Random quantum states have various applications in quantum information science. We discover a new ensemble of quantum states that serve as an ε-approximate state t-design while possessing extremely low entanglement, magic, and coherence. These resources can reach their theoretical lower bounds, Ω(log(t/ε)), which are also proven in this Letter. This implies that, for fixed t and ε, entanglement, magic, and coherence do not scale with the system size, i.e., O(1) with respect to the total number of qubits n. Moreover, we explicitly construct an ancilla-free shallow quantum circuit for generating such states by transforming k-qubit approximate state designs into n-qubit ones without increasing the support size. The depth of such a quantum circuit, O(t[logt]^{3}log n log[1/ε]), is the most efficient among existing algorithms without ancilla qubits. A class of quantum circuits proposed in our Letter offers reduced cost for classical simulation of random quantum states, leading to potential applications in quantum information processing. As a concrete example, we propose classical shadow tomography using an estimator with superpositions between only two states, from which almost all quantum states can be efficiently certified by requiring only O(1) measurements and classical postprocessing time.
Computing excitation spectra of quantum many-body systems is a promising avenue to demonstrate the practical utility of current noisy quantum devices, especially as we move toward the "megaquop" regime. For this task, here we introduce a tangent space excitation ansatz for quantum circuits, motivated by the quasiparticle picture of many-body systems and the structural similarity between quantum circuits and tensor networks. Increasing circuit depth by one layer to construct tangent space around the variational optimum of a parametrized quantum circuit, we show that massive low-energy single-particle states can be captured. Our ansatz relies on a distinct mechanism from that of the excitation ansatz in a matrix product state and projected entangled-pair state, and avoids intrinsic limitations of the latter. Comparing our approach with existing quantum excited-state algorithms, we find that with similar computational cost, both the number of excited states and accuracy are significantly improved. We demonstrate our ansatz in both one and two dimensions, and further show that this approach, implementable using the Hadamard test, is scalable and suitable for current quantum processors.
Controlling the quantum coherence of excitons in bulk semiconductors is crucial for developing scalable quantum photonic platforms. Here, we demonstrate active control of excitonic quantum beats in the 1S orthoexciton in cuprous oxide (Cu2O) via strain engineering. By applying uniaxial bending stress, we induce and precisely tune the fine structure splitting of the 1S orthoexciton. The split states display orthogonal linear polarizations, enabling selective preparation of coherent superpositions. The presence of a quantum beating signal confirms coherent coupling. Our results demonstrate that the beat frequency can be continuously tuned by changing the applied stress, and the beat amplitude can be switched on and off by rotating the detection polarization. These strain-controlled quantum interference effects not only shed light on the fundamental excitonic dynamics but also open avenues for exploiting Cu2O's unique properties in quantum optics and information processing.
The discrepancy between quantum distinguishability in Hilbert space and classical distinguishability in probability space is expressed by the gap between the quantum and classical Fisher information matrices (QFIM and CFIM, respectively). This intrinsic quantum obstruction is generally not saturable and plays a central role in both fundamental insights and practical applications in modern quantum physics. Here, we develop a geometrical framework for this gap by introducing the notion of the semiclassical geometric tensor (SCGT). We relate this quantity to the quantum geometric tensor (QGT), whose real part equals the QFIM. We prove the matrix inequality between QGT and SCGT, which sharpens the standard inequality between QFIM and CFIM and provides novel multiparameter information bounds: the real part of the SCGT reproduces the CFIM plus an additional nonnegative contribution capturing quantum obstruction. This further motivates a natural extension of the Berry phase to the semiclassical setting.
We prove that the time required for sustained information scrambling in any Hamiltonian quantum system is universally at least logarithmic in the entanglement entropy of scrambled states. This addresses two foundational problems in nonequilibrium quantum dynamics. (1) It sets the earliest possible time for the applicability of equilibrium statistical mechanics in a quantum system coupled to a bath at a finite temperature. (2) It proves a version of the fast scrambling conjecture, originally motivated in models associated with black holes, as a fundamental property of quantum mechanics itself. Our result builds on a refinement of the energy-time uncertainty principle in terms of the infinite temperature spectral form factor in quantum chaos. We generalize this formulation to arbitrary initial states of the bath, including finite temperature states, by mapping Hamiltonian dynamics with any initial state to nonunitary dynamics at infinite temperature. A regularized spectral form factor emerges naturally from this procedure, whose decay is universally constrained by analyticity in complex time. This establishes an exact speed limit on information scrambling by the most general quantum mechanical Hamiltonian without any restrictions on locality or the nature of interactions.
