In this study, we evaluate spin interferometry with high-frequency magnetic fields using a continuous neutron beam. We derive an analytical formula for neutron spin interference with oscillating magnetic fields parallel to the quantization axis. The formula indicates that the phase of the interference pattern was not shifted but its amplitude, or visibility, was reduced by the oscillating magnetic fields. The experiment at MINE2 effectively reproduced this phenomenon and the degree of the amplitude reduction also followed the formula. Monochromatic neutron beams with long wavelengths such as 8.8 Å at MINE2 make it easy to polarize the beams to conduct high-visibility spin interferometric experiments. As a result, MINE2 is useful for testing new aspects of phenomena based on neutron spin optics.
{"title":"A Study of Oscillating Magnetic Fields with Neutron Spin Interferometry","authors":"Takaya Suzuki, Ryuto Fujitani, Seiji Tasaki, Masahiro Hino, Masaaki Kitaguchi, Tatsuro Oda, Riichiro Nakamura","doi":"10.7566/jpsj.93.091008","DOIUrl":"https://doi.org/10.7566/jpsj.93.091008","url":null,"abstract":"In this study, we evaluate spin interferometry with high-frequency magnetic fields using a continuous neutron beam. We derive an analytical formula for neutron spin interference with oscillating magnetic fields parallel to the quantization axis. The formula indicates that the phase of the interference pattern was not shifted but its amplitude, or visibility, was reduced by the oscillating magnetic fields. The experiment at MINE2 effectively reproduced this phenomenon and the degree of the amplitude reduction also followed the formula. Monochromatic neutron beams with long wavelengths such as 8.8 Å at MINE2 make it easy to polarize the beams to conduct high-visibility spin interferometric experiments. As a result, MINE2 is useful for testing new aspects of phenomena based on neutron spin optics.","PeriodicalId":17304,"journal":{"name":"Journal of the Physical Society of Japan","volume":"64 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141173470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A critical endpoint appears when a DC electric field is applied to a nematic liquid crystal with positive dielectric anisotropy. We have investigated the soft mode behavior near the critical endpoint of the nematic liquid crystal 8CB by dielectric spectroscopy while finely varying the temperature and DC electric field around it. Using an expression for the dielectric constant derived from the Landau–de Gennes theory, we obtained the relaxation strength and frequency for the soft mode from dielectric dispersions. An increase in relaxation strength and a decrease in relaxation frequency were observed as the critical endpoint was approached, which was expected from the theory.
{"title":"Soft Mode Behavior Near the Critical Endpoint of a Nematic Liquid Crystal with Positive Dielectric Anisotropy","authors":"Yoshinori Takikawa, Taro Tamehiro, Makoto Iwata, Hiroshi Orihara","doi":"10.7566/jpsj.93.064004","DOIUrl":"https://doi.org/10.7566/jpsj.93.064004","url":null,"abstract":"A critical endpoint appears when a DC electric field is applied to a nematic liquid crystal with positive dielectric anisotropy. We have investigated the soft mode behavior near the critical endpoint of the nematic liquid crystal 8CB by dielectric spectroscopy while finely varying the temperature and DC electric field around it. Using an expression for the dielectric constant derived from the Landau–de Gennes theory, we obtained the relaxation strength and frequency for the soft mode from dielectric dispersions. An increase in relaxation strength and a decrease in relaxation frequency were observed as the critical endpoint was approached, which was expected from the theory.","PeriodicalId":17304,"journal":{"name":"Journal of the Physical Society of Japan","volume":"2 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141166749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A theory of strong coupling superconductivity in uranium compounds has been developed, based on electron–electron interaction through magnetic fluctuations described by frequency-dependent magnetic susceptibility. The magnetic field dependence of the electron effective mass is expressed through the field dependence of the magnetic susceptibility components. It is shown that the intensity of triplet pairing, and hence the critical temperature of the transition to the superconducting state, is also determined by the field-dependent susceptibility. The results are discussed in relation to the properties of ferromagnetic uranium compounds URhGe and UCoGe, as well as the recently discovered UTe2.
