Quantum coherence plays a fundamental role in driving ultrafast molecular dynamics, but its observation in highly excited states of polyatomic molecules remains rare. Here, using time-resolved photoelectron spectroscopy (TRPES), we report the observation of coherent vibrational quantum beating in the predissociation dynamics of the SF6 molecule, triggered by a 14.1-eV extreme ultraviolet laser pulse. We observe the temporal oscillation profile of TRPES intensity with a period of 318 fs, arising from the interference between different vibrational states separated by 0.013 eV. Supported by ab-initio calculations of potential-energy surfaces, we identify the vibrational states responsible for these observations and extract the lifetimes of both coherences and populations. This work opens pathways to understand and ultimately control the role of coherence in photochemical processes of complex molecular systems.

β3-Adrenergic receptors (β3-ARs), as a subclass of G protein-coupled receptors (GPCRs), play a pivotal role in regulating oxidative stress. However, the dynamic interplay between their microenvironmental fluctuations and glioma mechanisms remains poorly understood. Here, we report the development of GSHP, a blood-brain barrier (BBB)-permeable probe that simultaneously visualizes β3-ARs and reversibly monitors the surrounding redox status in real-time. This dual-responsive probe enables reversible dynamic imaging of redox homeostasis around β3-ARs in living cells under stress conditions, providing direct visual evidence for redox adaptation. Using GSHP for high-throughput screening, we identified and validated baicalin as a potent β3-AR natural inhibitor that induces glutathione depletion and triggers oxidative stress-mediated apoptosis via the Gαi/o-extracellular signal-regulated kinase (ERK)-nuclear factor erythroid 2-related factor 2 (Nrf2)-glutamate-cysteine ligase catalytic subunit (GCLc) signaling pathway in U251 glioblastoma cells. In orthotopic U251 glioma mouse models, GSHP penetrated the brain and enabled dual-channel imaging of β3-AR overexpression and redox imbalance in vivo, allowing for effective glioma discrimination and demonstrating its potential for therapeutic monitoring. GSHP thus serves as a versatile platform for studying β3-AR-related redox biology and facilitating therapeutic discovery in brain diseases.

Ground-state cooling of mechanical resonators in cavity magnomechanical (CMM) systems is critical for quantum technologies, but is fundamentally limited by intrinsically weak magnon-phonon coupling. Conventional strong-driving-based coupling amplification introduces excess quantum noise, while pioneering squeezing-assisted CMM cooling schemes rely on strong driving, using squeezing to suppress heating noise, leaving the weak-coupling bottleneck unaddressed. Here, we propose a scheme using magnon squeezing as the core mechanism to enhance effective magnon-phonon coupling via tuning squeezing strength and phase, eliminating the need for intrinsic coupling enhancement or excessively strong driving beyond the linearization regime. Theoretical analysis shows that a red-detuned squeezed magnon mode markedly boosts the net cooling rate, enabling ground-state cooling at higher bath temperatures, with performance further optimized by reducing magnon dissipation. This approach amplifies magnomechanical coupling while avoiding detrimental strong-driving effects, providing a practical, low-noise route to efficient quantum cooling in CMM systems.

Unlike in the liquid phase, the debate of whether and how hydrogen-bonded structures exist in neutral ammonia dimer (NH3)2 in the gas phase has been ongoing for several decades. Here, we distinguish the structures of neutral ammonia dimers with and without hydrogen bonds by photoionization because the ions inherit initial structures from the neutral dimers and lead to significantly different Coulomb explosion channels in our pump-probe experiment, i.e., the direct dissociation (NH3+ + NH3+) and indirect dissociation with proton migration (NH2+ + NH4+). With quantum chemical and molecular dynamics simulation, we showcase that these two different Coulomb explosion channels originate from the ammonia dimer cations with different structures. The dimer cations without hydrogen bonds correlate with the direct Coulomb explosion channel. In contrast, dimer cations with hydrogen bonds are likely to undergo ultrafast proton migration in ∼48 fs, which has no potential barrier and correlate with the indirect dissociation channel in the Coulomb explosion. The 48 fs characteristic time is used to exclude the slower indirect dissociation initiated from non-H-bonded cations. Our work demonstrates a highly sensitive approach to probe weakly bonded and fluxional structures of gas-phase molecular clusters by utilizing both channel and time resolutions of Coulomb explosion.

