Science China Physics, Mechanics & Astronomy最新文献

For decades, efforts to shape acoustic waves focused on fixed metamaterials and static phase masks, leaving their internal state evolution largely untouchable. Here, we introduce an all-classical platform that unlocks real-time, Bloch sphere control of an acoustic two-level system, bringing the full arsenal of quantum-style coherent protocols to the realm of sound. Using a programmable electro-acoustic architecture, we implement independent and synchronized modulation of onsite detuning, coupling strength, and dissipation—enabling full Bloch-sphere trajectory steering. On this basis, we realize quantum-inspired control protocols including Rabi oscillations, Ramsey interference, Floquet modulation, and spin echo sequences, tracking amplitude and phase evolution of acoustic states in real time. Our approach establishes a new paradigm for wave-based control, bridging classical acoustics with quantum coherent protocols, and opens new opportunities for programmable sound field engineering, information storage, and analog simulation of gauge field dynamics.

The Chinese Space Station Survey Telescope (CSST) is an upcoming Stage-IV sky survey telescope, distinguished by its large field of view (FoV), high image quality, and multi-band observation capabilities. It can simultaneously conduct precise measurements of the Universe by performing multi-color photometric imaging and slitless spectroscopic surveys. The CSST is equipped with five scientific instruments, i.e., Multi-band Imaging and Slitless Spectroscopy Survey Camera (SC), Multi-Channel Imager (MCI), Integral Field Spectrograph (IFS), Cool Planet Imaging Coronagraph (CPI-C), and THz Spectrometer (TS). Using these instruments, CSST is expected to make significant contributions and discoveries across various astronomical fields, including cosmology, galaxies and active galactic nuclei (AGN), the Milky Way and nearby galaxies, stars, exoplanets, Solar System objects, astrometry, and transients and variable sources. This review aims to provide a comprehensive overview of the CSST instruments, observational capabilities, data products, and scientific potential.

The origin of supermassive black holes (SMBHs) is a pivotal problem in modern cosmology. This work explores the potential of the Taiji-TianQin space-borne gravitational-wave (GW) detector network to identify the formation channels of massive black hole binaries (MBHBs) at high redshifts (z ≳ 10). The network substantially improves detection capability, boosting the signal-to-noise ratio by a factor of 2.2–3.0 (1.06–1.14) relative to TianQin (Taiji) alone. It increases the detection rate of MBHBs formed from light seeds (LS) by more than 2.2 times and achieves over 96% detection efficiency for those originating from heavy seeds (HS). Furthermore, the network enables component mass estimation with relative uncertainties as low as ∼ 10⁻⁴ at the 2σ level. These improvements facilitate the assembly of a well-constrained population sample, allowing robust measurement of the fractional contributions from different formation pathways. The network achieves high precision in distinguishing between LS and HS origins (7.4% relative uncertainty at 2σ) and offers moderate discrimination between delay and no-delay channels in HS-origin binaries (24%). However, classification remains challenging for delay versus no-delay scenarios in LS-origin systems (58%) due to significant population overlap. In conclusion, the Taiji-TianQin network will serve as a powerful tool for unveiling the origins of SMBHs through GW population studies.

Chip-scale quantum magnetometers featuring both ultra-high sensitivity and uniform spin polarization are highly desired for practical applications and have been diligently pursued. However, the fulfillment of such capabilities for quantum magnetometers typically necessitates a separate heating unit, bulky reflector, and beyond, severely impeding on-chip integration and batch fabrication of these quantum devices. Herein, we present a novel paradigm for the wafer-level fabrication of ultra-sensitive chip-scale quantum magnetometer, which is enabled by integrating a highly reflective mirror and a temperature-controlled component on the optically transparent windows of the MEMS atomic vapor cell, thereby providing a genuinely all-in-one atomic vapor cell with a temperature stability better than ±5 mK at up to 200°C as well as a reflectivity of 95% at Rb D1 transition wavelength. With the as-developed on-chip atomic vapor cell with internal dimensions of Φ 3×1.5 mm³, we configured a chip-scale single-beam atomic magnetometer with a sensitivity floor of about 15 fT/Hz^1/2, along with a theoretically more homogeneous spin polarization distribution. We envision that the proposed chip-scale integration solution paves a concrete route for batch manufacturing and widespread application of quantum magnetometers.

Quantum two-way time transfer (Q-TWTT) leveraging energy-time entangled biphotons has achieved sub-picosecond stability but faces fundamental distance limitations due to the no-cloning theorem’s restriction on quantum amplification. To overcome this challenge, we propose a cascaded Q-TWTT architecture employing relay stations that generate and distribute new energy-time entangled biphotons after each transmission segment. Theoretical modeling reveals sublinear standard deviation growth (merely (sqrt{N}times) increase for N × equidistant segments), enabling preservation of sub-picosecond stability over extended distances. We experimentally validate this approach using a three-station cascaded configuration over 2×100 km fiber segments, demonstrating strong agreement with theory. Utilizing independent Rb clocks at end and relay stations with online frequency skew correction, we achieve time stabilities of 3.82 ps at 10 s and 0.39 ps at 5120 s. The consistency in long-term stability between cascaded and single-segment configurations confirms high-precision preservation across modular quantum networks. This work establishes a framework for long-distance quantum time transfer that bypasses the no-cloning barrier, providing a foundation for future quantum-network timing infrastructure.

