QuantumFCS.jl: Efficient Full-Counting Statistics for Open Quantum Systems

Title:QuantumFCS.jl: Efficient Full-Counting Statistics for Open Quantum Systems

Abstract:Full-counting statistics (FCS) provides a systematic framework for characterising current fluctuations in quantum transport, quantum optics, and open quantum systems. We introduce this http URL, an open-source Julia package for efficient and flexible numerical FCS calculations. The package defines currents through monitored jump operators and weights, allowing particle, electric, and heat currents to be treated within the same workflow. It implements a recursive cumulant algorithm with dense, sparse, and iterative solver backends, making it suitable for models that are challenging for direct dense methods. We demonstrate the package on photon counting in a driven-dissipative Jaynes-Cummings system near the blockade-breakdown phase transition and on heat-current fluctuations in a non-linear circuit-QED heat engine. These examples show how higher cumulants reveal intermittency between bright and dim emission, antibunching, and provide probes of thermodynamic uncertainty relations. Benchmarks against an existing FCS implementation show substantial speed-ups.

arXiv:2607.24429 [quant-ph]

(or arXiv:2607.24429v1 [quant-ph] for this version)

https://doi.org/10.48550/arXiv.2607.24429 Focus to learn more arXiv-issued DOI via DataCite (pending registration)

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