October 26, 2026

Two-Layer Verification for Fault-Tolerant Magic-State Preparation in High-Rate Quantum CodesTier 3

Encoded magic states are essential for universal fault-tolerant quantum computation, but their resource-efficient preparation in high-rate quantum codes remains challenging. To address this limitation, we propose two-layer verification, which combines local verification of independently prepared subblocks with logical verification after their embedding into a target code. Th...

Photon-Number Discrimination from Increasing Time-of-Arrival Separation in Wide Superconducting Microstrip Single-Photon DetectorsTier 3

Measurements of photon-number-dependent time-of-arrival (TOA) distributions in wide NbN superconducting microstrip single-photon detectors (SMSPDs) are presented. Two \SI{10}{\um}-long devices with widths of \SI{3.2}{\um} and \SI{6.4}{\um} are characterized under pulsed \SI{515}{nm} excitation. The TOA histograms are described by sums of exponentially modified Gaussian (EMG)...

Trident: Efficient Load Verification for Yoked Surface Codes using a Three-Level Memory HierarchyTier 3

Fault-Tolerant Quantum Computers (FTQCs) commonly use the surface code to encode program qubits as error-corrected logical qubits. Unfortunately, the surface code has a poor encoding rate, so recent work has proposed Yoked Surface Codes (YSCs), which concatenate the surface code with a high-rate quantum code. The surface code qubits in YSCs are protected by the checks, or yo...

Low-frustration block encodings by patch routingTier 3

Block-encoding has emerged as a core primitive in many quantum algorithms, including quantum simulation. In this work, we design efficient and extensible methods for generating low-frustration block encodings of frustrated lattice Hamiltonians built from repeated local interaction patches through a technique we call "patch routing". We construct block encodings for a full Ha...

Hardware-Friendly Estimation of LCU-Based Expectation Values via Quantum-to-Classical Workload ShiftingTier 3

Estimating the expectation value of an observable O for a quantum state evolved under a general, possibly non-unitary, operator A is a fundamental task in quantum simulation, chemistry, and variational algorithms. Existing linear-combination-of-unitaries (LCU) approaches implement A on hardware, requiring ancilla qubits, controlled unitaries and, in randomized variants...

Modular optical fault-tolerant quantum computation via an interface between verified resources and online logical operationsTier 3

We introduce a factory--processor interface architecture for modular optical fault-tolerant quantum computation that separates code-dependent encoded-resource preparation from reusable online logical processing on a common Gaussian optical processor. Beyond encoded resources, the interface specifies logical outputs, code-to-mode mapping, measurement roles, frame updates, ver...

Trace-distance characterization of recurrent pairwise synchronization in cavity-coupled superconducting qubitsTier 3

We theoretically investigate recurrent pairwise synchronization in three super?conducting qubits coupled to a common single-mode microwave cavity. The qubits interact indirectly through the cavity field and are driven by a coher?ent microwave field. We obtain the coherent dynamics in the dressed-state basis and quantify pairwise synchronization by the trace distance between...

Quantum Secret Sharing from CSS qLDPC Codes: Computable Access Structures, Accessible Logical Dimension, and Topology-Aware Network CostTier 3

Quantum secret sharing (QSS) schemes can be constructed from quantum error-correcting codes, but characterizing their access structures and implementation costs becomes challenging for finite-length, high-rate quantum low-density parity-check (qLDPC) codes. We develop an exact computational framework for QSS induced by CSS qLDPC codes. The framework characterizes authorized,...

Quantum Machine Learning in Medical Imaging: A Primer for RadiologistsTier 3

Deep learning has transformed radiology, but the computational cost of training and deploying modern models is outpacing what classical hardware can support. Quantum computing has been proposed as one response to this bottleneck: an n-qubit system can represent 2^n states simultaneously, although practical speedups require efficient algorithms, data encoding, and measureme...

Near-field maps of topological edge states of molecular aggregatesTier 3

Self-assembled two-dimensional molecular aggregates provide a versatile platform for engineering excitonic states, including topologically nontrivial edge states. However, these edge-states are difficult to probe optically: they have weak far-field transition strengths, and far-field spectra do not reveal whether an excitation is localized at the edge. For an aggregate consi...

Ideal interaction dynamics of defects and background fields in condensed matterTier 3

While defect dynamics in condensed matter systems is widely studied and several methods are available to track the defect position over time, the formulation of dynamical models for the coupled evolution of both defect and background field quantities seems to be more challenging. Yet, the overall behavior of a system containing moving defects is strongly influenced by this d...