Holographic complexity, as the bulk dual of quantum complexity, encodes the geometric structure of black hole interiors. Motivated by the complexity = anything proposal, we introduce the spectral representation for generating functions associated with codimension-one and codimension-zero holographic complexity measures. These generating functions exhibit a universal slope-ramp-plateau structure analogous to the spectral form factor in chaotic quantum systems. In such systems, quantum complexity evolves universally, displaying long-time linear growth followed by saturation at late times. By employing the generating function formalism, we show that this universal behavior has two origins: a particular pole structure of the matrix elements of the generating functions in the energy eigenbasis and random matrix universality in spectral statistics. Using the residue theorem, we prove that the existence of this pole structure is a necessary and sufficient condition for the linear growth of holographic complexity measures. Furthermore, we show that the late-time saturation plateau arises directly from the spectral level repulsion, a hallmark of quantum chaos.
We provide a new perspective on the cosmological constant by exploring the background-independent Wheeler-DeWitt quantization of general relativity. The Chern-Simons-Kodama state of quantum gravity, a generalization of the Hartle-Hawking and Vilenkin states, has a striking structural similarity to the topological field theory of the quantum Hall effect. As a result, we study the gravitational topological θ sectors in analogy to Yang-Mills theory. We find that the cosmological constant Λ is intimately linked to the θ parameter by θ=12π^{2}/(Λℓ_{Pl}^{2}) mod 2π due to the fact that Chern-Simons-Kodama state must live in a particular θ sector. This result is shown in the canonical, nonperturbative formalism. Furthermore, we explain how the physics of the Hamiltonian constraint is analogous to the quantum Hall effect, with the cosmological constant playing the role of a quantum gravitational Hall resistivity. These relations suggest that Λ is topologically protected against perturbative graviton loop corrections, analogous to the robustness of quantized Hall conductance against disorder in a metal.
Dynamical control of quantum matter is a challenging, yet promising direction for probing strongly correlated states. Motivated by recent experiments in twisted MoTe_{2} that demonstrated optical control of magnetization, we propose a protocol for probing magnetization dynamics in flat-band ferromagnets. We investigate the nucleation and dynamical growth of magnetic bubbles prepared on top of a false vaccum in both itinerant ferromagnets and spin-polarized Chern insulators. For ferromagnetic metals, we emphasize the crucial role of a nontrivial quantum geometry in the magnetization dynamics, which in turn also provides a probe for the quantum metric. Furthermore, for quantum Hall ferromagnets, we show how properties of chiral edge modes localized at domain-wall boundaries can be dynamically accessed. Our Letter demonstrates the potential for nonequilibrium protocols to control and probe strongly correlated phases, with particular relevance for twisted MoTe_{2} and graphene-based flat-band ferromagnets.
Atom arrays have emerged as a powerful platform for quantum light-matter interfaces, yet single-species arrays are constrained by in-plane symmetry, restricting polarization control. Here, we investigate the cooperative optical response of dual-species subwavelength atom arrays, in which the intrinsic polarizability difference breaks in-plane symmetry. By engineering the lattice constants and detunings, the arrays exhibit polarization-dependent subradiant modes, enabling complete reflection of a specific polarization component. Leveraging this mechanism, we assemble array units as functional pixels and demonstrate a scalable polarization-selective quantum light modulator. Our work establishes a dynamically reconfigurable atomic-photonic platform for versatile subwavelength quantum optical elements.
We propose a model based on density functional theory (DFT) and quantum electrodynamics (QED) to study the dynamical characteristics of graphene quantum dots (GQDs). We assume the GQD edges are saturated with hydrogen atoms, effectively making it a polycyclic aromatic hydrocarbon (PAH) such as coronene. By combining the GQD spectrum calculated from a time-dependent DFT (TDDFT) with the dynamical behavior of a QD model derived from QED, we calculate the main optical characteristics of the GQD, such as its transition frequencies, the dipole moment associated with each of those transitions, life-time, and the population dynamics of the molecular levels. Owing to the close match between the simulated spectrum and experimental results, our DFT-QED model represents a significant contribution to research on quantum treatments of light-matter interactions in realistic 2D nanomaterials.
