Harnessing non-spatial properties of photons as if they represent an additional independent coordinate underpins the emerging synthetic dimension approach. It enables probing of higher-dimensional physical models within low-dimensional devices, such as on a planar chip where this method is relatively nascent. We demonstrate an integrated thin-film lithium niobate ring resonator that, under dynamic modulation, simulates a tight-binding model with its discrete frequency modes representing lattice sites. Inter-mode coupling, and the simulated lattice geometry, can be reconfigured by controlling the modulating signals. Up to a quasi-3D lattice connectivity with controllable gauge potentials has been achieved by simultaneous synchronized nearest-, second- and third-nearest-neighbor coupling, and verified by acquiring synthetic band structures. Development of synthetic frequency dimension devices in the thin-film lithium niobate photonic integration platform is a key step in increasing the complexity of topological models achievable on a chip, combining efficient electro-optic mode coupling with non-linear effects for long-range mode interactions. Lithium niobate on insulator (LNOI) is emerging as a powerful photonic integration platform for synthetic dimension approaches that enable probing of higher-dimensional physical models within low-dimensional devices. The authors present a LNOI ring device, whose frequency modes represent lattice sites for versatile simulation of tight-binding models with up to three-dimensional connectivity.
{"title":"Reconfigurable synthetic dimension frequency lattices in an integrated lithium niobate ring cavity","authors":"Hiep X. Dinh, Armandas Balčytis, Tomoki Ozawa, Yasutomo Ota, Guanghui Ren, Toshihiko Baba, Satoshi Iwamoto, Arnan Mitchell, Thach G. Nguyen","doi":"10.1038/s42005-024-01676-9","DOIUrl":"10.1038/s42005-024-01676-9","url":null,"abstract":"Harnessing non-spatial properties of photons as if they represent an additional independent coordinate underpins the emerging synthetic dimension approach. It enables probing of higher-dimensional physical models within low-dimensional devices, such as on a planar chip where this method is relatively nascent. We demonstrate an integrated thin-film lithium niobate ring resonator that, under dynamic modulation, simulates a tight-binding model with its discrete frequency modes representing lattice sites. Inter-mode coupling, and the simulated lattice geometry, can be reconfigured by controlling the modulating signals. Up to a quasi-3D lattice connectivity with controllable gauge potentials has been achieved by simultaneous synchronized nearest-, second- and third-nearest-neighbor coupling, and verified by acquiring synthetic band structures. Development of synthetic frequency dimension devices in the thin-film lithium niobate photonic integration platform is a key step in increasing the complexity of topological models achievable on a chip, combining efficient electro-optic mode coupling with non-linear effects for long-range mode interactions. Lithium niobate on insulator (LNOI) is emerging as a powerful photonic integration platform for synthetic dimension approaches that enable probing of higher-dimensional physical models within low-dimensional devices. The authors present a LNOI ring device, whose frequency modes represent lattice sites for versatile simulation of tight-binding models with up to three-dimensional connectivity.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01676-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141315543","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-10DOI: 10.1038/s42005-024-01665-y
Helen S. Ansell, István A. Kovács
Recent cellular-level volumetric brain reconstructions have revealed high levels of anatomic complexity. Determining which structural aspects of the brain to focus on, especially when comparing with computational models and other organisms, remains a major challenge. Here we quantify aspects of this complexity and show evidence that brain anatomy satisfies universal scaling laws, establishing the notion of structural criticality in the cellular structure of the brain. Our framework builds upon understanding of critical systems to provide clear guidance in selecting informative structural properties of cellular brain anatomy. As an illustration, we obtain estimates for critical exponents in the human, mouse and fruit fly brains and show that they are consistent between organisms, to the extent that data limitations allow. Such universal quantities are robust to many of the microscopic details of the cellular structures of individual brains, providing a key step towards generative computational models of the cellular structure of the brain, and also clarifying in which sense one animal may be a suitable anatomic model for another. Cellular-level partial brain reconstructions have revealed the anatomic complexity of the brains of multiple organisms. Here, the authors quantify aspects of this complexity, demonstrating that across organisms the cellular structure of the brain shows universal scaling properties associated with being in the vicinity of criticality.
