Welcome to our weekly digest of research highlights from the latest issue of Nature, published on 28th March 2024, Volume 627, Issue 8005. Let's dive into the cutting-edge discoveries and advancements featured in this issue.
Physics: Shock Flash from a Dusty Red Supergiant
Authors: Gaici Li, Maokai Hu, Wenxiong Li, Yi Yang, Xiaofeng Wang, Shengyu Yan, Lei Hu, Jujia Zhang, Yiming Mao, Henrik Riise, Xing Gao, Tianrui Sun, Jialian Liu, Dingrong Xiong, Lifan Wang, Jun Mo, Abdusamatjan Iskandar, Gaobo Xi, Danfeng Xiang, Lingzhi Wang, Guoyou Sun, Keming Zhang, Jian Chen, Weili Lin, Eliot Herman
Link: Nature Article
Abstract: Shock-breakout emission refers to the light produced when a shockwave, generated by the core-collapse explosion of a massive star, traverses its outer layers. Until now, such signals have typically been detected several hours post-explosion, with a few exceptions. The early evolution of light curves should offer insights into shock propagation, including explosion asymmetry and local environment, but a lack of multiwavelength observations has hindered progress. Here, we present immediate multi-band observations of a type II supernova (SN 2023ixf) in the M101 galaxy, commencing approximately 1.4 hours post-explosion. The progenitor star was a red supergiant with a radius of about 440 solar radii. The light curves underwent rapid changes, on the scale of 1-2 hours, and initially appeared dimmer and redder than predicted by models within the first few hours, attributed to an optically thick dust shell before its disruption by the shockwave. This suggests that the breakout event, and possibly the distribution of surrounding dust, may not have been spherically symmetric. The intricate cosmic surroundings of supernova 2023ixf
Authors: E. A. Zimmerman, I. Irani, P. Chen, A. Gal-Yam, S. Schulze, D. A. Perley, J. Sollerman, A. V. Filippenko, T. Shenar, O. Yaron, S. Shahaf, R. J. Bruch, E. O. Ofek, A. De Cia, T. G. Brink, Y. Yang, S. S. Vasylyev, S. Ben Ami, M. Aubert, A. Badash, J. S. Bloom, P. J. Brown, K. De, G. Dimitriadis, K. Zhang
Link: https://www.nature.com/articles/s41586-024-07116-6
Abstract: The early stages of a supernova (SN) offer insights into both its environment and the star that gave birth to it. When a star explodes in the vacuum of space, the initial burst of photons escaping its surface manifests as a brief, dazzling flare known as shock breakout, followed by a phase of emission as the supernova cools down.
However, when a star explodes within a dense and optically opaque distribution of circumstellar material (CSM), the first photons flee from the material surrounding the star, prolonging the duration of the initial flare to several days. During this time, the escaping emission indicates the heating of the photosphere. Early observations lacking ultraviolet (UV) data were unable to ascertain whether this early emission signifies heating or cooling, thus obscuring the nature of the early explosion event.
In this study, researchers present UV spectra of supernova 2023ixf in the galaxy Messier 101 (M101). By analyzing the UV data alongside a comprehensive array of multiwavelength observations, they temporally resolve the emergence of the explosion shock from the dense medium heated by the supernova's emission. Through this, they establish a dependable bolometric light curve, revealing that the shock emanates from a dense layer with a radius significantly larger than that of typical supergiants. Optomechanical Realization of the Bosonic Kitaev Chain
Abstract: The fermionic Kitaev chain, renowned for its topological Majorana zero modes, finds its bosonic counterpart manifested experimentally in a nano-optomechanical framework. Through parametric interactions, we induce beam-splitter coupling and two-mode squeezing among nanomechanical modes, mirroring the hopping and p-wave pairing dynamics of the fermionic scenario. This unique arrangement yields a plethora of remarkable phenomena in bosonic dynamics and transport.
We observe chiral amplification contingent upon quadrature, exponential growth in gain with system size, and remarkable sensitivity to boundary conditions. These traits are intrinsically tied to the distinct non-Hermitian topological essence of the bosonic Kitaev chain. By modulating interaction phases and amplitudes, we delve into the topological phase transition and unveil a diverse dynamical phase landscape.
