Pub Date : 2025-11-26DOI: 10.1038/s41567-025-03086-2
Francesco A. Mele, Antonio A. Mele, Lennart Bittel, Jens Eisert, Vittorio Giovannetti, Ludovico Lami, Lorenzo Leone, Salvatore F. E. Oliviero
Quantum measurements are probabilistic and, in general, provide only partial information about the underlying quantum state. Obtaining a full classical description of an unknown quantum state requires the analysis of several different measurements, a task known as quantum-state tomography. Here we analyse the ultimate achievable performance in the tomography of continuous-variable systems, such as bosonic and quantum optical systems. We prove that tomography of these systems is extremely inefficient in terms of time resources, much more so than tomography of finite-dimensional systems such as qubits. Not only does the minimum number of state copies needed for tomography scale exponentially with the number of modes, but, even for low-energy states, it also scales unfavourably with the trace-distance error between the original state and its estimated classical description. On a more positive note, we prove that the tomography of Gaussian states is efficient by establishing a bound on the trace-distance error made when approximating a Gaussian state from knowledge of the first and second moments within a specified error bound. Last, we demonstrate that the tomography of non-Gaussian states prepared through Gaussian unitaries and a few local non-Gaussian evolutions is efficient and experimentally feasible. Finding a classical description of a quantum state can require resource-intensive tomography protocols. It has now been shown that, for bosonic systems, tomography is extremely inefficient in general, but can be done efficiently for some useful states.
{"title":"Learning quantum states of continuous-variable systems","authors":"Francesco A. Mele, Antonio A. Mele, Lennart Bittel, Jens Eisert, Vittorio Giovannetti, Ludovico Lami, Lorenzo Leone, Salvatore F. E. Oliviero","doi":"10.1038/s41567-025-03086-2","DOIUrl":"10.1038/s41567-025-03086-2","url":null,"abstract":"Quantum measurements are probabilistic and, in general, provide only partial information about the underlying quantum state. Obtaining a full classical description of an unknown quantum state requires the analysis of several different measurements, a task known as quantum-state tomography. Here we analyse the ultimate achievable performance in the tomography of continuous-variable systems, such as bosonic and quantum optical systems. We prove that tomography of these systems is extremely inefficient in terms of time resources, much more so than tomography of finite-dimensional systems such as qubits. Not only does the minimum number of state copies needed for tomography scale exponentially with the number of modes, but, even for low-energy states, it also scales unfavourably with the trace-distance error between the original state and its estimated classical description. On a more positive note, we prove that the tomography of Gaussian states is efficient by establishing a bound on the trace-distance error made when approximating a Gaussian state from knowledge of the first and second moments within a specified error bound. Last, we demonstrate that the tomography of non-Gaussian states prepared through Gaussian unitaries and a few local non-Gaussian evolutions is efficient and experimentally feasible. Finding a classical description of a quantum state can require resource-intensive tomography protocols. It has now been shown that, for bosonic systems, tomography is extremely inefficient in general, but can be done efficiently for some useful states.","PeriodicalId":19100,"journal":{"name":"Nature Physics","volume":"21 12","pages":"2002-2008"},"PeriodicalIF":18.4,"publicationDate":"2025-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.comhttps://www.nature.com/articles/s41567-025-03086-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145599383","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 : 2025-11-26DOI: 10.1038/s41567-025-03109-y
Khai That Ton, Chang Xu, Ioannis Ioannidis, Lucas Schneider, Thore Posske, Roland Wiesendanger, Dirk K. Morr, Jens Wiebe
Probing spatially confined quantum states from afar—a long-sought goal to minimize external interference—has been proposed to be feasible in condensed-matter systems through the coherent projection of the state. This can be achieved by engineering the eigenstates of the electron sea that surrounds the quantum state using cages built atom by atom, the so-called quantum corrals. However, the demonstration of the coherent nature of the projection and manipulation of its quantum composition are still important goals. Here we show this for the coherent projection of a Yu–Shiba–Rusinov quantum state that is induced by a magnetic impurity, using the eigenmodes of corrals on the surface of a superconductor. This enables us to manipulate the particle–hole composition of the projected state by tuning the corral eigenmodes through the Fermi energy. Our results demonstrate a controlled non-local method for the detection of magnet–superconductor hybrid quantum states. Coherently projecting a quantum state may allow it to be probed from a distance. This is now demonstrated for a Yu–Shiba–Rusinov state using a quantum corral.
