Nature, 2022 1 20th, No.601,No.7893.

Nature, 65438+20221October 20th, No.601Vol.7893.

Astronomy astronomy

Star formation near the sun is driven by local bubble expansion.

The expansion of local bubbles promotes the formation of stars near the sun.

Authors: Catherine Zucker, Arisha A. Goodman, Joe? O Alves, Shmuel Bialy, Michael Foley, Joshua S. Spiegel, et al.

Link:

/articles/s 4 1586-02 1-04286-5

abstract

For decades, we have known that the sun is located in a local bubble, that is, a cavity composed of low-density high-temperature plasma, surrounded by a layer of cold neutral gas and dust. However, due to the low-resolution model of local interstellar medium, the exact shape and scope of this shell, the dynamics and time scale of its formation and its relationship with the formation of nearby stars are still uncertain.

Using new spatial and dynamic constraints, the research team analyzed the three-dimensional position, shape and motion of dense gas and young stars within 200 pc of the sun. They found that almost all star-forming complexes near the sun are located on the surface of local bubbles, and their young stars mainly expand outward perpendicular to the surface of bubbles.

Tracking the trajectories of these young stars supports the statement that local bubbles originated from the birth and death (supernova) explosion of stars near the bubble center about 654.38+400 million years ago. The expansion of local bubbles generated by supernovae has rolled up the surrounding interstellar medium and formed an expanded shell, which has now broken and collapsed into the most obvious molecular cloud nearby, thus providing strong observation support for the theory of supernova-driven star formation.

abstract

For decades, we have known that the sun is located in a local bubble, which is a cavity composed of low density and high temperature plasma, surrounded by cold neutral gas and dust. However, the exact shape and scope of this shell, the dynamics and time scale of its formation, and its relationship with the formation of nearby stars are still uncertain, mainly due to the low-resolution model of the local interstellar medium. Here, we report the analysis of the three-dimensional position, shape and motion of dense gas and young stars in 200 years? Use new spatial and dynamic constraints. We find that almost all star-forming complexes near the sun are located on the surface of local bubbles, and their young stars mainly expand outward perpendicular to the surface of bubbles. Tracing back to the movement of these young stars supports the picture that the origin of local bubbles is the explosion of star birth and death (supernova) near the center of bubbles from about 14. Myra: Before. The expansion of local bubbles produced by supernovae swept the surrounding interstellar medium into an extended shell, which has now broken and collapsed into the most prominent molecular cloud nearby, which in turn provided strong observation support for the supernova-driven star formation theory.

Star formation triggered by black holes in dwarf galaxy Henize 2- 10

Black holes trigger the formation of stars in the dwarf galaxy Henize 2- 10.

Author: Zachary Shute &; Amy lane

Link:

/articles/s 4 1586-02 1-042 15-6

abstract

In some dwarf galaxies with active galactic nuclei, people have observed outflow driven by black holes, which may play a role in heating and ejecting gas (thus inhibiting star formation), just like in larger galaxies. At present, it is not clear to what extent the outflow of black holes can trigger the formation of stars in dwarf galaxies, because the work in this field has been mainly concentrated on massive galaxies before, and there is almost no observational evidence.

Henize 2- 10 is a dwarf burst galaxy. It is reported that there is a massive black hole in its center, but this explanation has been controversial because some observational evidence is consistent with supernova debris. At a distance of about 9 Mpc, there is an opportunity to understand the central region and determine whether there is evidence that the outflow of black holes affects the formation of stars.

The research team reported the optical observation results of Henize 2- 10, and its linear resolution was several parsec. They found an ionized filament about 150 pc long, connecting the black hole region with the latest star formation region. Spectroscopy reveals a position-velocity structure similar to a sine wave, which is described by a simple precession bipolar outflow. The research team concluded that the outflow of black holes triggered the formation of stars.

abstract

Black hole-driven outflows have been observed in some dwarf galaxies with active galactic nuclei, and may have played a role in heating and expelling gas (thus inhibiting star formation), just like in larger galaxies. It is unclear to what extent the outflow of black holes can trigger the formation of stars in dwarf galaxies, because the work in this field has been focused on massive galaxies before, and there is little observation evidence. Henize 2- 10 is a dwarf exploding galaxy. It has been reported that there is a massive black hole in its center, although this explanation has been controversial, because some aspects of observation evidence are also consistent with supernova remnants. The distance is about 9? Mpc, which provides an opportunity to distinguish the central region and determine whether there is evidence that black hole outflow affects star formation. We report the optical observation of Henize 2- 10, and its linear resolution is several parsec. We found that an offline line about 150 PC long connects the black hole region with the location where the nearest star formed. Spectroscopy reveals a sinusoidal position-velocity structure, which can be well described by a simple precession bipolar outflow. We concluded that this outflow of black holes triggered the formation of stars.

