Presentations -

スピン梯子系におけるトポロジカルエンタングルメントスワッピング

濱田瑞貴, 古川俊輔

日本物理学会2025年春季大会 (オンライン) , 

2025.03

, 

Oral presentation (general)

スピン梯子系におけるトポロジカルエンタングルメントスワッピング

濱田瑞貴, 古川俊輔

サスティナブル量子AI研究拠点第5回全体会議 (慶應義塾大学日吉キャンパス ) , 

2025.02

, 

Poster presentation

量子多体系における測定と場の理論

古川俊輔

場の理論の新しい計算方法2024 (東京大学駒場Ⅱキャンパス) , 

2024.12

, 

Public lecture, seminar, tutorial, course, or other speech

Investigation of topological phases and transitions via quantum control, quantum entanglement, and duality

Shunsuke Furukawa

The 4th ExU Annual Meeting of the Extreme Universe Collaboration (Nambu Yoichiro Hall, Osaka University) , 

2024.09

, 

Oral presentation (general)

Symmetry, topology, duality, chirality, and criticality in a spin-1/2 XXZ ladder with a four-spin interaction

M. Fontaine, K. Sugimoto, S. Furukawa

SUN2024 : SU(N) physics in quantum many-body systems: theory, experiment, and numerics (Sendai) , 

2024.07

, 

Poster presentation

Symmetry, topology, duality, chirality, and criticality in a spin-1/2 XXZ ladder with a four-spin interaction

M. Fontaine, K. Sugimoto, and S. Furukawa

SQAI-NCTS Workshop on Tensor Network and Quantum Embedding (Hongo Campus, University of Tokyo) , 

2024.03

, 

Poster presentation

Error-mitigated quantum computation of string order parameters across a topological phase transition

R. Kawase and S. Furukawa

SQAI-NCTS Workshop on Tensor Network and Quantum Embedding (Hongo Campus, University of Tokyo) , 

2024.03

, 

Poster presentation

Symmetry, topology, duality, chirality, and criticality in a spin-1/2 XXZ ladder with a four-spin interaction

M. Fontaine, K. Sugimoto, and S. Furukawa

サスティナブル量子AI研究拠点第3回全体会議 (東京大学本郷キャンパス山上会館) , 

2024.02

, 

Poster presentation

Error-mitigated quantum computation of string order parameters across a topological phase transition

R. Kawase and S. Furukawa

The 2nd young researchers' workshop of the Extreme Universe Collaboration (Shirahamaso, Shiga) , 

2024.02

, 

Oral presentation (general)

Symmetry, topology, duality, chirality, and criticality in a spin-1/2 XXZ ladder with a four-spin interaction

M. Fontaine, K. Sugimoto, and S. Furukawa

The 2nd young researchers' workshop of the Extreme Universe Collaboration (Shirahamaso, Shiga) , 

2024.02

, 

Oral presentation (general)

Symmetry, topology, duality, chirality, and criticality in a spin-1/2 XXZ ladder with a four-spin interaction

M. Fontaine, K. Sugimoto, and S. Furukawa

The 6th R-CCS International Symposium (Kobe International Conference Center) , 

2024.01

, 

Poster presentation

Error-mitigated quantum computation of string order parameters across a topological phase transition

R. Kawase and S. Furukawa

Computational Approaches to Quantum Many-Body Systems (SONIC CITY, Saitama) , 

2023.10

, 

Poster presentation

　View Summary

Recently, Smith et al. investigated a topological phase transition in a spin chain by measuring string order parameters on the IBM quantum computers [Phys. Rev. Research 4, L022020 (2022)]. The measured quantities showed appreciable reduction from theoretical values, owing to inherent noise in the devices. In this work, we reproduce their results in the noisy quantum circuit simulator (Qiskit Aer), and improve the accuracy of the measurements by exploiting the error mitigation technique called the virtual distillation. This technique enables an exponential error suppression given the preparation of n copies of the original circuits and some additional gates.

Vector chiral order and symmetry-protected topological phases in a spin-1/2 XXZ ladder with a four-spin interaction

M. Fontaine, K. Sugimoto, and S. Furukawa

Computational Approaches to Quantum Many-Body Systems (SONIC CITY, Saitama) , 

2023.10

, 

Poster presentation

　View Summary

We study the ground-state phase diagram of a spin-1/2 XXZ model with a chirality-chirality interaction (CCI) on a two-leg ladder. This model offers a minimal setup to study an interplay between spin and chirality degrees of freedom. The spin-chirality duality transformation allows us to relate the regimes of weak and strong CCIs. We perform numerical simulations to confirm the predicted phase structure and critical properties. We mainly used the iDMRG algorithm to determine the phase boundary, determine the nature of the transition, calculate the order parameter, and calculate topological indices associated with each topologically non-trivial phase.

