Demonstration of subspace-search variational quantum eigensolver using photonic orbital angular momentum qudits

IF 9 1区物理与天体物理 Q1 PHYSICS, APPLIED

npj Quantum Information Pub Date : 2026-10-07 DOI:10.1038/s41534-026-01380-2

Kang-Min Hu,Myung-Hyun Sohn,Yong-Su Kim,Kwang Jo Lee,Hyun Woo Kim,Hyang-Tag Lim

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引用次数: 0

Abstract

Abstract Accurate excited-state energies are essential for interpreting fluorescence and photochemical processes, yet variational quantum eigensolvers (VQEs) on noisy intermediate-scale quantum (NISQ) hardware have largely been confined to ground states. Subspace-search VQE (SSVQE) offers a NISQ-friendly route to excited states without ancilla-based overlap measurements, however it has lacked an experimental demonstration since it requires the coherent preparation and manipulation of multiple orthogonal basis states under a shared variational unitary. Here we realize SSVQE on a photonic platform by encoding orthogonal qudit states in the orbital angular momentum of single photons and optimizing a shared variational circuit. We estimate excited-state energies for a four-dimensional HeH + molecule and an eight-dimensional Heisenberg chain, thereby demonstrating scalable excited state eigensolving in a high-dimensional Hilbert space. Our results establish photonic qudits as a resource-efficient pathway to excited-state quantum simulation.

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子空间搜索变分量子本征解的光子轨道角动量量子论证

精确的激发态能量对于解释荧光和光化学过程至关重要，但噪声中尺度量子（NISQ）硬件上的变分量子特征解（VQEs）在很大程度上局限于基态。子空间搜索VQE （SSVQE）提供了一种nisq友好的激发态路径，没有基于辅助的重叠测量，但是由于它需要在共享变分酉下的多个正交基态的相干制备和操作，因此缺乏实验证明。本文通过对单光子轨道角动量中的正交量子态进行编码，并优化共享变分电路，在光子平台上实现了SSVQE。我们估计了四维HeH +分子和八维Heisenberg链的激发态能量，从而证明了高维Hilbert空间中可扩展的激发态特征解。我们的结果建立了光子量子作为一个资源高效的途径激发态量子模拟。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

npj Quantum Information Computer Science-Computer Science (miscellaneous)

CiteScore

13.70

自引率

3.90%

发文量

130

审稿时长

29 weeks

期刊介绍： The scope of npj Quantum Information spans across all relevant disciplines, fields, approaches and levels and so considers outstanding work ranging from fundamental research to applications and technologies.