Perfect state transfer under matrix powers: parity and spectral arithmetic
Abstract
For a real symmetric matrix H and distinct vertices a,b, we classify exponents k for which Hk has perfect state transfer (PST) from a to b. If their supported eigenvalues are integer multiples of a common positive number, every odd exponent reduces to H and every positive even exponent reduces to H2. We determine the minimum transfer times using a greatest common divisor of supported spectral differences. For rational symmetric matrices, symmetry of the source vertex support about zero implies the odd-power equivalence without a commensurability assumption; this includes all bipartite graphs. If the source vertex supports zero, PST under one positive even power implies PST under every positive even power. For a symmetric three-point quadratic spectrum whose outer projection signs agree and differ from the central sign, a nonzero rational shift leaves exactly one PST exponent. We classify all adjacency powers of hypercubes, cycles, and Johnson graphs, and all adjacency squares of paths. In particular, the adjacency matrix of P7 has PST from vertex $2$ to vertex $6$ only at exponent $2$.
Related
- Arithmetic triangular structures in the transfer-matrix of finite Kronig-Penney models
- Spectral width and polynomial degree in perfect state transfer
- Local obstructions and certified computations for perfect powers in power sums
- ARITHMETIC UNLIKELY INTERSECTIONS IN POWERS OF THE MULTIPLICATIVE GROUP
- Perfect powers with few digits and S-unit coefficients
BibTeX
@misc{song2026perfect,
title = {{Perfect state transfer under matrix powers: parity and spectral arithmetic}},
author = {Xingkun Song},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.18018},
eprint = {2609.18018},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.18018},
}
RIS
TY - UNPB
TI - Perfect state transfer under matrix powers: parity and spectral arithmetic
AU - Xingkun Song
PY - 2026
DA - 2026/09/16
PB - arXiv
DO - 10.48550/arxiv.2609.18018
UR - https://arxiv.org/abs/2609.18018
AB - For a real symmetric matrix H and distinct vertices a,b, we classify exponents k for which H^k has perfect state transfer (PST) from a to b. If their supported eigenvalues are integer multiples of a common positive number, every odd exponent reduces to H and every positive even exponent reduces to H^2. We determine the minimum transfer times using a greatest common divisor of supported spectral differences. For rational symmetric matrices, symmetry of the source vertex support about zero implies the odd-power equivalence without a commensurability assumption; this includes all bipartite graphs. If the source vertex supports zero, PST under one positive even power implies PST under every positive even power. For a symmetric three-point quadratic spectrum whose outer projection signs agree and differ from the central sign, a nonzero rational shift leaves exactly one PST exponent. We classify all adjacency powers of hypercubes, cycles, and Johnson graphs, and all adjacency squares of paths. In particular, the adjacency matrix of P_7 has PST from vertex $2$ to vertex $6$ only at exponent $2$.
ER -