Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
平 義隆*; Yang, Y.*; 静間 俊行*; Omer, M.
Physical Review Research (Internet), 7(3), p.033130_1 - 033130_17, 2025/08
Highly polarized gamma rays with linear or circular polarization are essential light sources for nuclear and particle physics experiments, astronomical detector evaluations, and relativistic electron beam diagnostics. In this study, we demonstrate gamma-ray generation via Compton scattering with unique polarization states, termed axially symmetric polarization. To investigate this, we developed a polarimeter for Compton gamma-ray sources to measure their two-dimensional polarization distribution. We found two methods to generate gamma rays whose polarization axis follows the azimuthal direction. The first method exploits the inherent azimuthal polarization of gamma rays produced using a circularly polarized laser. In this configuration, the gamma rays along the central axis are circularly polarized, while the linear polarization components in the outer region of the beam cross section are aligned azimuthally. The second method utilizes azimuthal polarization that arises in the outer region of the beam due to the incoherent superposition of multiple linearly polarized gamma rays with varying polarization axes, generated by an axially symmetric polarized laser. Additionally, our calculations indicate the feasibility of generating gamma rays with polarization axes oriented along the radial direction. This radial polarization, observed near the beam axis, results from the incoherent superposition of second harmonic gamma rays produced through nonlinear interactions induced by an intense axially symmetric polarized laser.
中山 昌勲*; 御手洗 光祐*; Placidi, L.*; 杉本 貴則*; 藤井 啓祐*
Physical Review Research (Internet), 7(3), p.033048_1 - 033048_9, 2025/07
Quantum machine learning has the potential to computationally outperform classical machine learning, but it is not yet clear whether it will actually be valuable for practical problems. While some artificial scenarios have shown that certain quantum machine learning techniques may be advantageous compared to their classical counterpart, evidence does not yet suggest that quantum machine learning has surpassed conventional approaches in dealing with standard classical datasets, such as the MNIST dataset. In contrast, dealing with quantum data, such as quantum states or circuits, may be the task where we can benefit from quantum methods. Therefore, it is important to develop practically meaningful quantum datasets for which we expect quantum methods to be superior. In this paper, we propose a machine learning task that is likely to soon arise in the real world: clustering and classification of quantum circuits. We provide a dataset of quantum circuits optimized by the variational quantum eigensolver.
目黒 智成*; 小沢 耀弘*; 小林 浩二*; 荒木 康史; 野村 健太郎*
Physical Review Research (Internet), 7(2), p.L022065_1 - L022065_8, 2025/06
We theoretically find a topological spin-orbit torque (SOT) in the compensated ferrimagnetic Weyl semimetal Ti
MnAl. The topological SOT arises from all the occupied states, which is free from dissipation. However, it is negligible in metallic magnets and was not reported in Weyl semimetals. We show the enhancement of the topological SOT from the mixed Berry curvature around the Weyl points in TiMnAl. This finding provides a guiding principle for designing highly efficient SOT devices using the topological nature of ferrimagnetic Weyl semimetals.
Go, G.*; Goli, D. P.*; 江崎 蘭世; Tserkovnyak, Y.*; Kim, S. K.*
Physical Review Research (Internet), 7(2), p.L022066_1 - L022066_7, 2025/06
It remains an open question whether or not the scalar spin chirality itself can exhibit a Hall-type transport. In this work, we show that the answer is yes: The scalar spin chirality is Hall-transported in Kagome ferromagnets and antiferromagnets under an external bias, engendering a phenomenon which we dub the scalar spin chirality Nernst effect. Our findings call for the need to lift the conventional assumption that the scalar spin chirality is a static quantity in order to discover the active roles of the scalar spin chirality in transport properties.
and quadrupolar triple-q physics in a triangular lattice服部 一匡*; 石飛 尊之; 常次 宏一*
Physical Review Research (Internet), 6(4), p.L042068_1 - L042068_7, 2024/12
We numerically study orders of planer type 
quadrupoles on a triangular lattice with nearest-neighbor isotropic 
and anisotropic 
interactions. This type of quadrupoles possesses unique single-ion anisotropy proportional to a third order of the quadrupole moments. This provides an unconventional mechanism of triple-
orders which does not exist for the degrees of freedom with odd parity under time-reversal operation such as magnetic dipoles. In addition to several single- orders, we find various orders including incommensurate triple- quasi-long-range orders with orbital moire and a four-sublattice triple- partial order. Our Monte-Carlo simulations demonstrate that the phase transition to the latter triple- state belongs to the universality class of the critical line of the Ashkin-Teller model in two dimensions close to the four-state Potts class. These results indicate a possibility of realizing unique quadrupole textures in simple triangular systems.