{"title":"Effective Mass and Field-Reinforced Superconductivity in Uranium Compounds","authors":"Vladimir P. Mineev","doi":"10.7566/jpsj.93.064705","DOIUrl":"https://doi.org/10.7566/jpsj.93.064705","url":null,"abstract":"A theory of strong coupling superconductivity in uranium compounds has been developed, based on electron–electron interaction through magnetic fluctuations described by frequency-dependent magnetic susceptibility. The magnetic field dependence of the electron effective mass is expressed through the field dependence of the magnetic susceptibility components. It is shown that the intensity of triplet pairing, and hence the critical temperature of the transition to the superconducting state, is also determined by the field-dependent susceptibility. The results are discussed in relation to the properties of ferromagnetic uranium compounds URhGe and UCoGe, as well as the recently discovered UTe<sub>2</sub>.","PeriodicalId":17304,"journal":{"name":"Journal of the Physical Society of Japan","volume":"27 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141166751","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The decay of quantum complex systems through a potential barrier is often described with transition-state theory, also known as RRKM theory in chemistry. Here we derive the basic formula for transition-state theory based on a generic Hamiltonian as might be constructed in a configuration-interaction basis. Two reservoirs of random Hamiltonians from Gaussian orthogonal ensembles are coupled to intermediate states representing the transition states at a barrier. Under the condition that the decay of the reservoirs to open channels is large, an analytic formula for reaction rates is derived. The transition states act as independent Breit–Wigner resonances which contribute additively to the total transition probability, as is well known for electronic conductance through resonant tunneling states. It is also found that the transition probability is independent of the decay properties of the states in the second reservoir over a wide range of decay widths.
{"title":"Microscopic Derivation of Transition-state Theory for Complex Quantum Systems","authors":"Kouichi Hagino, George F. Bertsch","doi":"10.7566/jpsj.93.064003","DOIUrl":"https://doi.org/10.7566/jpsj.93.064003","url":null,"abstract":"The decay of quantum complex systems through a potential barrier is often described with transition-state theory, also known as RRKM theory in chemistry. Here we derive the basic formula for transition-state theory based on a generic Hamiltonian as might be constructed in a configuration-interaction basis. Two reservoirs of random Hamiltonians from Gaussian orthogonal ensembles are coupled to intermediate states representing the transition states at a barrier. Under the condition that the decay of the reservoirs to open channels is large, an analytic formula for reaction rates is derived. The transition states act as independent Breit–Wigner resonances which contribute additively to the total transition probability, as is well known for electronic conductance through resonant tunneling states. It is also found that the transition probability is independent of the decay properties of the states in the second reservoir over a wide range of decay widths.","PeriodicalId":17304,"journal":{"name":"Journal of the Physical Society of Japan","volume":"52 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141146519","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Equilibrium flows of impure plasmas in magnetically confined plasmas of arbitrary aspect ratio are calculated by neoclassical theory. For magnetically confined plasmas with the inverse aspect ratio approaching unity from below, the variation of the magnetic field strength along the field becomes large and as a consequence strong Mirror force arises to trap particles in the magnetic mirror. Thus we expect poloidal flows are weak and we show that this is indeed true for ion and impurity flows by using the Moment approach in banana regime. In contrast, it is shown that appreciable amount of flows exist in collisional regime. Collisional impurities in the spherical tokamak edge are used as a prototypical example of such a case. The flow exhibits strong poloidal variation. As a consequence, strong effective parallel flow shear accumulates in the high field side. Implications on controlling fluctuations and meso-scale structures are discussed.