Distributed Quantum-Centric Supercomputing with Multi-Layered Generative Learning for Intermolecular InteractionsTier 3

Quantum-centric supercomputing (QCSC) approaches, such as sample-based quantum diagonalization (SQD), combine quantum processors with high-performance computers (HPC), offering a promising route toward solving challenging electronic structure problems. However, implementation of QCSC approaches to large active space calculations is constrained by the associated number of qub...

Exploiting the Weyl-Chamber Structure for Hardware-Aware Quantum Circuit CompressionTier 3

Quantum circuit compression based on tensor networks enables long-time simulation of quantum many-body dynamics on near-term hardware. While Riemannian optimization has been successfully employed for this purpose, it typically optimizes over the manifold of generic two-qubit unitaries. Consequently, the resulting gates must still be synthesized into the hardware's native gat...

A note on the monotonicity of observational ergotropic advantageTier 3

Very recently, Mahanti et al. (arXiv:2609.18735) introduced the observational ergotropic advantage, which gives the maximum value of extra work that a measurement can obtain with respect to all incoherent measurements. However, the above quantity does not show monotonic behaviour under the resource theory of measurement coherence. So, the search for a resource theory in whic...

Classical Pre-Training of Large Shallow Parametrized Quantum Circuits through Pauli Propagation and deployment on Quantum HardwareTier 3

Scaling parametrized quantum circuits to a larger number of qubits is a central challenge in Quantum Machine Learning: gradient estimation via the parameter-shift rule quickly becomes prohibitively expensive, while gradient-free optimizers offer limited convergence guarantees. We apply the Pauli propagation framework to a broad class of Quantum Machine Learning problems in w...

Quantum Evolution Networks Learn Long-Time Coherent Dynamics in Driven Spin RegistersTier 3

Predicting and controlling driven quantum systems requires access to dynamics across physical parameters, initial states, and evolution times. A reusable neural model must capture this dependence while preserving unitary structure and maintaining accuracy over long-time coherent evolution. Here we introduce Quantum Evolution Networks (QENs), which map physical parameters and...

Maximal Orbital Entanglement from Non-Interacting FermionsTier 3

Orbital rotations are used in quantum many-body physics and chemistry to reduce the complexity of quantum states by compressing their correlation into a small set of relevant orbitals. In striking contrast, quantum information processing strives for the opposite: orbitals that maximize entanglement as a resource. Motivated by this, we prove that Slater determinants of N fe...

Certain Quantum States Already Require Quantum Time EvolutionTier 3

Model-independent tests of quantum theory, such as Bell inequality violations, focus on static properties of the theory and do not rely on its dynamical aspects. Hence, this core part of quantum theory remains largely untested in a model-independent way. We show that the structure of quantum time evolution can be examined by testing the consistency between the state space an...

Generating entanglement in quantum matter with pathway-entangled photons via resonant inelastic X-ray scatteringTier 3

Resonant inelastic X-ray scattering (RIXS) is conventionally used to probe elementary excitations and correlations in quantum materials. Here, we propose an interferometric RIXS protocol that instead creates entanglement between spatially separated regions of a solid-state material. An incident X-ray photon is coherently split by a beam splitter into two arms illuminating op...

One-sided-DIQKD using any pure bipartite entangled state secure against all attacksTier 3

Quantum Key Distribution (QKD) allows spatially separated parties to establish a secret key among themselves based on quantum principles. While QKD systems are being deployed worldwide, their reliance on trusted measurements makes them vulnerable. Moreover, existing protocols have largely focussed on the qubit cases, and rely on the maximally entangled state, a costly resour...

Nonclassicality from Incomplete Fock-State StatisticsTier 3

Nonclassicality in bosonic systems can be certified directly from occupation probabilities without full state reconstruction. To complete a library of such criteria we introduce a numerical framework that constructs optimal linear nonclassicality witnesses from arbitrary subsets of measured occupation probabilities by solving a semi-infinite linear program. The method contai...

Minimal unitary representations of time-invariant causal quantum channelsTier 3

In this work, we study quantum channels that respect causality in single-input-single-output linear time-invariant systems. We show that positive semidefinite kernels satisfying certain analyticity constraints, which we call Schur-class kernels, provide a suitable description of such channels through multiplicative maps (Schur multipliers). Using the Moore-Aronszajn Theorem,...

