Peer-reviewedCC BY 4.0Quantum
A Counterexample to the Optimality Conjecture in Convex Quantum Channel Optimization
- 1School of Mathematical Sciences, University of Electronic Science and Technology of China
- 2State Key Laboratory of Mathematical Sciences, Academy of Mathematics and Systems Science, Chinese Academy of Sciences
Abstract
This paper presents a counterexample to the optimality conjecture for the trace distance based optimal state transformation problem proposed by Coutts et al. [Quantum 5, 448 (2021)]. The conjecture posits that for the trace distance based optimal state transformation problem, applying the sign function to the error matrix uniquely determines a dual certificate for every optimal solution. By constructing a counterexample in 2-dimensional Hilbert spaces, we disprove this conjecture.
Related
- A counterexample to the quantum Hedetniemi conjecture
- On the completeness of gravitational pp-wave spacetimes: A counterexample to the {Ehlers--Kundt} conjecture
- Rank-Dependent Error Bounds and Near-Optimality in Quantum Control via Hierarchical Tucker Surrogates
- Conditions for Global Optimality in Quantum Arimoto-Blahut Algorithms
- Comparing classical and quantum QUBO solvers: optimality, trajectory diagnostics, and limits of solver selection
BibTeX
@article{yang2026counterexample,
title = {{A Counterexample to the Optimality Conjecture in Convex Quantum Channel Optimization}},
author = {Jianting Yang},
journal = {Quantum},
year = {2026},
month = oct,
doi = {10.22331/q-2026-10-28-2253},
url = {https://quantum-journal.org/papers/q-2026-10-28-2253/},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - A Counterexample to the Optimality Conjecture in Convex Quantum Channel Optimization
AU - Jianting Yang
PY - 2026
DA - 2026/10/28
JO - Quantum
DO - 10.22331/q-2026-10-28-2253
UR - https://quantum-journal.org/papers/q-2026-10-28-2253/
AB - This paper presents a counterexample to the optimality conjecture for the trace distance based optimal state transformation problem proposed by Coutts et al. [Quantum 5, 448 (2021)]. The conjecture posits that for the trace distance based optimal state transformation problem, applying the sign function to the error matrix uniquely determines a dual certificate for every optimal solution. By constructing a counterexample in 2-dimensional Hilbert spaces, we disprove this conjecture.
SN - 2521-327X
ER -