Quantum tomography (QT) has found broad applications across multiple disciplines, such as atomic and molecular physics, quantum optics, quantum computing, and quantum information. Here, we provide a comprehensive overview of QT applied to atoms and molecules, which enables the full reconstruction of quantum states when combined with state-of-the-art ultrafast imaging techniques, such as velocity map imaging, photoelectron spectroscopic imaging, and ultrafast electron diffraction imaging. QT reconstructs the quantum states for a variety of ultrafast molecular dynamics processes, including photoionization, dissociation, rotational wave packet alignment, and electronic state internal conversion. By providing fully quantum-mechanical descriptions, the tomographically reconstructed quantum states unveil a range of nonclassical phenomena, such as the spatial interference of wave packets, Dyson orbitals of photoionized molecules, and entanglement between parent ions and emitted electrons in multichannel photoionization.

Cellular senescence contributes to tumor recurrence by fostering a pro-tumorigenic microenvironment after therapy. While SA-β-gal serves as a widely adopted biomarker of senescence, its inadequate specificity impedes the precision with which senolytic therapies can be directed. Here, we designed and developed a theranostic probe named DMTP-1 to target monoamine oxidase A (MAO-A), an enzyme that is upregulated in senescent tumor cells. Upon MAO-A activation, DMTP-1 is converted to a cationic product, ADMTP-1, which exhibits aggregation-induced emission (AIE) for imaging and generates reactive oxygen species (ROS) under light for photodynamic therapy (PDT). Cellular studies demonstrate that the fluorescence signal and PDT efficacy of DMTP-1 are markedly enhanced in MAO-A-overexpressing senescent tumor cells, enabling image-guided elimination of these cells. Moreover, DMTP-1 shows potent photodynamic activity in 3D multicellular tumor spheroids and enables clear visualization of senescence-associated MAO-A upregulation in a zebrafish senescence model. This MAO-A-activated probe enables specific detection and eradication of therapy-induced senescent tumor cells, offering a targeted strategy for senolytic intervention.

The emergence of X-ray free-electron lasers (XFELs) with attosecond capabilities has opened unprecedented opportunities for probing ultrafast spin dynamics in molecules. Magnetic X-ray scattering (MXS), while well-established in condensed matter physics, remains nascent for isolated molecules. Here we review the theoretical framework and computational methodology for molecular MXS on femtosecond and attosecond timescales. Using circular dichroism to separate spin-dependent contributions from dominant charge scattering, MXS enables direct probing of spin-dependent dynamics during ultrafast processes. We demonstrate these capabilities through three paradigmatic examples: femtosecond spin-orbit beating in NO molecules, sub-femtosecond singlet-triplet oscillations in core-excited TiCl4, and Berry phase detection during CH2OH photodissociation. We connect this molecular framework to established condensed-matter magnetic X-ray techniques and compare with the recent proposal of time-resolved XMCD for molecular photodynamics. Together, these theoretical and computational developments position molecular MXS as a powerful tool for understanding spin-resolved electron dynamics inaccessible by other ultrafast techniques.