The advancement of inverted quantum-dot light-emitting diodes (QLEDs) is fundamentally hindered by inefficient charge injection and severe interfacial energy barriers. Here, we propose a bilateral charge-generation layer (CGL) architecture integrating two complementary heterojunctions: PEDOT:PSS/ZnO and N,N-bis(4-methylphenyl) benzenamine (TAPC)/1,4,5,8,9,11-hexaazatriphenylenehexacarbonitrile (HAT-CN). This architecture decouples the carrier supply from electrodes, enabling balanced carrier injection into the quantum-dot emissive layer. The resulting inverted QLEDs achieve a record-high external quantum efficiency (EQE) of 30.8% for red emission and a high EQE of 20.1% for green emission, corresponding to current efficiencies of 40.8 and 88.1 cd A-1, respectively. These bilateral CGL devices also exhibit extended stability, with extrapolated T50 lifetimes of ∼36,494 h (red) and ∼39,962 h (green) at 100 cd m-2. Both the efficiencies and lifetimes significantly outperform their unilateral counterparts. This work establishes a practical design pathway for efficient and stable inverted QLEDs, providing useful insights for advancing emerging optoelectronic technologies.
We derive detailed and intergral fluctuation relations as well as a thermodynamic uncertainty relation constraining the exchange statistics of an arbitrary number of noncommuting conserved quantities among two quantum systems in transport setups arbitrary far from equilibrium. These universal relations, valid without the need of any efficacy parameter, extend the well-known heat exchange fluctuation theorems for energy and particle transport to the case of non-Abelian quantum transport, where the noncommutativity of the charges allows going beyond standard thermodynamic behavior. In particular, we show that this can lead to enhanced precision in the current fluctuations, and it allows for the inversion of all currents against their affinity biases.
Achieving strong light-matter interaction to manipulate emission requires integrating colloidal perovskite quantum dots (PQDs) with plasmonic nanocavities, yet this integration is challenged by their vulnerability to polar solvents. We successfully synthesized highly emissive, solvent-resistant CsPbI3 PQDs and integrated them into nanoparticle-on-mirror structures. This integration enabled a 435-fold reduction in emission lifetime and a 250-fold increase in total emission intensity. Key results include a very short radiative lifetime below 12 picoseconds and a record-high single-photon emission rate exceeding 2.3 × 109 counts per second at room temperature. Notably, we also observed nonblinking single-photon emission with high purity arising from nanocavity-enhanced radiative electron-hole recombination. Finite-difference time-domain simulations confirmed ultrasmall mode volumes of ~3 × 10-5 (λ/n)3, effectively enhancing spontaneous emission via the Purcell effect. These ultrabright and nonblinking properties highlight the strong potential of this platform for future quantum technology applications.
Quantum chemical mapping of weak interaction networks in N2O4/HNO3/H2O and HNO3/N2O4 propellant systems is reported. Electrostatic potential analysis identifies HNO3 as the dominant hydrogen bond donor (+64.28 kcal/mol), forming the strongest complex with H2O (-9.45 kcal/mol). In the ternary HNO3···N2O4···H2O cluster, water acts as a polarization catalyst, inducing a cooperative stabilization of 1.99 kcal/mol by enhancing the HNO3 donor ability. Most significantly, in water-depleted 2HNO3···N2O4 clusters, a specific weak interaction topology prefigures a concerted double proton transfer pathway (ΔE‡ = +32.1 kcal/mol), forming [HNO2···NO2+]···NO3- ion pairs. This finding provides a new theoretical hypothesis for the source of ions beyond the dissociation of HNO3 in future studies of corrosion origin. Solvation models further confirm the persistence of these weak interaction networks and the feasibility of the proposed proton transfer pathway in the liquid N2O4 environment.
Physical Gottesman-Kitaev-Preskill (GKP) states are inherently noisy as ideal ones would require infinite energy. While this is typically considered as a deficiency to be actively corrected, this Letter demonstrates that imperfect GKP stabilizer states can be leveraged in order to apply non-Clifford gates using only linear optical elements. In particular, Gaussian operations on normalizable GKP states, combined with homodyne measurements, permit two key primitives: clean projection onto Pauli eigenstates in the normalizable GKP code space, thereby implementing Clifford gates with high fidelity; and probabilistic projection of unmeasured modes onto non-Pauli eigenstates. These results demonstrate that normalizable GKP stabilizer states combined with Gaussian operations provide a practical framework for computational universality within the measurement-based model of quantum computation in a realistic continuous-variable setting.
