ハイブリッド量子系における非線形現象

2020 年度 実績報告書

• 研究課題/領域番号: 19H00662
• 研究機関: 日本電信電話株式会社NTT物性科学基礎研究所
• 研究代表者: Munro William 日本電信電話株式会社NTT物性科学基礎研究所, 量子科学イノベーション研究部, 上席特別研究員 (50599553)
• 研究分担者: 根本 香絵 国立情報学研究所, 情報学プリンシプル研究系, 教授 (80370104)
• 研究期間 (年度): 2019-04-01 – 2023-03-31
• キーワード: Hybrid Quantum Systems / Nonlinear phenomena / Superradiance / Quantum Thermodynamics / Quantum Simulation / Quantum Correlations / Collective relaxation / Quantum Information

研究実績の概要

Beginning the second year of the project our simulation code was implemented on a 200 nodes cluster with 3 TB RAM. This allowed larger scale simulation over longer time scales. Enhanced simulations of the dynamics of a double domain nuclear spin ensemble coupled to the Nambu-Goldstone boson were undertaken with realistic parameters. The simulation reproduced the experimental observed data. Our work opens up the possibility for the exploration of novel collective behavior in solid state systems where the natural energies associated with those spins are much less than the thermal energy (published in PRB Letters).

Next, we explored a quantum battery protocol using super radiance and absorption. This protocol using dark states to achieve both super extensive capacity and power density, with spins coupled to a reservoir. Quantum correlations are essential for this to be achieved. Further, the power density scales with the number of spins N in the battery. While connected to the charger, the charged state of the battery is a steady state, stabilized through quantum interference in the open system (published in Phys. Rev. Applied).

We also continued our exploration of HQS for quantum simulation. We used our simulator to explore discrete time crystals, a novel state of matter, emerging in periodically driven quantum systems (ensembles of qubits). We found that a small amount of disorder results in network evolution that exhibits an emergent preferential attachment mechanism related to the existence of scale-free networks. This work was published in Science Advances.

現在までの達成度 (区分)

2: おおむね順調に進展している

理由

The project is on track with the 2nd-year activities completed.
We have implemented our HQS on a high performance cluster with a moving basis set to reduce the computational problem size. Further we have had the simulator exploring superradiance over time scales ranging from ns to mins in two distinct physical arrangements; namely electron spin ensembles coupled to superconducting circuits and nuclear spin ensemble coupled to the Nambu-Goldstone boson in GaAs semiconductors.
We also showed that superradiance / superabsorption in coupled HQS enables ultrafast charging of the second ensemble and slow discharge. This should allow one to realize a quantum battery.
Last all Milestones were completed. Presentations at major international conferences was delayed due to COVID.

今後の研究の推進方策

Our focus this year will be:
A. Exploring multi ensembles coupled to single/multiple baths to determine whether superradiance can enhance energy transport through a network. The concept is that one ensemble superradiantly emits while another super absorbs. This should allow energy transport faster than through normal relaxation. However, can we design the process to move energy along a chain of nodes.
B. We will be to continue our exploration of driven HQS to understand their potential for quantum simulation tasks.
[Milestone 6] Determine the potential of this tunable hybrid system to simulate superradiance effects in other physical system (Month 36)
[Milestone 7] Extend our investigation to include multiple ensembles coupled to the bath (Month 36)