{"title":"Non-local detection of coherent Yu–Shiba–Rusinov quantum projections","authors":"Khai That Ton, Chang Xu, Ioannis Ioannidis, Lucas Schneider, Thore Posske, Roland Wiesendanger, Dirk K. Morr, Jens Wiebe","doi":"10.1038/s41567-025-03109-y","DOIUrl":"10.1038/s41567-025-03109-y","url":null,"abstract":"Probing spatially confined quantum states from afar—a long-sought goal to minimize external interference—has been proposed to be feasible in condensed-matter systems through the coherent projection of the state. This can be achieved by engineering the eigenstates of the electron sea that surrounds the quantum state using cages built atom by atom, the so-called quantum corrals. However, the demonstration of the coherent nature of the projection and manipulation of its quantum composition are still important goals. Here we show this for the coherent projection of a Yu–Shiba–Rusinov quantum state that is induced by a magnetic impurity, using the eigenmodes of corrals on the surface of a superconductor. This enables us to manipulate the particle–hole composition of the projected state by tuning the corral eigenmodes through the Fermi energy. Our results demonstrate a controlled non-local method for the detection of magnet–superconductor hybrid quantum states. Coherently projecting a quantum state may allow it to be probed from a distance. This is now demonstrated for a Yu–Shiba–Rusinov state using a quantum corral.","PeriodicalId":19100,"journal":{"name":"Nature Physics","volume":"22 1","pages":"54-60"},"PeriodicalIF":18.4,"publicationDate":"2025-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.comhttps://www.nature.com/articles/s41567-025-03109-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145599905","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 : 2025-11-24DOI: 10.1038/s41567-025-03096-0
Leon Lettermann, Mirko Singer, Smilla Steinbrück, Falko Ziebert, Sachie Kanatani, Photini Sinnis, Friedrich Frischknecht, Ulrich S. Schwarz
Malaria parasites are injected by female mosquitoes into the skin of the vertebrate host and start to quickly move on helical trajectories, making them a medically highly relevant model system of active chiral particles. Here we find that these parasites always move on right-handed helices by analysing their three-dimensional motion in synthetic hydrogels. Furthermore, they transition to clockwise circular motion when they reach a two-dimensional substrate, which is the opposite direction to when circling on a two-dimensional substrate in a medium. This suggests that malaria parasites have evolved chirality as a means to control their transitions between three-dimensional and two-dimensional environments. Using a sandwich assay, we show that chirality also determines their transition from two-dimensional to three-dimensional motion. Combining a theory for gliding motility with two-sided traction force and super-resolution microscopies, we find that the most probable basis for the observed macroscopic chirality in both two and three dimensions is the asymmetric release of adhesion molecules at the apical polar ring. Our results suggest that the slender forms of the malaria parasites that start an infection have evolved very strong chirality because they have to switch between different physical environments. Malaria parasites move on helical trajectories when infecting their hosts. Now it is shown that they use right-handed chirality to control their motion patterns, and that this chirality is linked to the way they release adhesion molecules.
{"title":"Chirality of malaria parasites determines their motion patterns","authors":"Leon Lettermann, Mirko Singer, Smilla Steinbrück, Falko Ziebert, Sachie Kanatani, Photini Sinnis, Friedrich Frischknecht, Ulrich S. Schwarz","doi":"10.1038/s41567-025-03096-0","DOIUrl":"10.1038/s41567-025-03096-0","url":null,"abstract":"Malaria parasites are injected by female mosquitoes into the skin of the vertebrate host and start to quickly move on helical trajectories, making them a medically highly relevant model system of active chiral particles. Here we find that these parasites always move on right-handed helices by analysing their three-dimensional motion in synthetic hydrogels. Furthermore, they transition to clockwise circular motion when they reach a two-dimensional substrate, which is the opposite direction to when circling on a two-dimensional substrate in a medium. This suggests that malaria parasites have evolved chirality as a means to control their transitions between three-dimensional and two-dimensional environments. Using a sandwich assay, we show that chirality also determines their transition from two-dimensional