{"title":"Equilibrium Flow Structure with Multiple Ion Species in Magnetically Confined Plasmas of an Arbitrary Aspect Ratio","authors":"Yusuke Kosuga","doi":"10.7566/jpsj.93.064501","DOIUrl":"https://doi.org/10.7566/jpsj.93.064501","url":null,"abstract":"Equilibrium flows of impure plasmas in magnetically confined plasmas of arbitrary aspect ratio are calculated by neoclassical theory. For magnetically confined plasmas with the inverse aspect ratio approaching unity from below, the variation of the magnetic field strength along the field becomes large and as a consequence strong Mirror force arises to trap particles in the magnetic mirror. Thus we expect poloidal flows are weak and we show that this is indeed true for ion and impurity flows by using the Moment approach in banana regime. In contrast, it is shown that appreciable amount of flows exist in collisional regime. Collisional impurities in the spherical tokamak edge are used as a prototypical example of such a case. The flow exhibits strong poloidal variation. As a consequence, strong effective parallel flow shear accumulates in the high field side. Implications on controlling fluctuations and meso-scale structures are discussed.","PeriodicalId":17304,"journal":{"name":"Journal of the Physical Society of Japan","volume":"48 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141146518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This review describes recent significant research developments made on the layered perovskite Sr2RuO4 and discusses current issues from both experimental and theoretical perspectives. Since the discovery of superconductivity in Sr2RuO4 in 1994, studies using high-quality single crystals quickly revealed it to be an archetypal unconventional superconductor among strongly correlated electron systems. In particular, it was thought that the spin-triplet chiral p-wave superconducting state, which breaks time-reversal symmetry, was a prominent possibility. In 2019, however, a new development overturned the past experimental results, and spin-singlet-like behavior became conclusive. Furthermore, innovation in uniaxial strain devices has stimulated researchers to explore changes in the superconducting state by controlling the symmetry and dimensionality of the Fermi surfaces and enhancing the superconducting transition temperature Tc from 1.5 to 3.5 K. A spin-singlet chiral d-wave superconducting state is consistent with most of these recent experimental results. Nevertheless, there are still unnatural aspects that remain to be explained. The focus of this review is on unraveling this mystery. Unlike many other unconventional superconductors, the normal state of Sr2RuO4 exhibits typical Fermi liquid behavior. Nevertheless, to elucidate its superconducting state, it may be essential to go beyond the traditional framework of unconventional superconductivity and recast the theory explicitly considering the multi-orbital aspects of its electronic states. In this review, we describe the frontiers of superconductivity research in Sr2RuO4 and discuss how the remaining issues may be resolved.
这篇综述介绍了最近在层状包晶 Sr2RuO4 方面取得的重大研究进展，并从实验和理论两个角度讨论了当前的问题。自 1994 年在 Sr2RuO4 中发现超导电性以来，利用高质量单晶体进行的研究很快发现它是强相关电子系统中典型的非常规超导体。特别是，人们认为自旋三重手性 p 波超导态打破了时间逆对称性，是一种突出的可能性。然而，2019 年，一项新的进展推翻了过去的实验结果，类自旋单子行为成为定论。此外，单轴应变器件的创新刺激了研究人员探索通过控制费米面的对称性和维度来改变超导态，并将超导转变温度 Tc 从 1.5 K 提高到 3.5 K。自旋小手性 d 波超导态与这些最新实验结果中的大部分相一致。然而，仍有一些不自然的方面有待解释。本综述的重点就是揭开这一谜团。与许多其他非常规超导体不同，Sr2RuO4 的正常态表现出典型的费米液体行为。然而，要阐明它的超导状态，可能必须超越传统的非常规超导框架，明确考虑其电子状态的多轨道方面，重新构建理论。在这篇综述中，我们描述了 Sr2RuO4 超导性研究的前沿，并讨论了如何解决剩余问题。
{"title":"Still Mystery after All These Years —Unconventional Superconductivity of Sr2RuO4—","authors":"Yoshiteru Maeno, Shingo Yonezawa, Aline Ramires","doi":"10.7566/jpsj.93.062001","DOIUrl":"https://doi.org/10.7566/jpsj.93.062001","url":null,"abstract":"This review describes recent significant research developments made on the layered perovskite Sr<sub>2</sub>RuO<sub>4</sub> and discusses current issues from both experimental and theoretical perspectives. Since the discovery of superconductivity in Sr<sub>2</sub>RuO<sub>4</sub> in 1994, studies using high-quality single crystals quickly revealed it to be an archetypal unconventional superconductor among strongly correlated electron systems. In particular, it was thought that the spin-triplet