Recovering the rotational density matrix of a molecular ensemble from time-resolved angular distributions is central to understanding ultrafast rotational dynamics, yet the inverse problem is severely underdetermined. We analyze the forward operator that maps the density matrix of laser-aligned symmetric-top molecules to the angular distribution retrieved in pump-probe experiments and demonstrate through singular value decomposition that 74%-88% of the real density matrix unknowns lie in the null space for maximum angular momentum quantum numbers Jmax = 2-5. This rank deficiency is intrinsic to the measurement geometry and imposes a linear lower bound on reconstruction error: the minimum-norm least-squares (pseudoinverse) solution sets all null-space components to zero, establishing the best achievable error for any linear, unbiased estimator. Nonlinear constraints-positive semidefiniteness, trace conservation, and block symmetries-partially recover null-space information, but the residual error grows with Jmax, reaching 15%-44% for Jmax = 5. We present a two-stage pipeline in which a convolutional neural network trained on simulated data provides a warm start for the fast iterative shrinkage-thresholding algorithm. For both CF3I and CH3Cl across Jmax = 2-6, this approach reduces the Frobenius reconstruction error by 80%-99% relative to optimization from thermal equilibrium, maintaining stable errors of 0.5%-1.1% as Jmax increases. The pipeline is robust to data noise down to a 20 dB signal-to-noise ratio and operates ten times faster than the baseline and outperforms the maximum-entropy approach by a factor of 15-39×. The classical iterative quantum tomography algorithm becomes numerically unstable for Jmax ≥ 4, whereas the proposed method converges reliably at all tested truncation levels.

We theoretically investigated the rotational-vibrational (ro-vibrational) spectrum of the NH2 molecule in the X~2A″ and A~2A' electronic states. Because the ground electronic state X~2A″ and the first excited state A~2A' have nonlinear equilibrium geometries, the Renner-Teller (RT) effect plays a significant role in the ro-vibrational spectrum. By introducing the RT effect as an effective coupling potential of the X~2A″ and A~2A' states, the ro-vibrational spectra at different total angular momentum quantum numbers are calculated with the generalized Laguerre discrete variable representation (LDVR), Laguerre-Morse DVR (LMDVR), and Jacobi DVR (JDVR). Additionally, we conduct a comparative analysis of the efficiency of Laguerre, Laguerre-Morse, Jacobi, and conventional sine DVR in calculating the ro-vibrational spectra. The results of the ab initio calculations are presented in this work as well as the data and code for the potential energy surface (PES) part of the Hamiltonian with the RT effect.

Ultrashort XUV pulses of the Free-Electron-LASer in Hamburg (FLASH) were used to investigate laser-induced fragmentation patterns of the prototypical chiral molecule 1-iodo-2-methyl-butane (C_5H_11I) in a pump-probe scheme. Ion velocity-map images and mass spectra of optical-laser-induced fragmentation were obtained for subsequent FEL exposure with photon energies of 63 eV and 75 eV. These energies specifically address the iodine 4d edge of neutral and singly charged iodine, respectively. The presented ion spectra for two optical pump-laser wavelengths, i.e., 800 nm and 267 nm, reveal substantially different cationic fragment yields in dependence on the wavelength and intensity. For the case of 800-nm-initiated fragmentation, the molecule dissociates notably slower than for the 267-nm pump. The results underscore the importance of considering optical-laser wavelength and intensity in the dissociation dynamics of this prototypical chiral molecule that is a promising candidate for future studies of its asymmetric nature.

Aqueous neuromorphic devices using essential biological mechanisms have recently appeared as promising candidates for high-level neurosynaptic emulation. Towards the important functionality of motion recognition, while conventional solid-state neuromorphic vision sensors have made significant progress, aqueous motion recognition based on biochemical transmission remains challenging. Taking inspiration from biology, here we report an organic photoelectrochemical transistor biosensor capable of parallel emulation of visual adaptation and memory towards biochemically mediated motion recognition in a real scene. Based on the rational design and implementation of photoelectrochemical events, two artificial Magno and Parvo pathways are emulated to produce visual adaptation and memory in aqueous conditions, respectively. Dynamic and static visual information could be correspondingly processed and applied for integrated image filtering in a real scene and recognition of moving objects by artificial neural networks.

