The uniqueness of purifications of quantum states on a system $A$ up to local unitary transformations on a purifying system $B$ is central to quantum information theory. We show that, if the two systems are modeled by commuting von Neumann algebras $M_A$ and $M_B$ on a Hilbert space $\mathcal{H}$, then uniqueness of purifications is equivalent to Haag duality $M_A=M_B^{\prime }$. In particular, the uniqueness of purifications can fail in systems with infinitely many degrees of freedom—even when $M_A$ and $M_B$ are commuting factors that jointly generate $B(\mathcal{H})$ and hence allow for local tomography of all density matrices on $\mathcal{H}$. We present a simple argument showing that the uniqueness of purifications, and, hence, Haag duality, fail in ground state sectors of topologically ordered models at renormalization group fixed points on infinite two-dimensional lattices, partitioned into the union of two spatially separated cones and its complement.

Recent advancements in generalized symmetries have drawn significant attention to gapped phases of matter exhibiting novel symmetries, such as noninvertible symmetries. By leveraging the duality transformations, the classification and construction of gapped phases with noninvertible symmetry can be mapped to those involving conventional group symmetries. We demonstrate this approach by classifying symmetry-protected-topological phases with a broad class of noninvertible symmetries in arbitrary spacetime dimensions. Our results reveal new classifications that extend beyond those based on group symmetries. Additionally, we construct lattice models in $(1+1)D$ and $(2+1)D$ that realize these new phases and explore their anomalous interfaces.

We show that a QCD dilaton field, whose vacuum expectation value sets the strong coupling, can render the quantum chromodynamic (QCD) confinement transition first order. The QCD dilaton is cosmologically attracted to a false vacuum at weak coupling in the early Universe. Quantum tunneling toward the true vacuum triggers prompt chiral symmetry breaking and confinement of QCD, leading to detonating bubbles of the hadronic phase. We find that plasma sound waves produced by this dilaton-induced, first-order QCD phase transition generate a stochastic gravitational wave signal strikingly similar to the recently detected gravitational wave background from pulsar timing arrays. We briefly comment on how this theory can be probed through collider experiments and cosmology.

We experimentally demonstrate that individual molecules of formic acid are chiral even when they are in the vibronic ground state, which has a planar equilibrium structure. We ionize the C $1s$ shell of the molecule and record the photoelectron in coincidence with positively charged fragments. This provides two consecutive measurements of the structure of one molecule, the first by photoelectron diffraction imaging and the second by Coulomb explosion imaging. We find that both measurements show the same handedness of the specific molecule. The phenomenon of being achiral on average but chiral at the level of individual molecules is general to prochiral molecules and is a consequence of the three-dimensional zero-point delocalization of the nuclei in the vibrational ground state.

Non-Abelian physics, originating from noncommutative sequences of operations, unveils novel topological degrees of freedom. In photonics, significant efforts have been devoted to developing reconfigurable non-Abelian platforms, serving both as classical testbeds for non-Abelian quantum phenomena and as programmable systems that harness topological complexities. Here, we establish topological spinor lattices for non-Abelian programmable photonics. We design a building block for reconfigurable unitary coupling between pseudospin resonances, achieving a universal set of rotation gates through the coupling loop. The lattice assembly of the building blocks enables the emulation of the extended quantum Hall family. We reveal the emergence of a non-Abelian interface even when the bulks are Abelian, which allows the topologically trivial engineering of topologically protected edge states. We also define the braid group for pseudospin observables, demonstrating non-Abelian braiding and the Yang-Baxter relations. Our results pave the way for realizing a reconfigurable emulator for Abelian and non-Abelian topological phenomena.

Topological node of electronic bands can carry emergent charge degree of freedom such as the Berry curvature monopole of the Weyl semimetals, which results in intriguing transport and optical phenomena. In this Letter, we discuss the existence of the hidden “Dirac charge” and its detection via the photocurrent response in antiferromagnetic (AFM) Dirac semimetals. In light of the Berry curvature defined in the spin and spin-charge-mixed parameter space, we identify Dirac charges as sources or sinks of the Berry curvature in the generalized parameter space. We demonstrate that this Dirac charge can be detected via the photocurrent driven by the spin-charge-coupled motive force. By using real-time simulation, we find that the Dirac charge plays a significant role in the photocurrent generation in AFM Dirac semimetals. This Letter reveals the hidden property of the Dirac points in AFM Dirac semimetals.