{"title":"Unveiling universal aspects of the cellular anatomy of the brain","authors":"Helen S. Ansell, István A. Kovács","doi":"10.1038/s42005-024-01665-y","DOIUrl":"10.1038/s42005-024-01665-y","url":null,"abstract":"Recent cellular-level volumetric brain reconstructions have revealed high levels of anatomic complexity. Determining which structural aspects of the brain to focus on, especially when comparing with computational models and other organisms, remains a major challenge. Here we quantify aspects of this complexity and show evidence that brain anatomy satisfies universal scaling laws, establishing the notion of structural criticality in the cellular structure of the brain. Our framework builds upon understanding of critical systems to provide clear guidance in selecting informative structural properties of cellular brain anatomy. As an illustration, we obtain estimates for critical exponents in the human, mouse and fruit fly brains and show that they are consistent between organisms, to the extent that data limitations allow. Such universal quantities are robust to many of the microscopic details of the cellular structures of individual brains, providing a key step towards generative computational models of the cellular structure of the brain, and also clarifying in which sense one animal may be a suitable anatomic model for another. Cellular-level partial brain reconstructions have revealed the anatomic complexity of the brains of multiple organisms. Here, the authors quantify aspects of this complexity, demonstrating that across organisms the cellular structure of the brain shows universal scaling properties associated with being in the vicinity of criticality.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01665-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141315542","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-08DOI: 10.1038/s42005-024-01645-2
Sergei Kozlov, Jérôme Lesueur, Dimitri Roditchev, Cheryl Feuillet-Palma
The electron transport in current-biased superconducting nano-bridges is determined by the motion of the quantum vortex confined in the internal disorder landscape. Here we consider theoretically a simple case of a single or two neighbouring linear defects crossing a nano-bridge. The strong anharmonicity of the vortex motion along the defect leads, upon radio frequency (RF) excitation, to fractional Shapiro steps. In the case of two defects, the vortex motion becomes correlated, characterised by metastable states that can be locked to the RF-drive. The lock-unlock process causes sudden voltage jumps and drops in the voltage-current characteristics that can be observed in experiments. We analyse the parameters that promote these metastable dynamic states and discuss their possible experimental realisations. Vortex motion defines transport properties of type II superconductors. Here, authors study the effect of vortex synchronisation with an external periodic drive, that leads to the effects of integer and fractional Shapiro steps and even creates metastable states.
电流偏压超导纳米桥中的电子传输是由内部无序景观中的量子涡旋运动决定的。在这里，我们从理论上考虑了单个或两个相邻线性缺陷穿过纳米桥的简单情况。在射频（RF）激励下，涡旋沿缺陷运动的强非谐性导致了分数夏皮罗阶跃。在有两个缺陷的情况下，涡旋运动变得相互关联，其特征是可被射频驱动锁定的可变状态。锁定-解锁过程会导致电压-电流特性的突然跳变和下降，这可以在实验中观察到。我们分析了促进这些瞬变动态状态的参数，并讨论了其可能的实验现实。涡旋运动决定了 II 型超导体的传输特性。在此，作者研究了涡旋与外部周期性驱动同步的效应，这种效应会导致整数和分数夏皮罗阶跃效应，甚至产生陨变态。
{"title":"Dynamic metastable vortex states in interacting vortex lines","authors":"Sergei Kozlov, Jérôme Lesueur, Dimitri Roditchev, Cheryl Feuillet-Palma","doi":"10.1038/s42005-024-01645-2","DOIUrl":"10.1038/s42005-024-01645-2","url":null,"abstract":"The electron transport in current-biased superconducting nano-bridges is determined by the motion of the quantum vortex confined in the internal disorder landscape. Here we consider theoretically a simple case of a single or two neighbouring linear defects crossing a nano-bridge. The strong anharmonicity of the vortex motion along the defect leads, upon radio frequency (RF) excitation, to fractional Shapiro steps. In the case of two defects, the vortex motion becomes correlated, characterised by metastable states that can be locked to the RF-drive. The lock-unlock process causes sudden voltage jumps and drops in the voltage-current characteristics that can be observed in experiments. We analyse the parameters that promote these metastable dynamic states and discuss their possible experimental realisations. Vortex motion defines transport properties of type II superconductors. Here, authors study the effect of vortex synchronisation with an external periodic drive, that leads to the effects of integer and fractional Shapiro steps and even creates metastable states.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01645-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141294991","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-08DOI: 10.1038/s42005-024-01673-y
I. Plokhikh, C. Mielke III, H. Nakamura, V. Petricek, Y. Qin, V. Sazgari, J. Küspert, I. Biało, S. Shin, O. Ivashko, J. N. Graham, M. v. Zimmermann, M. Medarde, A. Amato, R. Khasanov, H. Luetkens, M. H. Fischer, M. Z. Hasan, J.-X. Yin, T. Neupert, J. Chang, G. Xu, S. Nakatsuji, E. Pomjakushina, D. J. Gawryluk, Z. Guguchia
