance. We discuss the model's assumptions, limitations, and appropriate scope of use.

Keywords

quantum circuit simulation; non-Markovian noise; open quantum systems; Pauli channels; Clifford simulation; Pauli-frame sampling; open-source scientific software

References

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