Physics physics

Topological three-phase transformation in non-Hermite Floquet quasicrystals

Topological three-phase transformation of non-Hermite-floquet quasicrystals

Authors: Sebastian Weidemann, Mark Kramer, Stefano Longji &; Alexander Samet

Link:

/articles/s 4 1586-02 1-04253-0

abstract

Phase transition connects different states of matter, usually accompanied by spontaneous destruction of symmetry. An important type of phase transition is mobility phase transition, in which the famous Anderson localization increases randomness and leads to metal-insulator phase transition. The introduction of topology in condensed matter physics leads to topological phase transition and the discovery of topological insulator materials.

The phase transition of non-Hermite system symmetry describes the transition to average conservation energy and new topological phase. Volume conductivity, topology and non-Hermite symmetry breaking seem to originate from different physics, so they may appear as independent phenomena. However, in non-Hermite quasicrystals, this transformation can be related by forming three-phase transformation.

The research group reported an experimental observation of triple phase transition, in which changing a single parameter will cause localized (metal-insulator), topological and even-odd time symmetry breaking (energy) phase transition. Physics is a time-driven dissipative quasicrystal.

The research group realized their idea by coupling photon quantum walking in the optical fiber loop, and emphasized the correlation of topology, symmetry breaking and mobility phase transition in non-Hermite quasicrystal synthetic materials. The research results are expected to be applied to phase change devices, in which body-side transport and energy or particle exchange with the environment can be predicted and controlled.

abstract

Phase transition connects different states of matter, usually accompanied by spontaneous symmetry breaking. An important category of phase transition is mobility transition, which includes the well-known Anderson localization. Increasing randomness will lead to metal-insulator transition. The introduction of topology in condensed matter physics leads to topological phase transition and the discovery of materials as topological insulators. The phase transition in the symmetry of non-Hermite system describes the transition to average conservation energy and new topological phase. Bulk conductivity, topology and non-Hermite symmetry breaking seem to come from different physics, so they may appear as separable phenomena. However, in non-Hermite quasicrystals, this transformation can be related by forming three-phase transformation. Here, we report an experimental observation of three-phase phase transition, in which changing a single parameter causes a localized (metal-insulator), a topological and parity-time symmetry breaking (energy) phase transition at the same time. This physical phenomenon is manifested in a time-driven dissipative quasicrystal. We realize our idea by coupling photon quantum walking in optical fiber loop. Our research highlights the interweaving of topological structure, symmetry breaking and mobility phase transition in non-Hermite quasicrystal synthetic materials. Our results can be applied to phase change devices, in which bulk transport and edge transport as well as energy or particle exchange with the environment can be predicted and controlled.

Quantum logic of spin qubits crossing surface coding threshold

Spin bit quantum logic beyond the threshold of surface code

Authors: Xiao Xue, maximilian Ras, Nodal Samkaladze, Brennan and Seth, Amir Samak, Giordano Scappucci, etc.

Link:

/articles/s 4 1586-02 1-04273-w

abstract

The high fidelity control of quantum bits is very important for the reliable realization of quantum algorithm and the realization of fault tolerance (the speed of error correction is faster than the speed of error occurrence). The core requirement of fault tolerance is expressed by error threshold. However, the actual threshold depends on many details, and the common target is a surface code with an error threshold of about 1%.

The fidelity of the two-bit gate is above 99%, which has always been the main goal of the semiconductor spin qubit. Due to advanced semiconductor technology, these qubits are expected to expand.

The research group reported a spin-based silicon quantum processor, and the fidelity of its single-bit gate and double-bit gate was higher than 99.5%, which was verified by gate set chromatography. When the crosstalk and idle error of adjacent qubits are included, the average single-bit gate fidelity remains above 99%.

Through this high-fidelity gate set, the research group completed the arduous task of calculating the molecular ground state energy by using the variable component codebook solver algorithm. Semiconductor qubits have surpassed the threshold of 99% fidelity of two-bit gates, and are in the era of high-noise medium-sized quantum devices, winning a place in fault tolerance and possible applications.

abstract

The high fidelity control of qubits is very important for the reliable implementation of quantum algorithms and the realization of fault tolerance (the ability to correct errors faster than errors occur). The core requirement of fault tolerance is expressed by error threshold. Although the actual threshold depends on many details, a common goal is that the error threshold of surface code is about 1%. The fidelity of double quantum gates above 99% has always been the long-term main goal of semiconductor spin qubits. These qubits are expected to be large-scale because they can make use of advanced semiconductor technology. Here, we report a spin-based silicon quantum processor with single qubit and double qubit gate fidelity, all of which are higher than 99.5%, extracted from gate set tomography. When the crosstalk and idle error of adjacent qubits are included, the average single qubit gate fidelity remains above 99%. Using this high-fidelity gate set, we have carried out the demanding task of calculating the ground state energy of molecules by using the variable component eigensolution algorithm. Semiconductor qubits have exceeded the 9 9% barrier of fidelity of two quantum gates. In the era of high-noise medium-scale quantum devices, semiconductor qubits are in a favorable position on the road to fault tolerance and possible application.