片岡 佑太*; 春山 潤*; 杉野 修*; 志賀 基之
Physical Review Research (Internet), 6(4), p.043224_1 - 043224_12, 2024/12
パラジウム(111)表面における水素の量子拡散を、量子遷移状態理論とリングポリマー分子動力学の2種類の経路積分シミュレーションを用いて研究した。密度汎関数理論計算で学習させた人工ニューラルネットワークポテンシャル(NNP)を用いることで、多体Pd-H系の核量子効果を考慮した経路積分シミュレーションを第一原理計算の精度で行うことが可能となった。計算の結果、150-200K以下のHの拡散係数において、核量子効果に起因する明確な非アレニウス的振る舞いが見られた。
宮腰 祥平*; 杉本 貴則*; 白川 知功*; 柚木 清司*; 上田 宏*
Physical Review Research (Internet), 6(4), p.043318_1 - 043318_14, 2024/12
In recent years, quantum computing has evolved as an exciting frontier, with the development of numerous algorithms dedicated to constructing quantum circuits that adeptly represent quantum many-body states. However, this domain remains in its early stages and requires further refinement to better understand the effective construction of highly entangled quantum states within quantum circuits. Here, we demonstrate that quantum many-body states can be universally represented using a quantum circuit comprising multiqubit gates. Furthermore, we evaluate the efficiency of a quantum circuit constructed with two-qubit gates in quench dynamics for the transverse-field Ising model.
Catumba, G.*; 平口 敦基; Hou, W.-S.*; Jansen, K.*; Kao, Y.-J.*; David Lin, C.-J.*; Ramos, A.*; Sarkar, M.*
Physical Review Research (Internet), 6(4), p.043172_1 - 043172_12, 2024/11
様々な表現の物質場と結合するゲージ理論は、物理学の様々な分野で重要な役割を果たしている。最近、銅酸化物超伝導体の最適ドーピング近傍の興味深い擬ギャップ相のいくつかの側面が、発現したSU(2)ゲージ対称性によって説明できるかもしれないことが提案された。ホールドーピングによる転移付近では、4つの随伴スカラー場と結合した(2+1)次元SU(2)ゲージ理論を構築することができ、異なる破れた対称性を持つ様々な相が存在する豊かな相図を与える。我々は、ハイブリッドモンテカルロ法を用いて、ユークリッド格子上でこのモデルの相図を研究した。その結果、これまでの平均場の研究で予言されていたように、対称性が破れた複数の相が存在することがわかった。4点相互作用によって、摂動論の範囲ではこの理論のSU(2)ゲージ対称性はU(1)か
に分解される。さらに、我々はこの理論における閉じ込め-非閉じ込め転移を評価し、我々が研究した格子体積の範囲では、どちらの破れた相も非閉じ込め相であることを見いだした。しかしながら、ポリヤコフループの振る舞いには2つの相で顕著な違いがあることがわかった。
RhSi社本 真一; 山内 宏樹; 飯田 一樹*; 池内 和彦*; 金子 耕士; Chen, Y.-S.*; 矢野 真一郎*; Hsu, P.-T.*; Lee, M. K.*; Hall, A. E.*; et al.
Physical Review Research (Internet), 6(3), p.033303_1 - 033303_7, 2024/09
MnRhSiの磁気励起は少なくとも0.3から140meVに広がる。200Kでの非弾性散乱強度を積分することで、Mnサイト当たり約5
の磁気モーメントは、約5であることがわかった。一方で、長距離磁気秩序の磁気モーメントは4Kでわずか2.61であり、多くの部分が低温まで揺らいでいることがわかった。
signatures in two-dimensional cone beam interferometrySarenac, D.*; Gorbet, G.*; Clark, C. W.*; Cory, D. G.*; Ekinci, H.*; Henderson, M. E.*; Huber, M. G.*; Hussey, D. S.*; Kapahi, C.*; Kienzle, P. A.*; et al.
Physical Review Research (Internet), 6(3), p.L032054_1 - L032054_8, 2024/09
Neutron interferometry has played a distinctive role in fundamental science and characterization of materials. Moir neutron interferometers are candidate next-generation instruments: they offer microscopy-like magnification of the signal, enabling direct camera recording of interference patterns across the full neutron wavelength spectrum. Here we demonstrate the extension of phase-grating moir interferometry to two-dimensional geometries. Our measurements of phase topologies and gravitationally induced phase shifts are in good agreement with theory.