to three-dimensional motion. Combining a theory for gliding motility with two-sided traction force and super-resolution microscopies, we find that the most probable basis for the observed macroscopic chirality in both two and three dimensions is the asymmetric release of adhesion molecules at the apical polar ring. Our results suggest that the slender forms of the malaria parasites that start an infection have evolved very strong chirality because they have to switch between different physical environments. Malaria parasites move on helical trajectories when infecting their hosts. Now it is shown that they use right-handed chirality to control their motion patterns, and that this chirality is linked to the way they release adhesion molecules.","PeriodicalId":19100,"journal":{"name":"Nature Physics","volume":"22 1","pages":"112-122"},"PeriodicalIF":18.4,"publicationDate":"2025-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145582889","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Pub Date : 2025-11-24DOI: 10.1038/s41567-025-03100-7
Kai Du, Daegeun Jo, Xianghan Xu, Fei-Ting Huang, Ming-Hao Lee, Ming-Wen Chu, Kefeng Wang, Xiaoyu Guo, Liuyan Zhao, David Vanderbilt, Hyun-Woo Lee, Sang-Wook Cheong
Breaking spatial-inversion or time-reversal symmetry in solids leads to transverse electromagnetic effects such as the anomalous Hall effect, Faraday rotation, non-reciprocal directional dichroism and off-diagonal linear magnetoelectricity. These are all tied to the framework of magnetic toroidal invariance. Here we introduce a distinct class of transverse electromagnetic responses that arise from electric toroidal invariance in ferro-rotational systems that preserve both inversion and time-reversal symmetries. It is different from that governed by magnetic toroidal invariance. We demonstrate a high-order off-diagonal magnetic susceptibility of ferro-rotational domains and a reduced linear diagonal magnetic susceptibility at these domain walls in doped ilmenite FeTiO3. Our results reveal the presence of anomalous transverse susceptibilities in ferro-rotational materials with spontaneous electric toroidal moments. Therefore, our findings illustrate emergent functionalities of ferro-rotational materials. Magnetic toroidal invariance generates transverse electromagnetic effects in materials with broken symmetries. Now a distinct magnetic response is shown to emerge in ferro-rotational systems in which both inversion and time-reversal symmetries are preserved.
{"title":"Electric toroidal invariance generates distinct transverse electromagnetic responses","authors":"Kai Du, Daegeun Jo, Xianghan Xu, Fei-Ting Huang, Ming-Hao Lee, Ming-Wen Chu, Kefeng Wang, Xiaoyu Guo, Liuyan Zhao, David Vanderbilt, Hyun-Woo Lee, Sang-Wook Cheong","doi":"10.1038/s41567-025-03100-7","DOIUrl":"10.1038/s41567-025-03100-7","url":null,"abstract":"Breaking spatial-inversion or time-reversal symmetry in solids leads to transverse electromagnetic effects such as the anomalous Hall effect, Faraday rotation, non-reciprocal directional dichroism and off-diagonal linear magnetoelectricity. These are all tied to the framework of magnetic toroidal invariance. Here we introduce a distinct class of transverse electromagnetic responses that arise from electric toroidal invariance in ferro-rotational systems that preserve both inversion and time-reversal symmetries. It is different from that governed by magnetic toroidal invariance. We demonstrate a high-order off-diagonal magnetic susceptibility of ferro-rotational domains and a reduced linear diagonal magnetic susceptibility at these domain walls in doped ilmenite FeTiO3. Our results reveal the presence of anomalous transverse susceptibilities in ferro-rotational materials with spontaneous electric toroidal moments. Therefore, our findings illustrate emergent functionalities of ferro-rotational materials. Magnetic toroidal invariance generates transverse electromagnetic effects in materials with broken symmetries. Now a distinct magnetic response is shown to emerge in ferro-rotational systems in which both inversion and time-reversal symmetries are preserved.","PeriodicalId":19100,"journal":{"name":"Nature Physics","volume":"22 1","pages":"61-67"},"PeriodicalIF":18.4,"publicationDate":"2025-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145582890","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Pub Date : 2025-11-21DOI: 10.1038/s41567-025-03097-z
Sarah A. Burke
Excitons are bound electron–hole pairs that are usually either tightly bound or spread across a material. Signatures of hybrid excitons that mix both characters have now been observed at organic–semiconductor interfaces.
