Normal-ordered perturbative expansion for matter systems interacting with continuous-mode quantum photon fields
Abstract
We develop a normal-ordered perturbative expansion method to compute the reduced dynamics of a matter system interacting with a general continuous-mode photon field state. In this expansion, all field correlation functions are automatically normal-ordered, while the free evolution is modified by spontaneous emission. Our normal-ordered expansion elucidates the physical meaning of non-normal-ordered correlation terms in the conventional expansion. Furthermore, under intermediate coupling strengths, the normal-ordered expansion converges significantly faster than the conventional expansion, allowing one to extend the applicability of perturbative expansion to much larger matter-light coupling strengths. Interestingly, given an m-photon Fock state input, the normal-ordered expansion truncates exactly at the 2m-th order. For special classes of input states, we show the normal-ordered expansion is consistent with the corresponding master equations. We demonstrate the normal-ordered expansion numerically for a two-level system interacting with coherent state, m-photon Fock state, and cat state inputs.
Related
- Scalable Density-Based Bootstrap Embedding with Perturbative Triples for Large Molecular Systems
- Multi-criteria assessments (MCA) of crop-livestock systems interacting through the grazing of flocks of sheep
- Decarbonizing isolated power systems: The role of renewable sources, storage and grid expansion
- Continuous crystallization of pharmaceutical compounds in mixed suspension mixed product removal systems
- Designing nonlinear perturbative metamaterials that compute
BibTeX
@misc{ko2026normalordered,
title = {{Normal-ordered perturbative expansion for matter systems interacting with continuous-mode quantum photon fields}},
author = {Liwen Ko and Robert L. Cook and K. Birgitta Whaley},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.38576},
eprint = {2609.38576},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.38576},
}
RIS
TY - UNPB
TI - Normal-ordered perturbative expansion for matter systems interacting with continuous-mode quantum photon fields
AU - Liwen Ko
AU - Robert L. Cook
AU - K. Birgitta Whaley
PY - 2026
DA - 2026/09/29
PB - arXiv
DO - 10.48550/arxiv.2609.38576
UR - https://arxiv.org/abs/2609.38576
AB - We develop a normal-ordered perturbative expansion method to compute the reduced dynamics of a matter system interacting with a general continuous-mode photon field state. In this expansion, all field correlation functions are automatically normal-ordered, while the free evolution is modified by spontaneous emission. Our normal-ordered expansion elucidates the physical meaning of non-normal-ordered correlation terms in the conventional expansion. Furthermore, under intermediate coupling strengths, the normal-ordered expansion converges significantly faster than the conventional expansion, allowing one to extend the applicability of perturbative expansion to much larger matter-light coupling strengths. Interestingly, given an m-photon Fock state input, the normal-ordered expansion truncates exactly at the 2m-th order. For special classes of input states, we show the normal-ordered expansion is consistent with the corresponding master equations. We demonstrate the normal-ordered expansion numerically for a two-level system interacting with coherent state, m-photon Fock state, and cat state inputs.
ER -