chiral <i>p</i>-wave superconducting state, which breaks time-reversal symmetry, was a prominent possibility. In 2019, however, a new development overturned the past experimental results, and spin-singlet-like behavior became conclusive. Furthermore, innovation in uniaxial strain devices has stimulated researchers to explore changes in the superconducting state by controlling the symmetry and dimensionality of the Fermi surfaces and enhancing the superconducting transition temperature <i>T</i><sub>c</sub> from 1.5 to 3.5 K. A spin-singlet chiral <i>d</i>-wave superconducting state is consistent with most of these recent experimental results. Nevertheless, there are still unnatural aspects that remain to be explained. The focus of this review is on unraveling this mystery. Unlike many other unconventional superconductors, the normal state of Sr<sub>2</sub>RuO<sub>4</sub> exhibits typical Fermi liquid behavior. Nevertheless, to elucidate its superconducting state, it may be essential to go beyond the traditional framework of unconventional superconductivity and recast the theory explicitly considering the multi-orbital aspects of its electronic states. In this review, we describe the frontiers of superconductivity research in Sr<sub>2</sub>RuO<sub>4</sub> and discuss how the remaining issues may be resolved.","PeriodicalId":17304,"journal":{"name":"Journal of the Physical Society of Japan","volume":"47 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141146520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The coexistence of edge states and skin effects provides the topologically protected localized states at the corners of two-dimensional systems. In this paper, we realize such corner states in the two-dimensional Su–Schrieffer–Heeger model with the nonreciprocal hoppings. For the characterization of the real line gap topology, we introduce the (mathbb{Z}_{4}) Berry phase protected by generalized four-fold rotational symmetry. From the physical picture of the adiabatic connection, we find that the value of the (mathbb{Z}_{4}) Berry phase predicts the position of edge states. Additionally, by using the winding number, we characterize the point gap topology of the edge spectra. From the results of these characterizations by the first-order topological invariants, we find that the pair of values of the (mathbb{Z}_{4}) Berry phase and the winding number yields the position of the topologically protected localized states.
{"title":"Hybrid Higher-Order Skin Topological Modes in the Two-Dimensional Su–Schrieffer–Heeger Model with Nonreciprocal Hoppings","authors":"Hiromasa Wakao","doi":"10.7566/jpsj.93.064702","DOIUrl":"https://doi.org/10.7566/jpsj.93.064702","url":null,"abstract":"The coexistence of edge states and skin effects provides the topologically protected localized states at the corners of two-dimensional systems. In this paper, we realize such corner states in the two-dimensional Su–Schrieffer–Heeger model with the nonreciprocal hoppings. For the characterization of the real line gap topology, we introduce the <tex-math space=\"preserve\" version=\"MathJax\">(mathbb{Z}_{4})</tex-math> Berry phase protected by generalized four-fold rotational symmetry. From the physical picture of the adiabatic connection, we find that the value of the <tex-math space=\"preserve\" version=\"MathJax\">(mathbb{Z}_{4})</tex-math> Berry phase predicts the position of edge states. Additionally, by using the winding number, we characterize the point gap topology of the edge spectra. From the results of these characterizations by the first-order topological invariants, we find that the pair of values of the <tex-math space=\"preserve\" version=\"MathJax\">(mathbb{Z}_{4})</tex-math> Berry phase and the winding number yields the position of the topologically protected localized states.","PeriodicalId":17304,"journal":{"name":"Journal of the Physical Society of Japan","volume":"10 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141146521","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The ternary iron antimonide Zr6FeSb2 was synthesized by arc-melting method. The AC susceptibility and electrical resistivity revealed a superconducting transition at 1.3 K, which is between 4.7 and 0.76 K of recently reported ternary iron telluride superconductors Sc6FeTe2 and Zr6FeTe2, respectively.