Josephson junctions and synchronized precession仲田 光樹; Zou, J.*; Klinovaja, J.*; Loss, D.*
Physical Review Research (Internet), 6(3), p.033207_1 - 033207_11, 2024/08
We uncover theoretically that a surprisingly rich dynamics can emerge in magnetic junctions due to intrinsic non-local damping, using analytical and numerical methods. In particular, under microwave pumping, we show that coherent spin precession in the right and left insulating ferromagnet (FM) of the junction becomes synchronized by non-local damping and thereby a magnonic analog of the Josephson junction emerges, where stands here for the relative precession phase of right and left FM in the stationary limit. Remarkably, decreases monotonically from 
to 
as the magnon-magnon interaction, arising from spin anisotropies, increases. Moreover, we also find a magnonic diode effect giving rise to rectification of magnon currents. Our predictions are readily testable with current device and measurement technologies at room temperatures.
Sarenac, D.*; Gorbet, G.*; Kapahi, C.*; Clark, C. W.*; Cory, D. G.*; Ekinci, H.*; Garrad, D. V.*; Henderson, M. E.*; Huber, M. G.*; Hussey, D.*; et al.
Physical Review Research (Internet), 6(2), p.023260_1 - 023260_15, 2024/06
Phase-grating moire interferometers (PGMIs) have emerged as promising candidates for the next generation of neutron interferometry, enabling the use of a polychromatic beam and manifesting interference patterns that can be directly imaged by existing neutron cameras. However, the modeling of the various PGMI configurations is limited to cumbersome numerical calculations and backward propagation models which often do not enable one to explore the setup parameters. Here we generalize the Fresnel scaling theorem to introduce a k-space model for PGMI setups illuminated by a cone beam, thus enabling an intuitive forward propagation model for a wide range of parameters and experimental setups.
BWO
Nagl, J.*; Flavi
n, D.*; Hayashida, S.*; Povarov, K. Y.*; Yan, M.*; 村井 直樹; 河村 聖子; Simutis, F.*; Hicken, T. J.*; Luetkens, H.*; et al.
Physical Review Research (Internet), 6(2), p.023267_1 - 023267_18, 2024/06
We investigate the rare-earth-based frustrated quantum antiferromagnet PrBWO, previously considered a spin-liquid candidate. Our experimental and theoretical analysis reveals that its ground state is better described as a quantum paramagnet, governed by an Ising model in a transverse field. While in-plane correlations exist, the dominant interactions form frustrated triangular spin tubes via competing ferro-antiferromagnetic bonds. The system's thermodynamic and dynamic properties are significantly influenced by hyperfine interactions and weak structural disorder.
土屋 旬*; 志賀 基之; 常行 真司*; Thompson, E. C.*
Physical Review Research (Internet), 6(2), p.023302_1 - 023302_6, 2024/06
第一原理経路積分分子動力学計算を用いて、水素原子の核量子効果が高圧・常温条件下での氷VIIの弾性に及ぼす影響を調べた。その結果、40GPa以上の圧力において、氷VIIの静的無秩序構造から動的無秩序構造への転移に対して核量子効果が寄与していることがわかった。この転移は弾性定数の不連続な増加によって特徴づけられる。第一原理分子動力学計算と第一原理経路積分分子動力学計算の比較から、核量子効果によって70GPa, 300Kにおける氷の弾性定数が約20%増加することが明らかになった。
中島 多朗*; 渡辺 真朗; 稲村 泰弘; 玉造 博夢; 他8名*
Physical Review Research (Internet), 6(2), p.023109_1 - 023109_9, 2024/05
We present proof-of-principle experiments of stroboscopic time-of-flight (TOF) neutron diffraction in long pulsed magnetic fields. By utilizing electric double-layer capacitors, we developed a long pulsed magnet for neutron diffraction measurements, which generates pulsed magnetic fields with the full widths at half maximum of more than 100 ms. The field variation is slow enough to be approximated as a steady field within the time scale of a polychromatic neutron pulse passing through a sample placed in a distance of the order of 10 m from the neutron source. This enables us to efficiently explore the reciprocal space using a wide range of neutron wavelength in high magnetic fields. We applied this technique to investigate field-induced magnetic phases in the triangular lattice antiferromagnets CuFe
Ga
O (x = 0, 0.035).
Rapp, L.*; 松岡 健之*; Firestein, K. L.*; 寒河江 大輔*; 羽原 英明*; 向井 啓一郎*; 田中 和夫*; Gamaly, E. G.*; 兒玉 了祐*; 瀬戸 雄介*; et al.
Physical Review Research (Internet), 6(2), p.023101_1 - 023101_18, 2024/04
固体表面に超相対論的強度のレーザーパルスを照射すると表面にプラズマが発生し、内部は超高圧状態になることが知られている。本研究ではシリコン単結晶に当該レーザーを照射し、内部に生成された高圧相の結晶構造分析をBL22XU(JAEA-BL)の応力・イメージングステーションの回折システムにより実施した。その結果、内部には体心、菱面体、六方晶、正方晶というシリコンが持つといわれている高圧相の存在が確認された。今後は、さらにデータの蓄積を図り、材料内部の構造、強度、機能性制御への発展を図っていきたいと考えている。
CoSi山内 宏樹; Sari, D. P.*; 安井 幸夫*; 坂倉 輝俊*; 木村 宏之*; 中尾 朗子*; 大原 高志; 本田 孝志*; 樹神 克明; 井川 直樹; et al.