The kagome lattice is an intriguing and rich platform for discovering, tuning and understanding the diverse phases of quantum matter, crucial for advancing modern and future electronics. Despite considerable efforts, accessing correlated phases at room temperature has been challenging. Using single-crystal X-ray diffraction, we discovered charge order above room temperature in La(Ru1−xFex)3Si2 (x = 0, 0.01, 0.05), where charge order related to out-of-plane Ru atom displacements appears below TCO,I ≃ 400 K. The secondary charge ordered phase emerges below TCO,II ≃ 80–170 K. Furthermore, first principles calculations reveal both the kagome flat band and the van Hove point near the Fermi energy in LaRu3Si2, driven by Ru-dz2 orbitals. Our results identify LaRu3Si2 as the kagome superconductor with the highest known charge ordering temperature, offering a promising avenue for researching room temperature quantum phases and developing related technologies. The study focuses on the charge order in LaRu3Si2, a material with a kagome lattice structure, discovering a charge-ordered state that persists at or above room temperature. This finding classifies LaRu3Si2 as the kagome superconductor with the highest charge ordering temperature, suggesting potential for applications in devices operating at normal environmental conditions without the need for cooling.
{"title":"Discovery of charge order above room-temperature in the prototypical kagome superconductor La(Ru1−xFex)3Si2","authors":"I. Plokhikh, C. Mielke III, H. Nakamura, V. Petricek, Y. Qin, V. Sazgari, J. Küspert, I. Biało, S. Shin, O. Ivashko, J. N. Graham, M. v. Zimmermann, M. Medarde, A. Amato, R. Khasanov, H. Luetkens, M. H. Fischer, M. Z. Hasan, J.-X. Yin, T. Neupert, J. Chang, G. Xu, S. Nakatsuji, E. Pomjakushina, D. J. Gawryluk, Z. Guguchia","doi":"10.1038/s42005-024-01673-y","DOIUrl":"10.1038/s42005-024-01673-y","url":null,"abstract":"The kagome lattice is an intriguing and rich platform for discovering, tuning and understanding the diverse phases of quantum matter, crucial for advancing modern and future electronics. Despite considerable efforts, accessing correlated phases at room temperature has been challenging. Using single-crystal X-ray diffraction, we discovered charge order above room temperature in La(Ru1−xFex)3Si2 (x = 0, 0.01, 0.05), where charge order related to out-of-plane Ru atom displacements appears below TCO,I ≃ 400 K. The secondary charge ordered phase emerges below TCO,II ≃ 80–170 K. Furthermore, first principles calculations reveal both the kagome flat band and the van Hove point near the Fermi energy in LaRu3Si2, driven by Ru-dz2 orbitals. Our results identify LaRu3Si2 as the kagome superconductor with the highest known charge ordering temperature, offering a promising avenue for researching room temperature quantum phases and developing related technologies. The study focuses on the charge order in LaRu3Si2, a material with a kagome lattice structure, discovering a charge-ordered state that persists at or above room temperature. This finding classifies LaRu3Si2 as the kagome superconductor with the highest charge ordering temperature, suggesting potential for applications in devices operating at normal environmental conditions without the need for cooling.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01673-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141294999","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-07DOI: 10.1038/s42005-024-01683-w
Oleg Kirichek, Christopher R. Lawson, Christy J. Kinane, Andrew J. Caruana, Sean Langridge, Timothy R. Charlton, Peter V. E. McClintock
For decades, superfluid helium has attracted the interest of the scientific community as an extremely pure realisation of a quantum liquid, only accessible at temperatures close to absolute zero. Previously, helium films have only been observed directly using X-rays. However, this method is limited to temperatures above 1 K due to the high levels of energy deposition, and it also suffers from an inability to distinguish between helium isotopes. Here we show that a 3He layer on top of a phase separated mixture film at 170 mK gradually dissolves into the 4He with increasing temperature. We also observe an anomaly in film behaviour near 300 mK and unexpected restoration of the layered structure at 1.5 K which is consistent with a re-entrant phase transition leading to the suppression of superfluidity in the film near 300 mK. Our successful application of neutron scattering to study helium films at ultra-low temperatures opens up new possibilities for future research. Superfluidity, a liquid exhibiting frictionless flow, is so far limited to observations in low-temperature 3He and 4He, where the underlying mechanisms governing the quantum state are complex and different for each isotope, making for a fascinating but challenging phenomenon to study experimentally. The authors use isotope-sensitive neutron reflectometry to investigate mixed 3He/4He superfluid He films on a Si surface, and resolve the structural features and phase transitions that occur with changing temperature.