The use of short photoelectron pulses, pioneered in the 1980s, opened up the possibility of studying structural dynamics with high spatiotemporal resolution. The combination of nano-pico-femtosecond lasers with electron-based technology has become extremely fruitful for observing the behavior of atoms and molecules on their natural length and time scales. In imaging mode, this concept soon led to the creation of 4D transmission electron microscopy. In the electron diffraction mode, the achievement of ultrabright electron sources provided a unique opportunity to shoot molecular movies with atomic resolution. These sources are at their fundamental space charge limit with sufficient brightness to literally light up atomic motions. The high sensitivity of this approach, combined with low radiation damage, made it possible to atomically resolve reaction dynamics with nanograms of material. In contrast to the X-ray free electron lasers (XFELs), the development of ultrabright electron sources made it possible to conduct experiments on very thin films of promising materials in small-scale facilities in standard laboratories. The extension to quantum tomography has recently opened a new page in the study of matter using short electron bunches. Here we review the development of ultrafast transmission electron microscopy and diffraction techniques that enable detection of structural dynamics on the primary timescales.

Spontaneous symmetry breaking, driven by nonadiabatic electron-nuclear coupling, can lead to geometric complexity in molecules and solids. While structural distortion from symmetry breaking occurs in femtoseconds, the timescale to lift electronic state degeneracy has remained elusive. We use the vibrationally resolved attosecond chronoscope to capture the electronic symmetry breaking induced by the Renner-Teller effect in bent CO2 molecules after photoionization by an extreme ultraviolet photon by measuring attosecond ionization delays. Relative photoionization delays between the four cation states are observed, with vibrational state-dependent delays, we analyze the evolution of the degenerate [Formula: see text] state to the nondegenerate A' and A″ states due to molecular bending. With the help of theoretical analysis, we show that the relative photoionization delays of up to 72 as between the vibrational levels originate from the symmetry breaking-induced shape resonance. This study offers fundamental insights by resolving the coupled electron and structural dynamics simultaneously.

Chemistry involves dynamics that transform chemical structures from one form to another. However, among the vast milieu of quantum vibrations in a molecule, it boils down to a few key motions that drive the system across the transition state. It is the anharmonicity at the transition state or barrier-crossing region that couples normal modes, leading to localized motions and reduced dimensionality. The interplay of strongly anharmonic local modes collectively drives the system across the barrier-crossing region, forming a photoproduct. Ultrafast broadband transient absorption spectroscopy has revealed the effect of reduced dimensionality in a prototypical ring-closing reaction in fulgide single crystals. The relatively large anharmonicity at the reactive crossing and the strong reaction forces experienced during the chemical transformation provide a significant driving force for the vibrational modes, revealing a new mechanism of coherent vibrational energy transfer between molecular modes. This effect is observed as a non-impulsive growth of modulation in the amplitude of an 80 cm-1 mode coupled to the reaction coordinate. Our study sheds light on the lattice-coupled reaction dynamics owing to specific system-bath interactions and provides new insight into utilizing lattice alignment for chemical transformation in a solid-state crystalline environment.

Crystalline undulator radiation(CUR)is emitted by charged particles channeling through a periodically bent crystal.We show that entangled high-energy photons of the order of 100 MeV can be generated from CUR and obtain the quantum entanglement properties of the double-photon emission of CUR with a nonperturbative quantum field theory.We demonstrate that the crystalline undulator(CU)can induce a 3D free-electron lattice with premicrobunched electrons,and the resulting free-electron lattice can enhance the entangled high-energy photon emission for certain angles by phase matching.We also examine the effects of demodulation and dechanneling during the electron beam channeling process,and show the dependence of the dechanneling and demodulation lengths on the undulator parameters.