Fast universal quantum gate above fault-tolerant threshold in silicon

Fast universal quantum gate of silicon exceeding fault-tolerant threshold

Authors: Akito Nojiri, Takeda Kenta, Nakajima Takashi, Takashi Kobayashi, Amir Samak, Giordano Scappucci, etc.

Link:

/articles/s 4 1586-02 1-04 182-y

abstract

The fault-tolerant quantum computer that can solve difficult problems depends on quantum error correction. Surface code is one of the most promising error correction codes, which requires the fidelity of universal gates to exceed the error correction threshold of 99%.

Among many quantum bit platforms, only superconducting circuits, trapped ions and nitrogen vacancy centers in diamonds can meet this requirement. Electron spin qubits in silicon have great potential for large-scale quantum computers because of their nano-fabrication ability, but the fidelity of two-bit gates is limited to 98% because of their slow operation.

The research team realized 99.5% two-bit gate fidelity and 99.8% single-bit gate fidelity in silicon spin qubits by using micro-magnetic induction gradient field and fast electronic control coupling to tune two qubits. They determined the rotation speed and coupling strength of qubits, and realized the high fidelity gate robustly.

Using this universal gate set, the research team successfully implemented the Deutsch-Jozsa and Grover search algorithms. The results show that the fidelity of the universal gate exceeds the fault-tolerant threshold, and it is expected to realize an extensible silicon quantum computer.

abstract

The fault-tolerant quantum computer that can solve difficult problems depends on quantum error correction. One of the most promising error-correcting codes is surface code, which requires the fidelity of universal gates to exceed the error-correcting threshold of 99%. Among many quantum bit platforms, only superconducting circuits, trapped ions and nitrogen vacancy centers in diamonds meet this requirement. Electron spin qubits in silicon are particularly promising for large-scale quantum computers because of their nano-fabrication ability, but the fidelity of two quantum gates is limited to 98% because of their slow operation. Here, we show 99.5% double quantum gate fidelity and 99.8% single quantum gate fidelity in silicon spin qubit by using gradient field induced by micro-magnet and fast electrical control of adjustable double quantum bit coupling. We determine the rotation speed and coupling strength of qubits, and here we robustly realize high-fidelity gates. We use our universal gate set to implement the Deutsch-Jozsa and Grover search algorithms with high success rate. Our results prove that the universal gate fidelity exceeds the fault-tolerant threshold, and may make the scalable silicon quantum computer possible.

earth sciences

Historical glacier changes in Svalbard Island predict that the mass loss will double by 2 100.

In 2 100, the mass loss of glaciers in Svalbard will double.

Authors: Emily C. Goymen, Ward J. J. Vampell, Adam C. Maarouf, harald FAST EAAS &; Jack Kohler

Link:

/articles/s 4 1586-02 1-043 14-4

abstract

The melting of glaciers and ice sheets accounts for about one-third of the current sea level rise, exceeding the losses caused by the larger Greenland or Antarctic ice sheets. The spatial climate gradient of Svalbard in the Arctic is greater than the climate change in the next century currently predicted. It is a natural laboratory that can limit the climate sensitivity of glaciers and predict their response to future warming.

The research team linked the observation of historical glaciers with the observation of modern glaciers, and predicted that the rate of glacier thinning in 2 1 century would be more than twice that in 1936-20 10. Using the historical aerial image files of 1936 and 1938, they reconstructed the three-dimensional geometry of Svalbard 1594 glacier through photogrammetry.

The research team compared these reconstructed data with the elevation data of modern glaciers, and obtained a spatial model of material balance for more than 70 years, enabling people to quantify how variables such as temperature and precipitation control the loss of glaciers through the noise of interannual and interdecadal changes.

The research team found that the melting speed strongly depends on the temperature, that is, for every increase of 1 in the average temperature in summer, the normalized mass balance of the area decreases by 0.28 m water equivalent every year. Finally, the research team designed a time-space substitution scheme, combining their historical glacier observation with climate prediction, and made a first-class prediction of glacier changes in Svalbard in 2 1 century.

abstract

The melting of glaciers and ice sheets accounts for about one-third of the current sea level rise, which exceeds the mass loss of larger Greenland or Antarctic ice sheets. The spatial climate gradient of Svalbard Islands in the Arctic is greater than the expected time climate change in the next century, and it is a natural laboratory to suppress the glacier climate sensitivity and predict its response to future warming. Here, we link historical and modern glacier observation, and predict that the rate of glacier thinning in 2 1 century will be more than double that in 1936 to 20 10. Using the historical aerial image files of 1936 and 1938, we reconstructed the three-dimensional geometry of 1594 glaciers across Svalbard by using the photogrammetry of moving structures. We compare these reconstructed data with modern ice height data to obtain a spatial model of material balance over 70 years, which enables us to see through the noise of annual and ten-year changes and quantify how variables such as temperature and precipitation control ice loss. C the increase of the average temperature in summer is equivalent to the decrease of the area standardized mass balance by 0.28 m yr 1 water equivalent. Finally, we designed a space-time alternative scheme, combining our historical glacier observation with climate prediction, and made a first-order prediction of glacier changes in Svalbard in 2 1 century.