Moreover, we demonstrate experimentally an exponentially augmented response to minute perturbations. These findings signify the emergence of a novel synthetic phase of matter characterized by bosonic dynamics devoid of fermionic analogs. Consequently, we establish a robust framework for exploring non-Hermitian topology and its utility in signal manipulation and sensing applications. High-Fidelity Spin Qubit Operation and Algorithmic Initialization Above 1 K
The encoding of qubits in semiconductor spin carriers has been recognized as a promising approach to a commercial quantum computer that can be lithographically produced and integrated at scale. However, the operation of the large number of qubits required for advantageous quantum applications will produce a thermal load exceeding the available cooling power of cryostats at millikelvin temperatures. As the scale-up accelerates, it becomes imperative to establish fault-tolerant operation above 1 K, at which the cooling power is orders of magnitude higher. Here we tune up and operate spin qubits in silicon above 1 K, with fidelities in the range required for fault-tolerant operations at these temperatures. We design an algorithmic initialization protocol to prepare a pure two-qubit state even when the thermal energy is substantially above the qubit energies and incorporate radiofrequency readout to achieve fidelities up to 99.34% for both readout and initialization. We also demonstrate single-qubit Clifford gate fidelities up to 99.85% and a two-qubit gate fidelity of 98.92%. These advances overcome the fundamental limitation that the thermal energy must be well below the qubit energies for the high-fidelity operation to be possible, surmounting a main obstacle in the pathway to scalable and fault-tolerant quantum computation. Climatology
Five million years of Antarctic Circumpolar Current strength variability
Authors: Frank Lamy, Gisela Winckler, Helge W. Arz, Jesse R. Farmer, Julia Gottschalk, Lester Lembke-Jene, Jennifer L. Middleton, Michèlle van der Does, Ralf Tiedemann, Carlos Alvarez Zarikian, Chandranath Basak, Anieke Brombacher, Levin Dumm, Oliver M. Esper, Lisa C. Herbert, Shinya Iwasaki, Gaston Kreps, Vera J. Lawson, Li Lo, Elisa Malinverno, Alfredo Martinez-Garcia, Elisabeth Michel, Simone Moretti, Christopher M. Moy, Xiangyu Zhao
Link: Read more
Abstract:
The Antarctic Circumpolar Current (ACC) represents the world's largest ocean-current system, influencing global ocean circulation, climate, and the stability of the Antarctic ice sheet. Researchers have documented variations in ACC strength from sediment cores in the southern Pacific Ocean. Contrary to expectations based on global cooling and increasing ice volume over the past 5.3 million years, there is no consistent long-term trend in ACC flow. Instead, there is a reversal on a million-year scale, with ACC strength increasing during periods of Pliocene cooling and decreasing during subsequent Early Pleistocene cooling.
This change in ACC dynamics corresponds to a reconfiguration of the Southern Ocean, altering the ACC's sensitivity to atmospheric and oceanic influences. The study links changes in ACC strength to 400,000-year eccentricity cycles, likely influenced by precessional changes in the South Pacific jet stream associated with variations in tropical Pacific temperatures. A connection emerges between weaker ACC flow, shifts in opal deposition towards the equator, and reduced atmospheric CO2 during glacial periods, notably during the Mid-Pleistocene Transition (MPT). The strongest ACC flow occurred during warmer intervals in the Plio-Pleistocene, suggesting a potential increase in ACC flow with future climate warming. Global Supply Chains Amplify Economic Costs of Future Extreme Heat Risk
Authors: Yida Sun, Shupeng Zhu, Daoping Wang, Jianping Duan, Hui Lu, Hao Yin, Chang Tan, Lingrui Zhang, Mengzhen Zhao, Wenjia Cai, Yong Wang, Yixin Hu, Shu Tao & Dabo Guan
Link: Read more
Abstract: Researchers have developed a disaster footprint analysis framework integrating climate, epidemiology, hybrid input-output, and computable general equilibrium global trade models to estimate the socio-economic impacts of heat stress by the mid-century. They considered health costs related to heat exposure, the value of heat-induced labor productivity loss, and indirect losses due to economic disruptions in the supply chain.
The study indicates that by 2060, under different shared socio-economic pathways, the global economic losses are projected to range from 0.6% to 4.6%, with health loss (37%-45%), labor productivity loss (18%-37%), and indirect loss (12%-43%) contributing significantly. Small and medium-sized developing countries are particularly affected, experiencing higher health loss in South-Central Africa (2.1 to 4.0 times the global average) and labor productivity loss in West Africa and Southeast Asia (2.0–3.3 times the global average). The impact of supply chain disruptions is extensive, notably affecting manufacturing-heavy countries like China and the USA, with economic losses soaring to 2.7% and 1.8%, respectively, by 2060.