The Unruh effect predicts an astonishing phenomenon that an accelerated detector would detect counts despite being in a quantum field vacuum in the rest frame. Since the required detector acceleration for its direct observation is prohibitively large, recent analog studies on quantum simulation platforms help to reveal various properties of the Unruh effect and explore the not-yet-understood physics of quantum gravity. To further reveal the quantum aspect of the Unruh effect, analogous experimental exploration of the correlation between the detector and the field, and the consequences for coherent quantum trajectories of the detector without classical counterparts, are essential steps but are currently missing. Here, we utilize a laser-controlled trapped ion to experimentally simulate an oscillating detector coupled with a cavity field. We observe joint excitation of both the detector and the field in the detector’s frame, coincide with the coordinated dynamics predicted by the Unruh effect. Particularly, we simulate the detector moving in single and superposed quantum trajectories, where the latter case shows coherent interference of excitation. Our demonstration reveals properties of quantum coherent superposition of accelerating trajectories associated with quantum gravity theories that have no classical counterparts, and may offer a new avenue to investigate phenomena in quantum field theory and quantum gravity. We also show how a generalization of the method and results in this work may be beneficial for direct observation of the Unruh effect.

Current gravitational-wave detectors have achieved remarkable sensitivity around 100 Hz, enabling ground-breaking discoveries. Enhancing sensitivity at higher frequencies in the kilohertz (kHz) range promises access to rich physics, particularly the extreme conditions during the merger stage of binary neutron stars. However, the high-frequency sensitivity of Michelson-based interferometers is fundamentally limited by their linear optical cavities, which are optimized for low-frequency signal enhancement. A new configuration employing an L-shaped optical resonator was proposed to overcome this limitation, offering exceptional sensitivity in the kHz band. As a pathfinder, the 12-meter prototype at Beijing Normal University is designed to demonstrate the sensing and control schemes of this new kHz detector configuration and to explore its performance in the high-power regime with suspended optics. Beyond its primary scientific goal, the prototype also offers potential sensitivity in the megahertz (MHz) range, potentially enabling constraints on exotic sources. This paper presents an overview of the prototype, including its optical design and current development status of key components.

In this study, we propose an effective strategy for selecting alloying elements to suppress hydrogen diffusion in γ-uranium (γ-U) based on the first-principles investigation of the Niobium (Nb) influences on hydrogen diffusion behavior. The simulation results show that the substitution of Nb in the body-centered cubic (bcc) lattice of γ-U significantly reduces the hydrogen diffusion rate, driven by two key factors: the thermodynamic stabilization of the γ-U bcc lattice and Nb’s strong hydrogen trapping effect. Diffusion energy pathway and electronic structure analyses reveal the presence of energy wells around Nb atoms, causing hydrogen to form cage-like diffusion pathways centered on Nb atoms, which effectively restricts long-range hydrogen diffusion in γ-U. Although Nb’s hydrogen trapping ability decreases at higher hydrogen concentrations, it still plays a crucial role in preventing the nucleation of UH₃. Based on these findings, we propose a strategy for predicting hydrogen diffusion kinetics in a series of U-X (X = Ti, Tc, Nb, Mo, Re, Zr, In, Tl) alloys using first-principles static calculations, and establish a near-linear correlation between diffusion energy barriers, X-H bond lengths, and alloy formation energies. Our study underscores the importance of first-principles calculations in selecting suitable alloying elements to regulate hydrogen diffusion in uranium alloys, offering valuable insights with significant implications for engineering applications.

Time-delay interferometry (TDI) is essential for suppressing laser frequency noise in space-based gravitational wave (GW) observatories such as LISA. However, current second-generation TDI schemes often exhibit undesirable null frequencies and require long delay spans, which can impair data analysis performance. In this work, we introduce an alternative TDI configuration—PD4L—designed to minimize null frequencies and operate with a shorter effective time span. Constructed by synthesizing two distinct first-generation TDI schemes, PD4L achieves a delay span of 4L (where L is the arm length), half that of the standard Michelson and hybrid Relay configurations. We assess PD4L’s performance by evaluating the spectral stability of instrumental noise via arm-length derivatives, simulating chirping GW signals from coalescing massive black hole binaries, and comparing waveform responses. Parameter estimation is performed in the frequency domain, and noise characterization is examined under realistic orbital dynamics. As demonstrated by the comparisons, the compact structure of PD4L offers several advantages: (1) reduced data margins at segment boundaries, (2) mitigated aliasing effects in the high-frequency regime, and (3) shortened signal tails arising from extended delay spans. Additionally, PD4L’s null channels exhibit the same minimal null frequencies as its science channels, while maintaining greater spectral stability than other null streams. Overall, PD4L improves parameter estimation accuracy at high frequencies and supports reliable noise characterization over observation periods of up to four months. These results highlight PD4L as a compact and effective alternative for future TDI implementations, especially in high-frequency GW data analysis for LISA-like missions.