几十年来，超流体氦一直吸引着科学界的兴趣，因为它是一种纯度极高的量子液体，只有在接近绝对零度的温度下才能获得。以前，人们只能用 X 射线直接观测氦薄膜。然而，由于能量沉积水平较高，这种方法仅限于 1 K 以上的温度，而且无法区分氦的同位素。在这里，我们展示了在 170 mK 温度下，相分离混合物薄膜顶部的 3He 层会随着温度的升高逐渐溶解到 4He 中。我们还在 300 mK 附近观察到了薄膜行为的异常现象，并在 1.5 K 时意外地恢复了层状结构，这与 300 mK 附近导致薄膜超流动性被抑制的重入相变是一致的。我们成功地将中子散射应用于研究超低温下的氦薄膜，为未来的研究开辟了新的可能性。超流态是一种表现出无摩擦流动的液体，迄今为止仅限于在低温3He和4He中观察到，其量子态的基本机制非常复杂，而且每种同位素都不相同，因此实验研究超流态现象非常吸引人，但也极具挑战性。作者利用同位素敏感中子反射仪研究了硅表面上的 3He/4He 混合超流氦薄膜，并解析了随着温度变化而出现的结构特征和相变。
{"title":"Density profile of 3He in a nanoscale 3He-4He superfluid film determined by neutron scattering","authors":"Oleg Kirichek, Christopher R. Lawson, Christy J. Kinane, Andrew J. Caruana, Sean Langridge, Timothy R. Charlton, Peter V. E. McClintock","doi":"10.1038/s42005-024-01683-w","DOIUrl":"10.1038/s42005-024-01683-w","url":null,"abstract":"For decades, superfluid helium has attracted the interest of the scientific community as an extremely pure realisation of a quantum liquid, only accessible at temperatures close to absolute zero. Previously, helium films have only been observed directly using X-rays. However, this method is limited to temperatures above 1 K due to the high levels of energy deposition, and it also suffers from an inability to distinguish between helium isotopes. Here we show that a 3He layer on top of a phase separated mixture film at 170 mK gradually dissolves into the 4He with increasing temperature. We also observe an anomaly in film behaviour near 300 mK and unexpected restoration of the layered structure at 1.5 K which is consistent with a re-entrant phase transition leading to the suppression of superfluidity in the film near 300 mK. Our successful application of neutron scattering to study helium films at ultra-low temperatures opens up new possibilities for future research. Superfluidity, a liquid exhibiting frictionless flow, is so far limited to observations in low-temperature 3He and 4He, where the underlying mechanisms governing the quantum state are complex and different for each isotope, making for a fascinating but challenging phenomenon to study experimentally. The authors use isotope-sensitive neutron reflectometry to investigate mixed 3He/4He superfluid He films on a Si surface, and resolve the structural features and phase transitions that occur with changing temperature.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01683-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141292655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-05DOI: 10.1038/s42005-024-01675-w
Alexander S. Frolov, Dmitry Yu. Usachov, Artem V. Tarasov, Alexander V. Fedorov, Kirill A. Bokai, Ilya Klimovskikh, Vasily S. Stolyarov, Anton I. Sergeev, Alexander N. Lavrov, Vladimir A. Golyashov, Oleg E. Tereshchenko, Giovanni Di Santo, Luca Petacсia, Oliver J. Clark, Jaime Sanchez-Barriga, Lada V. Yashina
The ability to finely tune the properties of magnetic topological insulators (TIs) is crucial for quantum electronics. We studied solid solutions with a general formula GexMn1-xBi2Te4 between two isostructural Z2 TIs, magnetic MnBi2Te4 and nonmagnetic GeBi2Te4 with Z2 invariants of 1;000 and 1;001, respectively. We observed linear x-dependent magnetic properties, composition-independent pairwise exchange interactions, and topological phase transitions (TPTs) between topologically nontrivial phases and the semimetal state. The TPTs are driven purely by the variation of orbital contributions. By tracing the x-dependent Bi 6p contribution to the states near the fundamental gap, the effective spin-orbit coupling variation is extracted. The gapless state observed at x = 0.42 closely resembles a Dirac semimetal above the Néel temperature and shows a magnetic gap below, which is clearly visible in raw photoemission data. The observed behavior demonstrates an ability to precisely control topological and magnetic properties of TIs. Topological insulators with ordered moments of embedded magnetic atoms are viable platforms for quantum electronics, but the practical applications are restricted by the size of their crystals. The authors synthesize a Z2 topological insulator GexMn1-xBi2Te4 in the form of a large crystal with high structural perfection and tunable magnetic and electronic properties.