Physical Review Research (Internet), 6(1), p.013144_1 - 013144_9, 2024/02
-Mn-type family alloys Mn
have three-dimensional antiferromagnetic (AFM) corner-shared triangular network. The antiferromagnet MnRhSi shows magnetic short-range order (SRO) over a wide temperature range of approximately 500 K above the N
el temperature 
= 190 K. MnCoSi has the smallest lattice parameter and the lowest in the family compounds. The quantum critical point (QCP) from AFM to the quantum paramagnetic state is expected near a cubic lattice parameter of 6.15 
of MnCoSi is only 140 K, quantum critical behavior is observed in MnCoSi as the enhancement of the electronic specific heat coefficient 
. We study how the magnetic SRO appears in MnCoSi by using neutron scattering, 
SR, and physical property measurements. The experimental results show that the neutron scattering intensity of the magnetic SRO does not change much regardless of the suppressed magnetic moment in the long-range magnetic ordered state compared to those of MnRhSi. The initial asymmetry drop ratio of SR above becomes small, and the magnetic SRO temperature 
is suppressed to 240 K. The results suggest that the MnCoSi is close to the QCP in the Mn system.
古府 麻衣子; 河村 聖子; 村井 直樹; 石井 梨恵子*; 平井 大悟郎*; 有馬 寛*; 舟越 賢一*
Physical Review Research (Internet), 6(1), p.013006_1 - 013006_9, 2024/01
We revisited spin dynamics in archetypical classical spin glass systems, such as CuMn (
, 0.034, and 0.067) dilute alloys and iron aluminosilicate glass using a modern neutron scattering spectrometer with high neutron flux. The former is crystalline, and the latter is amorphous, where their spin glass state is well separated from magnetically ordered phases. Bose-scaled localized magnetic excitations were observed in both compounds below the spin-freezing temperature (
). The spectrum exhibits a maximum at low energy and a broad tail on the high-energy side. The excitation energy tends to be higher for the material with a higher . Above the , the spectrum considerably changes with temperature, thereby indicating the emergence of the magnetic relaxation process. The magnetic excitation in the spin glass state has much in common with the boson peak in structural glasses. We consider that the Bose-scaled broad excitation peak is an elementary excitation inherent in disordered systems.
Visuri, A.-M.*; Mohan, J.*; 内野 瞬; Huang, M.-Z.*; Esslinger, T.*; Giamarchi, T.*
Physical Review Research (Internet), 5(3), p.033095_1 - 033095_11, 2023/08
粒子ロスのある量子ポイントコンタクト系のカレント・バイアス特性を研究する。Keldysh形式を採用し、チャンネルの透過率を変化させた場合のカレントを計算した。透過率の低い場合は、散逸により低バイアス領域でのカレントの増大、散逸に対する非単調性、輸送特性における新しい構造の出現が見られる。粒子ロスによる散逸の効果は、熱浴内の有限温度効果や非弾性散乱効果とは定性的に異なることがわかった。
中山 勝政*; 鈴木 渓
Physical Review Research (Internet), 5(2), p.L022054_1 - L022054_6, 2023/06
カシミール効果は、何らかの量子場から生じるゼロ点エネルギーが空間的な境界条件の存在によって変化することを起源とする量子現象であり、一粒子エネルギーが運動量について線形に増加するような「相対論的な」量子場(電磁場など)に関しては過去の理論的・実験的な研究によって一定の理解が得られている。一方で、分散関係が二次となる「非相対論的な」量子場も世の中には数多く存在するが、そのような系にもカシミール効果が存在するのか否かはそれほど自明でない。本論文では、様々な分散関係を持つ格子上の量子場のカシミール効果が存在(または消失)する条件について、理論的な考察を行った。特に、偶数次の分散関係を持つような量子場を調べたところ、二つの境界間の距離が長距離のときカシミール効果が消失するが、短距離のときにのみ特異的な「名残」が残る例(remnant Casimir effect)を発見した。このような現象の発見は、有限サイズの格子構造からなる量子系(例えば、3次元物質の薄膜、2次元物質のナノリボンやナノチューブ、1次元物質のナノワイヤなど)の物理量の理解や解釈に役立つことが期待される。また、一般に、質量(ギャップ)を持つ量子場では、質量の無い(ギャップレスな)量子場と比べてカシミール効果が弱くなることが知られているが、この性質について今回の発見を応用した再解釈を与える。