The demand for deep human-machine fusion propels the development of artificial neurons. However, emulating the neuronal spiking in aqueous environments remains challenging. Metal-organic frameworks (MOFs) have recently shown promise in neuromorphic engineering compatible with aqueous operation. Here, we report a MOF neuron with real neurotransmitter-dopamine (DA)-tunable spikes for the first time. Based on the DA mediation, some sophisticated neuronal functions, including integration-and-firing, synaptic facilitation-induced spike broadening and DA-tunable spiking number and width, were mimicked. DA-mediated spikes in this MOF neuron were further implemented to exquisitely control peripheral equipment. This work introduces the concept of a MOF neuron interfaced with a real neurotransmitter in fluids, providing a new perspective for artificial neuron development.

The transfer of population between two intersecting quantum states is the most fundamental event in many dynamical processes in physics, chemistry, biology, and material science. Any two-state description of such processes requires population leaving one state to instantaneously appear in the other. We show that coupling to additional states, present in all real-world systems, can cause a measurable delay in population transfer. Using attosecond spectroscopy supported by quantum-chemical calculations, we measure a delay of 1.46 ± 0.41 fs at a charge-transfer crossing in CF 3 I + , where an electron hole moves from the fluorine atoms to iodine. Our measurements also resolve the other fundamental quantum-dynamical processes involved in the charge-transfer reaction: a vibrational rearrangement time of 9.38 ± 0.21 fs (during which the vibrational wave packet travels to the state crossing) and a population-transfer time of 2.3–2.4 fs. Our work shows that delays in population transfer readily appear in otherwise-adiabatic reactions and predicts them to be on the order of a single-femtosecond for molecular valence-state crossings. These results have implications for many research areas, such as atomic and molecular physics, charge transfer, or light harvesting.

A key challenge in ultrafast science has been to directly track the coupled motions of electrons and nuclei in real space and real time. This Letter presents a significant step toward this goal by demonstrating the feasibility of time-resolved real-space tracking of valence electron and hydrogen dynamics during the photodissociation of ammonia (NH_{3}) using MeV ultrafast electron diffraction. It is demonstrated that the enhanced temporal resolution, in conjunction with the analysis of the charge-pair distribution function, enables the disentanglement of the correlated motion of valence electrons and hydrogens in a photoexcited ammonia molecule. The methodology employed in this Letter, which utilizes the charge-pair distribution function from ultrafast electron scattering to retrieve intertwined electron and nucleus dynamics, may open up new opportunities in the study of quantum dynamics for a wide range of molecules.

The study on aqueous reservoir computing (RC) has just come into being. Nevertheless, aqueous RC still faces significant challenges. Recently, with the participation of real biological receptors, aqueous neuromorphic engineering is promising to emulate the intricate human brain more closely due to their synaptic resemblance in electrolytes. In this work, biologically switchable volatility and nonvolatility are first explored for real neurotransmitter glutamate-mediated aqueous RC application, which is based on rational synergy between glutamate oxidase catalytic chemistry and porphyrin-based metal-organic framework/tungsten oxide (PCN-224/WO3) photogate in the newly emerged organic photoelectrochemical transistor. As a proof of concept, the glutamate-mediated RC is then developed and explored for image recognition. These results have of potential for advancing real neurotransmitter-mediated aqueous RC toward in-biology application, which are also envisaged to promote bioinspired algorithm-hardware codesign in future aqueous neuromorphic engineering.

Neuromorphic perception capable of multisensory integration (MSI) in electrolytes is important but remains challenging. Here, the aqueous implementation of artificial MSI is reported based on the newly emerged organic photoelectrochemical transistor (OPECT) by representative visual (light)-gustatory (sour) perception. Under the co-modulation of light and H+/OH-, multisensory synaptic plasticity and several typical MSI characteristics are mimicked, including "super-additive response," "inverse effectiveness effect" and "temporal congruency." To demonstrate its potential usage, different types of multisensory associative learning and corresponding reflex activities are further emulated. The chemical MSI system is also utilized to control artificial salivation by a closed loop of real-time perception, processing, integration, and actuation to emulate the biological responses toward external stimuli. In contrast to previous solid-state operations, this work offers a new strategy for developing neuromorphic MSI in aqueous environments that are analogous to those in biology.