Qubit-environment entanglement in pure dephasing dynamics for mixed initial states
Abstract
Decoherence of qubits is one main limitation in quantum information processing, where the qubits themselves can be mixed because of decoherence and additional decoherence may generated through interactions with a bath. Here, we present a complete study of qubit-environment entanglement in the case of interactions that lead to pure dephasing of the qubit by allowing the initial state of the qubit to be mixed, exceeding previous restrictions. We find that the criteria for separability that hold for pure initial states of the qubit are reduced to witness status. Yet, the evolution of the witnesses reflects the array of features that entanglement can exhibit in the mixed case but are forbidden in the pure-qubit case. Most notably, this includes sudden birth of entanglement as the initial phase of the evolution is typically separable. Moreover, there is a stark numerical advantage to the study of entanglement for large environments when using the witness rather than the traditional measures available. We include the study of entanglement generated between a spin qubit and a sparse spin environment to illustrate the peculiarities of the evolution of entanglement in this case, as well as to emphasize the level of reliability of the entanglement witness.
Related
- Basis-Independent Coherence Dynamics of Tripartite States under Pure Dephasing
- Entanglement Growth from Structured Initial States in Many-Body Localized Systems
- Resonance-Protected Pointer States: Stationary-Phase Analysis of Entanglement in an Environment-Coupled Two-Spin System
- Initial-State Preparation for Strongly Correlated Molecules from Matrix Product States: Benchmarking and Environment-Aware Divide-and-Conquer Compilation
- Entanglement dynamics of accelerated atoms with environment-induced interactions
BibTeX
@misc{strzalka2026qubitenvironment,
title = {{Qubit-environment entanglement in pure dephasing dynamics for mixed initial states}},
author = {Małgorzata Strzałka and Nico Peters and Laura Ares and Jan Sperling and Katarzyna Roszak},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.36936},
eprint = {2610.36936},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.36936},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Qubit-environment entanglement in pure dephasing dynamics for mixed initial states
AU - Małgorzata Strzałka
AU - Nico Peters
AU - Laura Ares
AU - Jan Sperling
AU - Katarzyna Roszak
PY - 2026
DA - 2026/10/27
PB - arXiv
DO - 10.48550/arxiv.2610.36936
UR - https://arxiv.org/abs/2610.36936
AB - Decoherence of qubits is one main limitation in quantum information processing, where the qubits themselves can be mixed because of decoherence and additional decoherence may generated through interactions with a bath. Here, we present a complete study of qubit-environment entanglement in the case of interactions that lead to pure dephasing of the qubit by allowing the initial state of the qubit to be mixed, exceeding previous restrictions. We find that the criteria for separability that hold for pure initial states of the qubit are reduced to witness status. Yet, the evolution of the witnesses reflects the array of features that entanglement can exhibit in the mixed case but are forbidden in the pure-qubit case. Most notably, this includes sudden birth of entanglement as the initial phase of the evolution is typically separable. Moreover, there is a stark numerical advantage to the study of entanglement for large environments when using the witness rather than the traditional measures available. We include the study of entanglement generated between a spin qubit and a sparse spin environment to illustrate the peculiarities of the evolution of entanglement in this case, as well as to emphasize the level of reliability of the entanglement witness.
ER -