Mechanical degrees of freedom very weakly couple to spins in semiconductors. The inefficient coupling between phonons and single electron spins in semiconductor quantum dots (QDs) hinders their integration into on-chip acoustically coupled quantum hybrid systems. We propose a hybrid acousto-optical spin control method that circumvents this problem and effectively introduces acoustic spin rotation to QDs, complementing their rich couplings with external fields and quantum registers. We show that combining continuous-wave detuned optical coupling to a trion state and acoustic modulation results in spin rotation around an axis defined by the acoustic field. The optical field breaks spin conservation, allowing phonons to drive transitions between disrupted spin states when at resonance with the Zeeman frequency. Our method is compatible with pulse sequences that mitigate quasistatic noise effects, which makes trion recombination the primary limitation to gate fidelity under cooled nuclear-spin conditions. Numerical simulations indicate that spin rotation fidelity can be very high, if the trion lifetime is long and Zeeman splitting is sufficiently large, with a currently feasible 50 ns lifetime and 44 GHz splitting giving 99.9% fidelity. Applying our advancement could enable acoustic QD spin state transfer to diverse solid-state systems and transduction between acoustic, optical, and microwave domains, all within an on-chip integration-ready setting.

We present a joint theoretical and experimental investigation of the isomerization dynamics of doubly ionized acetonitrile $[{\mathrm{H}}_3\mathrm{C}─\mathrm{C}\equiv \mathrm{N}{]}^{2+}$ in the gas phase. Molecular dynamics simulations show that the dication retains its linear geometry for a few hundred femtoseconds (fs) before undergoing a fast cyclization process, where the carbon and nitrogen atoms arrange into a triangular geometry. It occurs in less than 30 fs, a time comparable to or even shorter than that required for the migration of the much lighter hydrogen atoms. As a result, the dication later adopts an almost irreversible linear isonitrile ($\mathrm{C}─\mathrm{N}─\mathrm{C}$) configuration, where the positions of the neighboring nitrogen and carbon atoms are swapped with respect to their initial arrangement. These findings are compatible with the outcomes of fs pump-probe experiments in which the produced charged fragments are detected in coincidence as a function of the pump-probe delay via Coulomb explosion imaging.

Dissipative quantum chaos plays a central role in the characterization and control of information scrambling, nonunitary evolution, and thermalization, but it still lacks a precise definition. The Grobe-Haake-Sommers conjecture, which links Ginibre level repulsion to classical chaotic dynamics, was recently shown to fail [Phys. Rev. Lett. 133, 240404 (2024)]. We properly restore the quantum-classical correspondence through a dynamical approach based on the von Neumann entropy (VNE) and out-of-time-order correlators (OTOCs), which reveal signatures of chaos beyond spectral statistics. Focusing on the open anisotropic Dicke model, we identify two distinct regimes: transient chaos, marked by rapid early-time growth of VNE and OTOCs followed by low saturation values, and steady-state chaos, characterized by high long-time values. We introduce a random matrix toy model and show that Ginibre spectral statistics signals short-time chaos rather than steady-state chaos. Our results establish VNE dynamics and OTOCs as reliable diagnostics of dissipative quantum chaos across different timescales.

Using pulsar accelerations, we identify and constrain the properties of a dark matter subhalo in the Galaxy for the first time from analyzing the acceleration field of binary and solitary pulsars. The subhalo is characterized by analyzing a local deviation from a smooth potential. Our MCMC calculations show that this subhalo has a mass of ${2.45}_{-0.96}^{+1.07}\times {10}^7{M}_{\odot }$ and is located at Galactocentric coordinates $X={7.43}_{-0.12}^{+0.2}\mathrm{kpc}$, $Y={0.38}_{-0.16}^{+0.11}\mathrm{kpc}$, $Z={0.21}_{-0.11}^{+0.06}\mathrm{kpc}$, using flat, uninformative priors, where we have modeled the sub halo as a compact object. The Bayes factors for the models are in the range of $\sim 20–40$, which indicates tentative evidence (though not yet decisive) for the subhalo. Modeling the subhalo with a NFW profile gives a subhalo mass of ${6.19}_{-2.03}^{+1.92}\times {10}^7{M}_{\odot }$, located at $X=7.47_{-0.14}^{+0.21}$, $Y=0.38_{-0.16}^{+0.11}$, $Z=0.21_{-0.11}^{+0.06}$; the mass within the scale radius (0.1 kpc) for the NFW profile is ${0.48}_{-0.16}^{0.15}\times {10}^7{M}_{\odot }$. We examine Gaia data and the atomic and molecular hydrogen data of our Galaxy and show that the measured deviation from a smooth potential cannot arise from the gas or the stars in our Galaxy. Additionally, by analyzing the full sample of binary pulsars with available acceleration measurements that span 3.4 kpc in Galactocentric radius from the Sun and 3.6 kpc in vertical height, we find that massive (with mass $>{10}^8{M}_{\odot }$) subhalos are disfavored for the Milky Way within several kiloparsec of the Sun. While smaller sub-halos may be present, they are beyond the reach of current direct acceleration measurements. The presence of a $\sim {10}^7{M}_{\odot }$ subhalo within a few kpc of the Sun is potentially consistent with the expected number counts of sub-halos in the prevailing $\mathrm{\Lambda }\mathrm{CDM}$ paradigm, for a substantial subhalo mass fraction. As the number and precision of direct acceleration measurements continues to grow, we will obtain tighter constraints on dark matter sub-structure in our Galaxy. This Letter now provides a proof of principle for probing nearby, low-mass subhalos, and has implications across many fields of astrophysics—from understanding the nature of dark matter to galaxy formation.