{"title":"Hybrid excitons span two worlds","authors":"Sarah A. Burke","doi":"10.1038/s41567-025-03097-z","DOIUrl":"10.1038/s41567-025-03097-z","url":null,"abstract":"Excitons are bound electron–hole pairs that are usually either tightly bound or spread across a material. Signatures of hybrid excitons that mix both characters have now been observed at organic–semiconductor interfaces.","PeriodicalId":19100,"journal":{"name":"Nature Physics","volume":"21 12","pages":"1879-1880"},"PeriodicalIF":18.4,"publicationDate":"2025-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145559859","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Pub Date : 2025-11-20DOI: 10.1038/s41567-025-03071-9
Sergi Batlle Porro, Dumitru Călugăru, Haoyu Hu, Roshan Krishna Kumar, Niels C. H. Hesp, Kenji Watanabe, Takashi Taniguchi, B. Andrei Bernevig, Petr Stepanov, Frank H. L. Koppens
A full microscopic description of the correlated insulators and superconductivity that occur in the flat bands of magic angle twisted bilayer graphene has not yet been found. Electronic transport and scanning tunnelling microscopy experiments have suggested a dichotomy between local and extended electronic orbitals, but definitive evidence for the coexistence of these two carrier types is still sought after. Here we report local photothermoelectric measurements in the flat electronic bands of symmetrically twisted trilayer graphene. We observe oscillations of the Seebeck coefficient around integer fillings of the flat band, signalling the presence of electron correlations, coupled with a breakdown of the predictions of the Mott formula. Our measurements reveal an overall negative offset of the Seebeck coefficient and peaks of the local photovoltage values at all positive integer fillings of the moiré superlattice. This further indicates a deviation from the classical two-band semiconductor Seebeck response. Our findings may be interpreted using the heavy-fermion model in the topological flat bands of moiré graphene and highlight an avenue to apply local thermoelectric measurements to other strongly correlated materials. A proposed theoretical explanation for the electronic behaviour of moiré graphene is the coexistence of light and heavy electrons. Now local thermoelectric measurements hint that this model could be accurate.
{"title":"Photovoltage microscopy of symmetrically twisted trilayer graphene","authors":"Sergi Batlle Porro, Dumitru Călugăru, Haoyu Hu, Roshan Krishna Kumar, Niels C. H. Hesp, Kenji Watanabe, Takashi Taniguchi, B. Andrei Bernevig, Petr Stepanov, Frank H. L. Koppens","doi":"10.1038/s41567-025-03071-9","DOIUrl":"10.1038/s41567-025-03071-9","url":null,"abstract":"A full microscopic description of the correlated insulators and superconductivity that occur in the flat bands of magic angle twisted bilayer graphene has not yet been found. Electronic transport and scanning tunnelling microscopy experiments have suggested a dichotomy between local and extended electronic orbitals, but definitive evidence for the coexistence of these two carrier types is still sought after. Here we report local photothermoelectric measurements in the flat electronic bands of symmetrically twisted trilayer graphene. We observe oscillations of the Seebeck coefficient around integer fillings of the flat band, signalling the presence of electron correlations, coupled with a breakdown of the predictions of the Mott formula. Our measurements reveal an overall negative offset of the Seebeck coefficient and peaks of the local photovoltage values at all positive integer fillings of the moiré superlattice. This further indicates a deviation from the classical two-band semiconductor Seebeck response. Our findings may be interpreted using the heavy-fermion model in the topological flat bands of moiré graphene and highlight an avenue to apply local thermoelectric measurements to other strongly correlated materials. A proposed theoretical explanation for the electronic behaviour of moiré graphene is the coexistence of light and heavy electrons. Now local thermoelectric measurements hint that this model could be accurate.","PeriodicalId":19100,"journal":{"name":"Nature Physics","volume":"21 12","pages":"1934-1941"},"PeriodicalIF":18.4,"publicationDate":"2025-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145554234","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Pub Date : 2025-11-19DOI: 10.1038/s41567-025-03091-5
Islay O. Robertson, Benjamin Whitefield, Sam C. Scholten, Priya Singh, Alexander J. Healey, Philipp Reineck, Mehran Kianinia, Gergely Barcza, Viktor Ivády, David A. Broadway, Igor Aharonovich, Jean-Philippe Tetienne
Bright point-defect emitters in hexagonal boron nitride have potential applications in quantum sensing and other technologies. However, it can be difficult to correctly identify the microscopic nature of observed defects, creating challenges for further development. A class of bright emitters exhibiting optically detected magnetic resonance with no resolvable zero-field splitting has been observed in hexagonal boron nitride across a broad range of wavelengths. However, the microscopic structure of the defects and the physical origin of their optically detected magnetic resonance signal have still not been identified. Here we describe a model that accounts for and provides a physical explanation for all key experimental features of the spin-resolved photodynamics of ensembles and single emitters. The model, inspired by the radical-pair mechanism from spin chemistry, assumes a pair of nearby point defects, one of which is optically active. Using first-principles calculations, we show that simple defect pairs made of common carbon defects provide a plausible realization of our model. As well as addressing open questions about defects in hexagonal boron nitride, our model may also explain similar phenomena observed in other wide-bandgap semiconductors. Optical spin defects in semiconductors are crucial for applications, but it is often difficult to establish their microscopic origin. A mechanism for the spin behaviour of a family of bright emitters in hexagonal boron nitride has now been identified.