The article is devoted to topical issues of genetic biomechanics, which studies structural connections between molecular-genetic informatics and inherited physiological complexes. It is known that amino acid sequences of proteins are genetically inherited using code messages in DNA and RNA molecules based on the alphabet of 4 nucleotides. But, as Nobel laureate geneticist T. Steitz emphasizes, all knowledge about these biomolecules encoded in the genome in this biochemical alphabet will not tell us about the inheritance of biomechanical algorithms and functions by genetic automata. Thus, in modern science of biological inheritance, there is no knowledge about a bioinformation system capable of ensuring the inheritance of cooperative phenomena of algorithmic behavior of body parts. These inherited logical forms of algorithmic behavior in biosystems require the search for bioinformation alphabets that could form the basis for the operation of genetic automata and the algorithmic inheritance of biological structures. The article describes the genetic algebraic-operator alphabets, identified as a result of such a search, based on unitary Hadamard matrices, as well as cyclic power groups based on them, which make it possible to model inherited cyclic and biorhythmic structures in connection with the formalisms of quantum logic. The evolutionary paradigm of algebraic-alphabetic Darwinism has been formulated. Related issues of inherited brain mechanisms, artificial intelligence, and the functioning of operators in human-machine systems are discussed.
We develop a theoretical framework for probing superconductivity with momentum resolution using the quantum twisting microscope (QTM), a planar tunneling device where a graphene tip is rotated relative to a two-dimensional sample. Because of in-plane momentum conservation, the QTM directly measures the superconducting spectral function along well-defined trajectories in momentum space. The relative intensities of electron and hole excitations encode the Bogoliubov coherence factors, revealing the momentum dependence of the pairing magnitude. Three C_{3z}-related tunneling channels enable direct detection of rotational symmetry breaking, as well as nodal points in the superconducting order parameter. We apply our framework to superconductivity within the Bistritzer-MacDonald model of noninteracting electrons and the topological heavy-fermion model, which accounts for electron-electron interactions. Together, these capabilities establish the QTM as a direct probe of the pairing symmetry and microscopic origin of superconductivity in two-dimensional materials.
We identify, for a general physically realizable Mueller transformation, the only intrinsic geometric-phase structure that can be assigned to it in an invariant manner: the retarding part of the characteristic pure component selected by the characteristic decomposition, which defines a canonical holonomic content. A Mueller matrix does not, in general, determine a unique observed interferometric (Pancharatnam) geometric phase, since the latter depends on the specific physical realization of the transformation and on the interferometric readout. The remaining characteristic layers may modify the measured complex visibility, and even its observed argument through convex averaging, but they do not define a unique geometric holonomy of their own. We further establish the quantum analog for open two-level dynamics within the Choi representation.
The development of stable, environmentally benign, and high-performance perovskite solar cells (PSCs) has increasingly focused on innovative inorganic absorber materials. In this study, we conduct a detailed evaluation of the optoelectronic and mechanical properties of Ca3AsBr3, a promising non-toxic halide perovskite, using density functional theory (DFT) alongside SCAPS-1D simulations. The DFT results indicate that Ca3AsBr3 possesses a direct bandgap of 1.66 eV, along with good mechanical stability and strong optical absorption, making it well-suited for photovoltaic applications. To further investigate device performance, four electron transport layers (ETLs)-WS2, SnS2, CdS, and TiO2 were incorporated into HTL-free FTO/ETL/Ca3AsBr3/Au architecture, allowing analysis of energy band alignment, defect tolerance, and overall efficiency. Among these configurations, the WS₂-based device demonstrated superior performance, achieving a power conversion efficiency (PCE) of 20.50%, with an open-circuit voltage (Voc) of 1.165 V, a short-circuit current density (Jsc) of 20.55 mA/cm², and a fill factor (FF) of 85.64%. Further simulation results highlight that an optimal absorber thickness of 1200 nm, along with reduced bulk and interface defect densities (≤ 10¹⁵ cm⁻³ and ≤ 10¹³ cm⁻²), plays a crucial role in minimizing non-radiative recombination losses and improving charge carrier collection. Overall, this work identifies Ca3AsBr3 as a viable eco-friendly absorber material and emphasizes the importance of ETL optimization in achieving efficient, stable, and scalable PSC devices.
We obtain the spectra of codimension-2 horizon "edge" degrees of freedom for gravity and higher-spin gauge fields in de Sitter space and in the static Nariai spacetime, advancing previous Lorentzian and Euclidean analyses of one-loop thermodynamics. The edge spectra exhibit universal shift symmetries, revealing a novel symmetry-breaking structure in one-loop partition functions with a positive cosmological constant. For the graviton, these modes admit a geometric interpretation as fluctuations of the cosmic horizon, which also persists in the Nariai case.