Bounding single-copy information causality violationsTier 3

Information causality is a physical principle that constrains bipartite post-quantum nonlocal correlations from information-theoretic assumptions. A direct characterization of the correlations satisfying it, however, remains difficult because the defining entropic condition must hold for all admissible protocols in the corresponding task. Here, we formulate the single-copy i...

Entanglement Asymmetry and Asymmetry Contour under Boundary Symmetry BreakingTier 3

We investigate how symmetry-breaking boundary magnetic fields affect magnetization and Rényi-2 entanglement asymmetry (EA) in the transverse-field Ising model. For the ground state, magnetization exhibits qualitatively distinct behaviors in the ordered and disordered phases. EA also exhibits phase-dependent behavior, which is well captured by the lower and upper bounds deriv...

Discrete WKB approach to density profiles in inhomogeneous two-band free-fermion chainsTier 3

We extend the discrete WKB method to one-dimensional bipartite tight-binding chains of free fermions with slowly varying hopping amplitudes and on-site potentials. We focus on the inhomogeneous Rice-Mele model, suggesting possible experimental realizations thereof in optical superlattices. We derive explicit semiclassical expressions for the single-particle wave functions an...

Elementary proofs of quantum lower bounds for element distinctness and k-sumTier 3

We give elementary proofs of the Ω(n^(2/3)) quantum query lower bound for element distinctness and the Ω(n^(k/(k+1))) lower bound for the k-sum problem, for fixed k and sufficiently large groups. The proofs use only basic properties of quantum states and linear algebra, analyzing the differences of algorithm states on different inputs.

An Invitation to Algebraic Methods in Quantum TheoryTier 3

In this paper, we present various well-studied examples of quantum systems, and discuss how they might be analysed algebraically. We analyse the harmonic oscillator, hydrogenic atom, optical components, and particle spin using multiple algebraic methods, and highlight the central importance of algebraic relationships between operators in determining the physical character of...

From Link Availability to Deadline-Constrained Key Service: A Feasibility Framework for Mobile Free-Space Quantum Key DistributionTier 3

Mobile free-space quantum key distribution (QKD) links can provide secret bits intermittently, whereas applications may need cryptographic key material at specified times. Optical feasibility, positive finite-key output, and deadline-compliant key service are consequently different claims. This technical note formalizes their separation through a time-indexed, security-quali...

QuantumBilliards.jl: An extensible, user friendly, high-performance Julia library for the large scale computation of spectra and eigenstates of quantum billiards and related problemsTier 3

We present QuantumBilliards.jl, an open-source Julia library providing a suite of numerical solvers for the two-dimensional interior Helmholtz eigenproblem with Dirichlet boundary conditions, a paradigmatic model in quantum chaos. The library implements conventional wavenumber-sweep techniques together with several accelerated eigensolvers: the Vergini--Saraceno scaling meth...

The Compendium of Super-Quadratic Computational Quantum AdvantagesTier 3

This compendium presents a structured collection of computational problems with credible prospects for realizing meaningful quantum advantage, focused on describing problem characteristics rather than specific algorithms. It is intended for non-quantum researchers and practitioners with strong computational backgrounds, particularly domain experts, seeking to assess the rele...

Photon-Pair Advantage for Dissipative Parameter Estimation in Whispering-Gallery-Mode InterferometersTier 3

We study the estimation of detuning and intrinsic loss in a lossy whispering-gallery-mode (WGM) resonator located in a balanced Mach--Zehnder interferometer. We use indistinguishable photon pairs and coherent-state probes. We show that using indistinguishable photon pairs can provide higher Quantum Fisher Information (QFI) of dissipative parameters, such as intrinsic loss, a...

Quantum theory of laser noise in coherent-scattering levitated optomechanicsTier 3

State purity is a key resource for experimental tests of quantum mechanics with massive objects. Cavity cooling of a levitated nanoparticle via coherent scattering stands out as a strategy to prepare highly pure states of its roto-translational motion. In several cases, though, the performance of cooling by coherent scattering is limited by the classical fluctuations of the...

Finite Nonsignalling Resources Suffice to Simulate Entangled QubitsTier 3

A longstanding question in Bell nonlocality is whether finite-alphabet nonsignalling resources can reproduce the continuum of measurement correlations of partially entangled qubits. Here we resolve this problem by showing that every fixed pure two-qubit state admits an exact simulation of all local projective-measurement statistics using shared randomness and finitely many P...