Phase diagram of a spin-1/2 XXZ ladder with four-spin ring exchange

M. Fontaine, K. Sugimoto, and S. Furukawa

YIPQS Long-Term Workshop: Quantum Information, Quantum Matter, and Quantum Gravity (Kyoto University) , 

2023.09

-

2023.10

, 

Poster presentation

　View Summary

We study the ground-state phase diagram of a spin-1/2 XXZ model with four-spin ring exchange on a two-leg ladder. The spin-chirality duality transformation allows us to relate the regimes of weak and strong four-spin interactions. By applying the Abelian bosonization and the duality, we analyze a simplified model in which part of the four-spin interactions is removed, and predict a phase diagram that contains distinct gapped featureless and ordered phases. In particular, we predict Neel and vector chiral orders in the presence of easy-axis anisotropy, and two distinct symmetry protected topological phases in the presence of easy-plane anisotropy. We performed numerical simulations for both the simplified and full models to confirm the predicted phase structure. We demonstrated that the two SPT phases and a trivial phase are distinguished by topological indices in the presence of certain symmetries.

多成分ボース気体の量子ホール物理：対称性による保護と富化

古川俊輔

量子物理学・ナノサイエンス第367回セミナー, 

2023.07

, 

Public lecture, seminar, tutorial, course, or other speech

　View Summary

対称性が課されたもとで現れる多彩なトポロジカル相に注目が集まっている。対称性のもとで初めてトポロジカルな性質を獲得する相を「対称性で保護されたトポロジカル相」、もともと持っていたトポロジカルな性質が多様化されて現れる相を「対称性で多様化（富化）されたトポロジカル相」と呼ぶ。冷却原子系の持つ高い操作性を利用して、これらの相を実現できるかどうかは興味深い。冷却原子系においては、構成原子の多様さに加え、近年、磁場やスピン・軌道結合と同等の効果を光学的に誘起する人工ゲージ場の技術も発展している。ここでは、人工磁場中のn成分ボース気体の示す量子ホール状態についての我々の最近の研究を紹介し、対称性による保護と富化について議論する。

Phase diagram of a spin-1/2 XXZ ladder with four-spin ring exchange

M. Fontaine, K. Sugimoto, and S. Furukawa

Novel Quantum States in Condensed Matter 2022 (Kyoto University) , 

2022.10

-

2022.12

, 

Poster presentation

　View Summary

We study the ground-state phase diagram of a spin-1/2 XXZ model with a four-spin ring exchange on a two-leg ladder. The spin-chirality duality transformation allows us to relate the regimes of weak and strong four-spin interactions. By applying the Abelian bosonization and the duality, we analyze a simplified model in which part of the four-spin interactions is removed, and predict a phase diagram that contains eight distinct gapped phases. In particular, a vector chiral ordered phase and a twisted Haldane phase appear between the scalar chiral ordered phase and the dominant vector chirality phase in the regime of strong four-spin interactions. We perform numerical simulations for both the simplified and full models to confirm the predicted phase structure.

Ground-state phase diagram of a spin-1/2 frustrated XXZ ladder II

T. Ogino, R. Kaneko, S. Morita, S. Furukawa

日本物理学会2022年秋季大会 (オンライン開催) , 

2022.09

, 

Oral presentation (general)

Magnetic properties of volborthite determined by a coupled-trimer model

S. Furukawa and T. Momoi

International Workshop on Microscopic Properties of Quantum Materials (Hokkaido University) , 

2022.08

, 

Oral presentation (invited, special)

ボース気体およびスピン梯子におけるトポロジカル相：対称性による保護と富化

古川俊輔

物性基礎工学研究グループセミナー, 

2022.07

, 

Public lecture, seminar, tutorial, course, or other speech

Theory of volborthite based on a coupled trimer model

Shunsuke Furukawa

17th Quantum Spin Workshop (沖縄県那覇市ともかぜ振興会館およびオンライン) , 

2022.04

, 

Oral presentation (general)