微调磁性拓扑绝缘体（TI）特性的能力对量子电子学至关重要。我们研究了两种等结构 Z2 TI（磁性 MnBi2Te4 和非磁性 GeBi2Te4）之间通式为 GexMn1-xBi2Te4 的固溶体，它们的 Z2 不变式分别为 1;000 和 1;001。我们观察到了与 x 有关的线性磁性、与组成无关的成对交换相互作用以及拓扑非三维相与半金属态之间的拓扑相变（TPT）。拓扑相变完全是由轨道贡献的变化驱动的。通过追踪基本间隙附近的态随 x 变化的 Bi 6p 贡献，可以提取有效的自旋轨道耦合变化。在 x = 0.42 处观察到的无间隙态非常类似于内耳温度以上的狄拉克半金属，而在内耳温度以下则显示出磁间隙，这在原始光发射数据中清晰可见。观察到的行为表明，我们有能力精确控制拓扑绝缘体的拓扑和磁特性。具有有序嵌入磁性原子矩的拓扑绝缘体是量子电子学的可行平台，但其实际应用受到晶体尺寸的限制。作者合成了一种 Z2 拓扑绝缘体 GexMn1-xBi2Te4，它是一种结构完美、磁性和电子特性可调的大晶体。
{"title":"Magnetic Dirac semimetal state of (Mn,Ge)Bi2Te4","authors":"Alexander S. Frolov, Dmitry Yu. Usachov, Artem V. Tarasov, Alexander V. Fedorov, Kirill A. Bokai, Ilya Klimovskikh, Vasily S. Stolyarov, Anton I. Sergeev, Alexander N. Lavrov, Vladimir A. Golyashov, Oleg E. Tereshchenko, Giovanni Di Santo, Luca Petacсia, Oliver J. Clark, Jaime Sanchez-Barriga, Lada V. Yashina","doi":"10.1038/s42005-024-01675-w","DOIUrl":"10.1038/s42005-024-01675-w","url":null,"abstract":"The ability to finely tune the properties of magnetic topological insulators (TIs) is crucial for quantum electronics. We studied solid solutions with a general formula GexMn1-xBi2Te4 between two isostructural Z2 TIs, magnetic MnBi2Te4 and nonmagnetic GeBi2Te4 with Z2 invariants of 1;000 and 1;001, respectively. We observed linear x-dependent magnetic properties, composition-independent pairwise exchange interactions, and topological phase transitions (TPTs) between topologically nontrivial phases and the semimetal state. The TPTs are driven purely by the variation of orbital contributions. By tracing the x-dependent Bi 6p contribution to the states near the fundamental gap, the effective spin-orbit coupling variation is extracted. The gapless state observed at x = 0.42 closely resembles a Dirac semimetal above the Néel temperature and shows a magnetic gap below, which is clearly visible in raw photoemission data. The observed behavior demonstrates an ability to precisely control topological and magnetic properties of TIs. Topological insulators with ordered moments of embedded magnetic atoms are viable platforms for quantum electronics, but the practical applications are restricted by the size of their crystals. The authors synthesize a Z2 topological insulator GexMn1-xBi2Te4 in the form of a large crystal with high structural perfection and tunable magnetic and electronic properties.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01675-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141264698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-04DOI: 10.1038/s42005-024-01668-9
István Takács, Viktor Ivády
The decoherence of point defect qubits is often governed by the electron spin-nuclear spin hyperfine interaction that can be parameterized by using ab inito calculations in principle. So far most of the theoretical works have focused on the hyperfine interaction of the closest nuclear spins, while the accuracy of the predictions for distinct nuclear spins is barely discussed. Here we demonstrate for the case of the NV center in diamond that the absolute relative error of the computed hyperfine parameters can exceed 100% using an industry standards first-principles code. To overcome this issue, we implement an alternative method and report on significantly improved hyperfine values with $${{{{{{{mathcal{O}}}}}}}}$$ (1%) relative mean error at all distances. The provided accurate hyperfine data for the NV center enables high-precision simulation of NV quantum nodes for quantum information processing and positioning of nuclear spins by comparing experimental and theoretical hyperfine data. Hyperfine interaction is the key term for utilizing individual nuclear spins in solids. This work introduces a method that yields high-accuracy hyperfine values for nuclear spins at arbitrary distances from addressable electron spins, such as the NV center in diamond.
