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 QuantumFCSjl, 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.
Related
- Nonequilibrium full counting statistics of multicomponent strongly-interacting quantum gases with defects
- The Transient Counting Statistics of Autonomous Quantum Clocks
- Quantum Dynamics of Full Counting Statistics in Fermionic Lattices with Localized Gain
- Exact Haar Statistics of Planar k-Purity in Multipartite Quantum Systems
- Efficient adaptive control strategy for multi-parameter quantum metrology in two-dimensional systems
BibTeX
@misc{daniel2026quantumfcsjl,
title = {{QuantumFCS.jl: Efficient Full-Counting Statistics for Open Quantum Systems}},
author = {Aaron Daniel and Marcelo Janovitch},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2607.24429},
eprint = {2607.24429},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.24429},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - QuantumFCS.jl: Efficient Full-Counting Statistics for Open Quantum Systems
AU - Aaron Daniel
AU - Marcelo Janovitch
PY - 2026
DA - 2026/09/01
PB - arXiv
DO - 10.48550/arxiv.2607.24429
UR - https://arxiv.org/abs/2607.24429
AB - Full-counting statistics (FCS) provides a systematic framework for characterising current fluctuations in quantum transport, quantum optics, and open quantum systems. We introduce QuantumFCSjl, 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.
ER -