通过电弧熔融法合成了三元铁锑化物 Zr6FeSb2。交流电感和电阻率显示，在 1.3 K 处出现了超导转变，这与最近报道的三元碲化铁超导体 Sc6FeTe2 和 Zr6FeTe2 的超导转变温度分别介于 4.7 K 和 0.76 K 之间。
{"title":"Superconductivity in Metal-Rich Antimonide Zr6FeSb2","authors":"Ryohei Matsumoto, Ei Murakami, Ryohei Oishi, Sitaram Ramakrishnan, Atsutoshi Ikeda, Shingo Yonezawa, Toshiro Takabatake, Takahiro Onimaru, Minoru Nohara","doi":"10.7566/jpsj.93.065001","DOIUrl":"https://doi.org/10.7566/jpsj.93.065001","url":null,"abstract":"The ternary iron antimonide Zr<sub>6</sub>FeSb<sub>2</sub> was synthesized by arc-melting method. The AC susceptibility and electrical resistivity revealed a superconducting transition at 1.3 K, which is between 4.7 and 0.76 K of recently reported ternary iron telluride superconductors Sc<sub>6</sub>FeTe<sub>2</sub> and Zr<sub>6</sub>FeTe<sub>2</sub>, respectively.","PeriodicalId":17304,"journal":{"name":"Journal of the Physical Society of Japan","volume":"36 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141060695","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Effective utilization of unused heat below 200 °C is a vital issue for a zero-emission society. Here, we propose a two-phase Büttiker–Landauer (BL) ratchet pump using nucleate boiling. Specifically, by fabricating a periodical structure consisting of hot regions (where bubbles and water rise) and cold regions (where water descends diagonally while dissipating heat), we demonstrate that a net flow of ∼13 mm/s can be generated in a nucleate boiling regime (e.g., 115 °C). In addition, we find that a net flow of ∼1 mm/s occurs even in a bubble-free temperature region (e.g., 80 °C), and thus our BL pump works both in temperature regions with and without bubbles seamlessly. Moreover, we explain our experimental results fairly well by proposing a simple model that considers buoyancy force due to the bubbles in a nucleate boiling region. Our findings should contribute to the effective use of energy in the future.
{"title":"Generation of a Net Flow Using a Two-phase Büttiker–Landauer Ratchet Pump in a Nucleate Boiling Region","authors":"Hideyuki Sugioka, Atsushi Miyauchi","doi":"10.7566/jpsj.93.064402","DOIUrl":"https://doi.org/10.7566/jpsj.93.064402","url":null,"abstract":"Effective utilization of unused heat below 200 °C is a vital issue for a zero-emission society. Here, we propose a two-phase Büttiker–Landauer (BL) ratchet pump using nucleate boiling. Specifically, by fabricating a periodical structure consisting of hot regions (where bubbles and water rise) and cold regions (where water descends diagonally while dissipating heat), we demonstrate that a net flow of ∼13 mm/s can be generated in a nucleate boiling regime (e.g., 115 °C). In addition, we find that a net flow of ∼1 mm/s occurs even in a bubble-free temperature region (e.g., 80 °C), and thus our BL pump works both in temperature regions with and without bubbles seamlessly. Moreover, we explain our experimental results fairly well by proposing a simple model that considers buoyancy force due to the bubbles in a nucleate boiling region. Our findings should contribute to the effective use of energy in the future.","PeriodicalId":17304,"journal":{"name":"Journal of the Physical Society of Japan","volume":"35 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140926960","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study proposes a trainable sampling-based solver for combinatorial optimization problems (COPs) using a deep-learning technique called deep unfolding. The proposed solver is based on the Ohzeki method that combines Markov-chain Monte-Carlo (MCMC) and gradient descent, and its step sizes are trained by minimizing a loss function. In the training process, we propose a sampling-based gradient estimation that substitutes auto-differentiation with a variance estimation, thereby circumventing the failure of back propagation due to the non-differentiability of MCMC. The numerical results for a few COPs demonstrated that the proposed solver significantly accelerated the convergence speed compared with the original Ohzeki method.
{"title":"Convergence Acceleration of Markov Chain Monte Carlo-Based Gradient Descent by Deep Unfolding","authors":"Ryo Hagiwara, Satoshi Takabe","doi":"10.7566/jpsj.93.063801","DOIUrl":"https://doi.org/10.7566/jpsj.93.063801","url":null,"abstract":"This study proposes a trainable sampling-based solver for combinatorial optimization problems (COPs) using a deep-learning technique called deep unfolding. The proposed solver is based on the Ohzeki method that combines Markov-chain Monte-Carlo (MCMC) and gradient descent, and its step sizes are trained by minimizing a loss function. In the training process, we propose a sampling-based gradient estimation that substitutes auto-differentiation with a variance estimation, thereby circumventing the failure of back propagation due to the non-differentiability of MCMC. The numerical results for a few COPs demonstrated that the proposed solver significantly accelerated the convergence speed compared with the original Ohzeki method.","PeriodicalId":17304,"journal":{"name":"Journal of the Physical Society of Japan","volume":"161 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140841713","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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