{"title":"A charge transfer mechanism for optically addressable solid-state spin pairs","authors":"Islay O. Robertson, Benjamin Whitefield, Sam C. Scholten, Priya Singh, Alexander J. Healey, Philipp Reineck, Mehran Kianinia, Gergely Barcza, Viktor Ivády, David A. Broadway, Igor Aharonovich, Jean-Philippe Tetienne","doi":"10.1038/s41567-025-03091-5","DOIUrl":"10.1038/s41567-025-03091-5","url":null,"abstract":"Bright point-defect emitters in hexagonal boron nitride have potential applications in quantum sensing and other technologies. However, it can be difficult to correctly identify the microscopic nature of observed defects, creating challenges for further development. A class of bright emitters exhibiting optically detected magnetic resonance with no resolvable zero-field splitting has been observed in hexagonal boron nitride across a broad range of wavelengths. However, the microscopic structure of the defects and the physical origin of their optically detected magnetic resonance signal have still not been identified. Here we describe a model that accounts for and provides a physical explanation for all key experimental features of the spin-resolved photodynamics of ensembles and single emitters. The model, inspired by the radical-pair mechanism from spin chemistry, assumes a pair of nearby point defects, one of which is optically active. Using first-principles calculations, we show that simple defect pairs made of common carbon defects provide a plausible realization of our model. As well as addressing open questions about defects in hexagonal boron nitride, our model may also explain similar phenomena observed in other wide-bandgap semiconductors. Optical spin defects in semiconductors are crucial for applications, but it is often difficult to establish their microscopic origin. A mechanism for the spin behaviour of a family of bright emitters in hexagonal boron nitride has now been identified.","PeriodicalId":19100,"journal":{"name":"Nature Physics","volume":"21 12","pages":"1981-1987"},"PeriodicalIF":18.4,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145545451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Pub Date : 2025-11-19DOI: 10.1038/s41567-025-03112-3
R. Tyburski, M. Shin, S. You, K. Nam, M. Soldemo, A. Girelli, M. Bin, S. Lee, I. Andronis, Y. Han, S. Jeong, R. A. Oggenfuss, R. Mankowsky, D. Babich, X. Liu, S. Zerdane, T. Katayama, H. Lemke, F. Perakis, A. Nilsson, K. H. Kim
The fragile-to-strong transition in supercooled water, where the relaxation dynamics shift from non-Arrhenius to Arrhenius behaviour, has been hypothesized to explain its anomalous dynamic properties. However, this transition remains unresolved, as previous ultrafast experimental studies of bulk water dynamics were limited to temperatures far from the proposed transition due to rapid crystallization. Here we use an infrared laser pump and an ultrashort X-ray probe to measure the structural relaxation in micrometre-sized water droplets, evaporatively cooled at timescales ranging from femtoseconds to nanoseconds. Our experimental data show a dynamic crossover at around 233 K. Below this temperature, the relaxation dynamics deviate from simple power-law fits and follow a shallower temperature dependence. Molecular dynamics simulations successfully reproduce our findings. Water has remarkable dynamic properties; a transition from a fragile to a strong liquid has been proposed to explain how they change on cooling. Experiments now show evidence for such a transition in bulk supercooled water at around 233 K.