研究成果

• [雑誌論文] Chimera Time-Crystalline Order in Quantum Spin Networks (2021)
  • 著者名/発表者名: Sakurai A.、Bastidas V. M.、Munro W. J.、Nemoto Kae
  • 雑誌名: Physical Review Letters 巻: 126 ページ: 120606 (1-6)
  • DOI: 10.1103/PhysRevLett.126.120606
  • 査読あり
• [雑誌論文] Quantum metamorphism (2020)
  • 著者名/発表者名: Bastidas V. M.、Estarellas M. P.、Osada T.、Nemoto Kae、Munro W. J.
  • 雑誌名: Physical Review B 巻: 102 ページ: 224307 (1-10)
  • DOI: 10.1103/PhysRevB.102.224307
  • 査読あり
• [雑誌論文] Ergodic-Localized Junctions in a Periodically Driven Spin Chain (2020)
  • 著者名/発表者名: Zha Chen、Bastidas V.M.、Gong Ming、Wu Yulin、Rong Hao、Yang Rui、Ye Yangsen、Li Shaowei、Zhu Qingling、Wang Shiyu、Zhao Youwei、Liang Futian、Lin Jin、Xu Yu、Peng Cheng-Zhi、Schmiedmayer J.、Nemoto Kae、Deng Hui、Munro W.J.、Zhu Xiaobo、Pan Jian-Wei
  • 雑誌名: Physical Review Letters 巻: 125 ページ: 170503 (1-6)
  • DOI: 10.1103/PhysRevLett.125.170503
  • 査読あり / 国際共著
• [雑誌論文] Simulating complex quantum networks with time crystals (2020)
  • 著者名/発表者名: Estarellas M. P.、Osada T.、Bastidas V. M.、Renoust B.、Sanaka K.、Munro W. J.、Nemoto K.
  • 雑誌名: Science Advances 巻: 6 ページ: aay8892 (1-8)
  • DOI: 10.1126/sciadv.aay8892
  • 査読あり / オープンアクセス
• [雑誌論文] Using Dark States to Charge and Stabilize Open Quantum Batteries (2020)
  • 著者名/発表者名: Quach James Q.、Munro William J.
  • 雑誌名: Physical Review Applied 巻: 14 ページ: 024092 (1-9)
  • DOI: 10.1103/PhysRevApplied.14.024092
  • 査読あり / 国際共著
• [雑誌論文] Dissipative nonequilibrium synchronization of topological edge states via self-oscillation (2020)
  • 著者名/発表者名: Waechtler C. W.、Bastidas V. M.、Schaller G.、Munro W. J.
  • 雑誌名: Physical Review B 巻: 102 ページ: 014309 (1-9)
  • DOI: 10.1103/PhysRevB.102.014309
  • 査読あり / 国際共著
• [学会発表] Quantum simulation with periodically-driven superconducting quantum processors (2021)
  • 著者名/発表者名: V. M. Bastidas, Chen Zha, Ming Gong, Yulin Wu, Hao Rong, Rui Yang, Yangsen Ye, Shaowei Li, Qingling Zhu, Shiyu Wang, Youwei Zhao, Futian Liang, Jin Lin, Yu Xu, Cheng-Zhi Peng, Jorg Schmiedmayer, Kae Nemoto, Hui Deng, W. J. Munro, Xiaobo Zhu and Jian-Wei Pan
  • 学会等名: The symposium on Quantum Computing: Status and Outlook at the 68th JSAP Meeting 2021, Online conference, Japan, March 16-19 (2021)
  • 招待講演
• [学会発表] Universal Quantum Simulation with a One-dimensional Quantum Processor (2020)
  • 著者名/発表者名: Kae Nemoto
  • 学会等名: OSA Quantum 2.0 Conference, Online Conference, USA, September 14 - 17 (2020)
  • 国際学会 / 招待講演
• [学会発表] Chimera-like Discrete Time Crystal in quantum spin networks (2020)
  • 著者名/発表者名: Akitada Sakurai, Victor M. Bastidas, William. J Munro and Kae Nemoto
  • 学会等名: Freiburg-Asia Mini-Workshop, Online conference, Germany, September 19 - 22 (2020)
• [学会発表] Chimera-like Discrete Time Crystal in quantum spin networks (2020)
  • 著者名/発表者名: Akitada Sakurai, Victor M. Bastidas, William. J Munro and Kae Nemoto
  • 学会等名: Fundamental science & quantum technologies using atomic systems .(FSQT2020), Online conference, India, September 28 - October 1 (2020)