Fundamental bound on Wigner negativity generation from environmental collisionsTier 3

Beyond quadratic potentials, classical evolution laws are typically thought to arise from quantum theory as an approximate description. Here we show that classical evolution laws can emerge exactly, provided the environment interacts with the system via collisions. We use this to derive an inequality that lower bounds the distribution of environmental momentum kicks by the a...

High Resolution Hyperspectral Quantum Infrared Imaging with Undetected PhotonsTier 3

Quantum sensing in the infrared regime often demands the use of expensive and cryogenically operated detectors. Nonlinear interferometry has paved the way for information transfer from the infrared to the near--infrared or visible regime in various quantum technologies. A particularly interesting application of these interferometers involves spectrally--resolved quantum imag...

Bose-Einstein condensate in a shell: nonlinear modes and symmetry breakingTier 3

The state of a quantum particle confined to a spherical surface is commonly described using spherical harmonics, which play a crucial role in solving many scientific problems featuring spherical symmetry. A mean-field description of a system of many interacting quantum particles confined to a spherical shell naturally leads to nonlinear generalizations of spherical harmonics...

Performing a Quantum Subroutine Using Cluster StatesTier 3

Quantum subroutines, like their classical counterparts, serve as essential components of larger algorithms. They can be realized using gate based architectures or measurement based quantum computation (MBQC), where computation proceeds through adaptive measurements on highly entangled cluster states. In this work, we implement a phase oracle as a reusable subroutine within t...

Traceable Quantum Secret SharingTier 3

Quantum secret sharing protects distributed quantum information against unauthorized reconstruction, yet existing schemes provide no intrinsic accountability when shares are leaked or forged. This missing capability is particularly relevant in realistic distributed settings, where compromised participants may either expose valid shares or maliciously interfere with reconstru...

Bogoliubov Dynamics and Zitterbewegung in Optical Dirac SystemsTier 3

We develop a bosonic Bogoliubov description of Zitterbewegung in time-dependent optical-Dirac systems. Within the optical-Dirac framework, the anomalous pair-creation and pair-annihilation terms of a bosonic Bogoliubov Hamiltonian correspond to couplings between the positive- and negative-frequency sectors, whose coherence underlies the Zitterbewegung response. When the cons...

Single-step SU(3) Hahn Echo in a Qutrit Atom InterferometerTier 3

The Hahn echo is a well-known dynamical decoupling method that refocuses the dephasing due to energy inhomogeneities of a spin-1/2 ensemble and is widely used to extend phase coherence in quantum computers and sensors. Extensions of such techniques beyond the spin-1/2 have been reported, but have mainly used SU(2) gates, limiting their scalability. Here, we generalize the Ha...

Quantum Cryptomania with Classical Communication without One-Way FunctionsTier 3

In classical cryptography, one-way functions are necessary for most of cryptography. In the quantum world, however, Kretschmer at {TQC'21} and subsequent works have demonstrated that quantum versions of various primitives in minicrypt, such as signatures and private-key encryption, do not require quantum-computable one-way functions (\textsf{qOWF}s). However, the question of...

Kinetic competition controls loss-induced exceptional points of Hubbard pairsTier 3

Two-body loss can bind two fermions in a Hubbard lattice, yet the binding threshold in the infinite lattice need not be an exceptional point (EP). At fixed total momentum K, the hops of the two particles interfere into a relative-motion hopping along each lattice direction, which sets the kinetic energy of the relative motion. On a hypercubic lattice, the threshol...

LYNX - A trapped-ion quantum information processorTier 3

We introduce LYNX, a quantum information processor based on trapped ^(40)Ca^+ ions. It utilizes up to 31 qubits with all-to-all connectivity. We characterize the system performance using rigorous benchmarks, such as randomized benchmarking (RB), GHZ state fidelity estimates, and quantum volume (QV) tests. The LYNX processor shows average 1-qubit gate errors of 8(5)time...

Optimizing Quantum Battery via Counterdiabatic drivingTier 3

We analyze the energy charging of a quantum battery within an open quantum framework, where the interaction between the battery element and an external power source is mediated by an ancilla system acting as a controllable switch. Specifically, we investigate the charging and discharging dynamics of a cavity-based quantum battery coupled to a driven qubit functioning as the...