{"title":"Accurate hyperfine tensors for solid state quantum applications: case of the NV center in diamond","authors":"István Takács, Viktor Ivády","doi":"10.1038/s42005-024-01668-9","DOIUrl":"10.1038/s42005-024-01668-9","url":null,"abstract":"The decoherence of point defect qubits is often governed by the electron spin-nuclear spin hyperfine interaction that can be parameterized by using ab inito calculations in principle. So far most of the theoretical works have focused on the hyperfine interaction of the closest nuclear spins, while the accuracy of the predictions for distinct nuclear spins is barely discussed. Here we demonstrate for the case of the NV center in diamond that the absolute relative error of the computed hyperfine parameters can exceed 100% using an industry standards first-principles code. To overcome this issue, we implement an alternative method and report on significantly improved hyperfine values with $${{{{{{{mathcal{O}}}}}}}}$$ (1%) relative mean error at all distances. The provided accurate hyperfine data for the NV center enables high-precision simulation of NV quantum nodes for quantum information processing and positioning of nuclear spins by comparing experimental and theoretical hyperfine data. Hyperfine interaction is the key term for utilizing individual nuclear spins in solids. This work introduces a method that yields high-accuracy hyperfine values for nuclear spins at arbitrary distances from addressable electron spins, such as the NV center in diamond.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01668-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141251535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-04DOI: 10.1038/s42005-024-01679-6
Jin-Hong Park, Jun-Won Rhim
The localized nature of a flat band is understood by the existence of a compact localized eigenstate. However, the localization properties of a partially flat band, ubiquitous in surface modes of topological semimetals, have been unknown. We show that the partially flat band is characterized by a non-normalizable quasi-compact localized state (Q-CLS), which is compactly localized along several directions but extended in at least one direction. The partially flat band develops at momenta where normalizable Bloch wave functions can be obtained from a linear combination of the non-normalizable Q-CLSs. Outside this momentum region, a ghost flat band, unseen from the band structure, is introduced based on a counting argument. Then, we demonstrate that the Wannier function corresponding to the partially flat band exhibits an algebraic decay behavior. Namely, one can have the Wannier obstruction in a band with a vanishing Chern number if it is partially flat. Finally, we develop the construction scheme of a tight-binding model for a topological semimetal by designing a Q-CLS. Compact localized states constitute an auxiliary state representation for a flat-band lattice system with wave functions non-zero only in a finite portion of the lattice. Here, the authors show that in some flat-band systems, these states can be partially “hidden”; surprisingly, these ghost flat bands present an obstruction to be represented as maximally localized Wannier functions.