The thermal confinement phase transition in $\mathrm{SU}(N)$ Yang-Mills theory is first order for $N\ge 3$, with bounce action scaling as $N^2$. Remarkably, lattice data for the action include a small coefficient whose presence likely strongly alters the phase transition dynamics. We give evidence, utilizing insights from softly broken supersymmetric Yang-Mills models, that the small coefficient originates from a deconfined phase instability just below the critical temperature. We predict the maximum achievable supercooling in $\mathrm{SU}(N)$ theories to be a few percent, which can be tested on the lattice. We briefly discuss the potentially significant suppression of the associated cosmological gravitational wave signals.

Symmetry analysis provides crucial insights into the magnetoelectric coupling effect in type-II multiferroics. In this Letter, we comprehensively investigate couplings between electric polarization and inhomogeneous magnetization across all 32 nonmagnetic point groups using a phenomenological Landau theory. Our theory successfully explains the ferroelectric polarizations in all known type-II multiferroics characterized by incommensurate magnetic orders. In addition, we predict 12 promising type-II multiferroic candidates with the highest magnetic transition temperature of 84 K through systematic screening of MAGNDATA database. Furthermore, we find that the collinear spin-sinusoidal texture emerges as a previously unrecognized source of ferroelectric polarization. We also demonstrate that topological ferroelectric vortex states can be induced by ferromagnetic vortex configurations in uniaxial point groups, opening a route to realizing coexisting multiple-vortex states in multiferroics.

Reservoir computing (RC) is a machine learning paradigm that harnesses dynamical systems as computational resources. In its quantum extension—quantum reservoir computing (QRC)—these principles are applied to quantum systems, whose rich dynamics broadens the landscape of information processing. In classical RC, optimal performance is typically achieved at the “edge of chaos,” the boundary between order and chaos. Here, we identify its quantum many-body counterpart using the QRC implemented on the celebrated Sachdev-Ye-Kitaev model. Our analysis reveals substantial performance enhancements near two distinct characteristic “edges”: a temporal boundary defined by the Thouless time, beyond which system dynamics is described by random matrix theory, and a parametric boundary governing the transition from integrable to chaotic regimes. These findings establish the “edge of many-body quantum chaos” as a design guideline for QRC.

A black hole is expected to end its lifetime in a cataclysmic runaway burst of Hawking radiation, emitting all standard model particles with ultrahigh energies. Thus, the explosion of a nearby primordial black hole (PBH) has been proposed as a possible explanation for the $\sim 220\mathrm{PeV}$ neutrino-like event recently reported by the KM3NeT Collaboration. If the event originated from a PBH, the source would need to lie at $(1–7)\times {10}^{-5}\mathrm{pc}$—depending on the assumed effective area—thus within the Solar System. At such proximity, the resulting flux of gamma rays and cosmic rays would be detectable at Earth. By incorporating the time-dependent field of view of gamma-ray observatories, we show that LHAASO should have recorded $\mathcal{O}({10}^8)$ events between fourteen and seven hours prior to the KM3NeT detection. IceCube and KM3NeT itself should likewise have detected of order a few hundred events in the range $1\mathrm{TeV}\lesssim E_{\nu }\lesssim 1\mathrm{PeV}$ during the 24 h preceding the burst. The absence of any such multimessenger signal, particularly in gamma-ray data, strongly disfavors the interpretation of the KM3-230213A event as arising from evaporation in a minimal four-dimensional Schwarzschild scenario.

We propose a novel, feedback-free method to cancel the effects of dephasing in the dynamics of open quantum systems. The protocol makes use of the coupling with an auxiliary system when they are both subjected to the same noisy dynamics in such a way that their interaction leads to cancellation of the noise on the system itself. This requires tuning the strength of the coupling between the main and auxiliary systems as well as the ability to prepare the auxiliary system in a Fock state, which solely depends on the coupling strength. We investigate the protocol’s efficiency to protect NOON states against dephasing in setups such as tweezer arrays of cold atoms. We show that the protocol’s efficiency is robust against fluctuations of the optimal parameters and, remarkably, that it is independent of the temporal features of the noise. Therefore, it could be applied to cancel both Markovian and non-Markovian dephasing noise, reaching regimes where error-correction protocols become inefficient.