Exploring topology via momentum-selective tomography
Abstract
Identifying and measuring topological invariants remains a fundamental challenge due to the non-local nature of momentum eigenstates in real space. Established approaches based on Bloch oscillations, quantum walks, charge pumping and quench dynamics, typically fail to provide direct momentum-dependent geometric information of each Bloch state. Here, we propose a novel framework for implementing direct band-topology tomography via momentum-selective measurements, and experimentally demonstrate it on a superconducting processor featuring a highly connected coupling architecture. Utilizing a ``star-like" geometry in which an auxiliary probe couples to a one-dimensional topological chain with spatially modulated coupling strengths, we selectively address the desired momentum states of the chain. This approach enables the direct and robust extraction of the winding phase that contributes to the associated topological invariant. Leveraging non-local couplers bridged by long tantalum airbridges, we realize an extended Su-Schrieffer-Heeger (SSH) model and map its full topological phase diagram. Through a nested Fourier analysis over time and space, we directly extract the winding phase across Brillouin zone and resolve quantized winding numbers of ν={0,±1,2} characterized by phase winding {0, ± 2π,4π}. Our work establishes a versatile tool for probing topological characteristics and opens a new avenue for robust quantum computing architectures based on topological protection.
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BibTeX
@misc{huai2026exploring,
title = {{Exploring topology via momentum-selective tomography}},
author = {Sainan Huai and Ling Lin and Kunliang Bu and Tianqi Cai and Zhiwen Zong and Xiaopei Yang and Yuan Li and Yulei Ye and Zhenxing Zhang and Shengyu Zhang and Chaohong Lee},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.09673},
eprint = {2610.09673},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.09673},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Exploring topology via momentum-selective tomography
AU - Sainan Huai
AU - Ling Lin
AU - Kunliang Bu
AU - Tianqi Cai
AU - Zhiwen Zong
AU - Xiaopei Yang
AU - Yuan Li
AU - Yulei Ye
AU - Zhenxing Zhang
AU - Shengyu Zhang
AU - Chaohong Lee
PY - 2026
DA - 2026/10/07
PB - arXiv
DO - 10.48550/arxiv.2610.09673
UR - https://arxiv.org/abs/2610.09673
AB - Identifying and measuring topological invariants remains a fundamental challenge due to the non-local nature of momentum eigenstates in real space. Established approaches based on Bloch oscillations, quantum walks, charge pumping and quench dynamics, typically fail to provide direct momentum-dependent geometric information of each Bloch state. Here, we propose a novel framework for implementing direct band-topology tomography via momentum-selective measurements, and experimentally demonstrate it on a superconducting processor featuring a highly connected coupling architecture. Utilizing a ``star-like" geometry in which an auxiliary probe couples to a one-dimensional topological chain with spatially modulated coupling strengths, we selectively address the desired momentum states of the chain. This approach enables the direct and robust extraction of the winding phase that contributes to the associated topological invariant. Leveraging non-local couplers bridged by long tantalum airbridges, we realize an extended Su-Schrieffer-Heeger (SSH) model and map its full topological phase diagram. Through a nested Fourier analysis over time and space, we directly extract the winding phase across Brillouin zone and resolve quantized winding numbers of ν={0,±1,2} characterized by phase winding {0, ± 2π,4π}. Our work establishes a versatile tool for probing topological characteristics and opens a new avenue for robust quantum computing architectures based on topological protection.
ER -