{"title":"Quasi-localization and Wannier obstruction in partially flat bands","authors":"Jin-Hong Park, Jun-Won Rhim","doi":"10.1038/s42005-024-01679-6","DOIUrl":"10.1038/s42005-024-01679-6","url":null,"abstract":"The localized nature of a flat band is understood by the existence of a compact localized eigenstate. However, the localization properties of a partially flat band, ubiquitous in surface modes of topological semimetals, have been unknown. We show that the partially flat band is characterized by a non-normalizable quasi-compact localized state (Q-CLS), which is compactly localized along several directions but extended in at least one direction. The partially flat band develops at momenta where normalizable Bloch wave functions can be obtained from a linear combination of the non-normalizable Q-CLSs. Outside this momentum region, a ghost flat band, unseen from the band structure, is introduced based on a counting argument. Then, we demonstrate that the Wannier function corresponding to the partially flat band exhibits an algebraic decay behavior. Namely, one can have the Wannier obstruction in a band with a vanishing Chern number if it is partially flat. Finally, we develop the construction scheme of a tight-binding model for a topological semimetal by designing a Q-CLS. Compact localized states constitute an auxiliary state representation for a flat-band lattice system with wave functions non-zero only in a finite portion of the lattice. Here, the authors show that in some flat-band systems, these states can be partially “hidden”; surprisingly, these ghost flat bands present an obstruction to be represented as maximally localized Wannier functions.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01679-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141251539","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-01DOI: 10.1038/s42005-024-01666-x
Zhaohua Lin, Lilei Han, Mi Feng, Ying Liu, Ming Tang
Higher-order structures such as simplicial complexes are ubiquitous in numerous real-world networks. Empirical evidence reveals that interactions among nodes occur not only through edges but also through higher-dimensional simplicial structures such as triangles. Nevertheless, classic models such as the threshold model fail to capture group interactions within these higher-order structures. In this paper, we propose a higher-order non-Markovian social contagion model, considering both higher-order interactions and the non-Markovian characteristics of real-world spreading processes. We develop a mean-field theory to describe its evolutionary dynamics. Simulation results reveal that the theory is capable of predicting the steady state of the model. Our theoretical analyses indicate that there is an equivalence between the higher-order non-Markovian and the higher-order Markovian social contagions. Besides, we find that non-Markovian recovery can boost the system resilience to withstand a large-scale infection or a small-scale infection under different conditions. This work deepens our understanding of the behaviors of higher-order non-Markovian social contagions in the real world. High-order structures are ubiquitous in numerous real-world networks and play a significant role in social contagion phenomena, the authors introduce a novel higher-order non-Markovian social contagion model, addressing limitations of traditional models. Through mean-field theory and simulations, the authors demonstrate that there is an equivalence between the higher-order non-Markovian and the higher-order Markovian social contagions and reveal the resilience enhancement conferred by non-Markovian recovery, shedding light on real-world contagion dynamics.
{"title":"Higher-order non-Markovian social contagions in simplicial complexes","authors":"Zhaohua Lin, Lilei Han, Mi Feng, Ying Liu, Ming Tang","doi":"10.1038/s42005-024-01666-x","DOIUrl":"10.1038/s42005-024-01666-x","url":null,"abstract":"Higher-order structures such as simplicial complexes are ubiquitous in numerous real-world networks. Empirical evidence reveals that interactions among nodes occur not only through edges but also through higher-dimensional simplicial structures such as triangles. Nevertheless, classic models such as the threshold model fail to capture group interactions within these higher-order structures. In this paper, we propose a higher-order non-Markovian social contagion model, considering both higher-order interactions and the non-Markovian characteristics of real-world spreading processes. We develop a mean-field theory to describe its evolutionary dynamics. Simulation results reveal that the theory is capable of predicting the steady state of the model. Our theoretical analyses indicate that there is an equivalence between the higher-order non-Markovian and the higher-order Markovian social contagions. Besides, we find that non-Markovian recovery can boost the system resilience to withstand a large-scale infection or a small-scale infection under different conditions. This work deepens our understanding of the behaviors of higher-order non-Markovian social contagions in the real world. High-order structures are ubiquitous in numerous real-world networks and play a significant role in social contagion phenomena, the authors introduce a novel higher-order non-Markovian social contagion model, addressing limitations of traditional models. Through mean-field theory and simulations, the authors demonstrate that there is an equivalence between the higher-order non-Markovian and the higher-order Markovian social contagions and reveal the resilience enhancement conferred by non-Markovian recovery, shedding light on real-world contagion dynamics.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01666-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141187643","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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