2026-03-12 理化学研究所
図1 2次元量子多体系を実装する量子回路構成
heavy-hex格子状に結合した量子ビットを2次元量子スピン系として用い、単一量子ビットの回転と近接相互作用を周期的に繰り返す（左）。これにより周期駆動下の量子ダイナミクスを実機で観測する構成を取った（右）。
＜関連情報＞
- https://www.riken.jp/press/2026/20260312_1/index.html
- https://www.nature.com/articles/s41534-026-01193-3
デジタル量子コンピュータ上でクリーンな二次元離散時間結晶を明らかにする Unveiling clean two-dimensional discrete time crystals on a digital quantum computer
Kazuya Shinjo,Kazuhiro Seki,Tomonori Shirakawa,Rong-Yang Sun & Seiji Yunoki
npj Quantum Information Published:24 February 2026
DOI:https://doi.org/10.1038/s41534-026-01193-3
Abstract
Periodically driven (Floquet) many-body systems tend to absorb energy and approach an infinite-temperature state, yet can host emergent order such as discrete time crystals (DTCs). Here we realise a clean two-dimensional DTC and an incommensurately modulated DTC (IM-DTC) on the IBM Quantum Heron processor, a 133-qubit superconducting device with heavy-hexagonal connectivity, implementing a kicked Ising model and tracking magnetisation dynamics for up to 100 Floquet cycles. We observe robust period-doubling oscillations that persist over the accessible time window and are stable against perturbations of the transverse field, without invoking disorder-induced many-body localisation or high-frequency Floquet prethermalisation. Introducing a longitudinal field generates additional long-period amplitude modulations with frequencies incommensurate with the drive, realising an IM-DTC response. Comparison with state-vector and tensor-network simulations benchmarks the hardware and reveals regimes where entanglement growth makes classical simulation challenging, underscoring the utility of gate-based quantum processors for out-of-equilibrium dynamics in two dimensions.