{"title":"Observation of a dynamic transition in bulk supercooled water","authors":"R. Tyburski, M. Shin, S. You, K. Nam, M. Soldemo, A. Girelli, M. Bin, S. Lee, I. Andronis, Y. Han, S. Jeong, R. A. Oggenfuss, R. Mankowsky, D. Babich, X. Liu, S. Zerdane, T. Katayama, H. Lemke, F. Perakis, A. Nilsson, K. H. Kim","doi":"10.1038/s41567-025-03112-3","DOIUrl":"10.1038/s41567-025-03112-3","url":null,"abstract":"The fragile-to-strong transition in supercooled water, where the relaxation dynamics shift from non-Arrhenius to Arrhenius behaviour, has been hypothesized to explain its anomalous dynamic properties. However, this transition remains unresolved, as previous ultrafast experimental studies of bulk water dynamics were limited to temperatures far from the proposed transition due to rapid crystallization. Here we use an infrared laser pump and an ultrashort X-ray probe to measure the structural relaxation in micrometre-sized water droplets, evaporatively cooled at timescales ranging from femtoseconds to nanoseconds. Our experimental data show a dynamic crossover at around 233 K. Below this temperature, the relaxation dynamics deviate from simple power-law fits and follow a shallower temperature dependence. Molecular dynamics simulations successfully reproduce our findings. Water has remarkable dynamic properties; a transition from a fragile to a strong liquid has been proposed to explain how they change on cooling. Experiments now show evidence for such a transition in bulk supercooled water at around 233 K.","PeriodicalId":19100,"journal":{"name":"Nature Physics","volume":"22 1","pages":"21-26"},"PeriodicalIF":18.4,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145545452","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Pub Date : 2025-11-18DOI: 10.1038/s41567-025-03084-4
Matthias Christandl
The second law of thermodynamics says that entropy may only ever increase during the conversion of one physical state into another. Finding an analogous quantity to characterize the conversion of entangled quantum states has been a rollercoaster ride.
{"title":"A cornerstone of entanglement theory restored","authors":"Matthias Christandl","doi":"10.1038/s41567-025-03084-4","DOIUrl":"10.1038/s41567-025-03084-4","url":null,"abstract":"The second law of thermodynamics says that entropy may only ever increase during the conversion of one physical state into another. Finding an analogous quantity to characterize the conversion of entangled quantum states has been a rollercoaster ride.","PeriodicalId":19100,"journal":{"name":"Nature Physics","volume":"21 12","pages":"1881-1882"},"PeriodicalIF":18.4,"publicationDate":"2025-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145536043","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Pub Date : 2025-11-17DOI: 10.1038/s41567-025-03099-x
Matthew Jankousky, Dimitar Pashov, João H. Mazo, Ross E. Larsen, Vladimir Dobrosavljević, Mark van Schilfgaarde, Vladan Stevanović
The localization of electrons caused by atomic disorder is a well-known phenomenon. However, under which circumstances electrons remain delocalized and retain band-like characteristics even when the crystal structure is completely absent, as found in certain amorphous solids, is less well understood. Here, to probe this phenomenon, we develop a fully first-principles description of the electronic structure and charge transport in amorphous materials, which combines a representation of the amorphous state as a composite (ensemble) of local environments and the state-of-the-art many-body electronic structure methods. Using amorphous In2O3 as an example, we demonstrate the accuracy of our approach in reproducing the band-like nature of the conduction electrons as well as their disorder-limited mobility. Our approach reveals the physical origins responsible for the electron delocalization and survival of the band dispersions despite the absence of long-range order. The standard band structure picture cannot be applied to amorphous materials as they lack crystal symmetry. Now a first-principles approach that captures the possibility of band-like electron transport in amorphous solids is presented, with In2O3 as an example.
{"title":"Effective bands and band-like electron transport in amorphous solids","authors":"Matthew Jankousky, Dimitar Pashov, João H. Mazo, Ross E. Larsen, Vladimir Dobrosavljević, Mark van Schilfgaarde, Vladan Stevanović","doi":"10.1038/s41567-025-03099-x","DOIUrl":"10.1038/s41567-025-03099-x","url":null,"abstract":"The localization of electrons caused by atomic disorder is a well-known phenomenon. However, under which circumstances electrons remain delocalized and retain band-like characteristics even when the crystal structure is completely absent, as found in certain amorphous solids, is less well understood. Here, to probe this phenomenon, we develop a fully first-principles description of the electronic structure and charge transport in amorphous materials, which combines a representation of the amorphous state as a composite (ensemble) of local environments and the state-of-the-art many-body electronic structure methods. Using amorphous In2O3 as an example, we demonstrate the accuracy of our approach in reproducing the band-like nature of the conduction electrons as well as their disorder-limited mobility. Our approach reveals the physical origins responsible for the electron delocalization and survival of the band dispersions despite the absence of long-range order. The standard band structure picture cannot be applied to amorphous materials as they lack crystal symmetry. Now a first-principles approach that captures the possibility of band-like electron transport in amorphous solids is presented, with In2O3 as an example.","PeriodicalId":19100,"journal":{"name":"Nature Physics","volume":"22 1","pages":"88-93"},"PeriodicalIF":18.4,"publicationDate":"2025-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145531881","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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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