July 9, 2026

Multi-stage Quantum Amplifier Readout Chain

Multi-stage cryogenic readout chains with a wide bandwidth and added noise within a few quanta of the quantum limit are frequently constructed using traveling-wave parametric amplifiers (TWPAs) as the first stage, and a semiconductor amplifier as the second stage. Unfortunately for highly-scaled superconducting detector arrays, or quantum information systems, and space-based...

Covariant Approximate Quantum Codes for Protected Analog Computation

Quantum error correction compatible with continuous symmetries is a fundamental problem in quantum information and a possible route to robust analog quantum simulation. Because the Eastin-Knill theorem forbids exact codes with continuous transversal symmetries, we construct explicit SU(d)-covariant approximate codes that exploit permutation symmetry to spread logical infor...

Variational Learning with Sparse Long-range Entangling Gates

The performance of variational quantum algorithms depends in general on the structure of the parametrized quantum circuit, but the most common ansätze are typically based on local couplings. Motivated by the extended connectivity available with neutral atoms and trapped ions, we examine when structured long-range connectivity provides a useful resource, focusing on sparse po...

Turing mechanisms in a multimode open quantum system

We investigate pattern formation in a finite chain of bosonic modes whose dynamics is governed by a Gorini-Kossakowski-Sudarshan-Lindblad (GKSL) master equation. The model combines local parametric driving and nonlinear damping with nonlocal dissipative couplings between modes that work on different discrete spatial scales. In the classical limit, these mechanisms generate a...

Spectral-width limit on non-Hermitian quantum metrology

Engineered loss, gain, and non-reciprocity can sharply amplify a sensor's response, and exceptional points and the skin effect are widely proposed as routes to more precise quantum sensors. Some predict an exponentially large quantum Fisher information, the quantity that sets the best achievable precision, yet whether this amplified response is genuine measurement informatio...

Circuit Depth Reduction of One-Ancilla Quantum Differential Equation Solver via Extrapolation

Solving linear differential equations is a fundamental task in scientific computing and an important primitive for quantum computing. A recent one-ancilla quantum differential equation solver provides a hardware-friendly and locality-preserving approach with provable performance guarantees, making it highly suitable for the early fault-tolerant and near-term regimes. Its sim...

Quantum simulation of real-world nonlinear dynamics via Koopman method

Nonlinear dynamics is ubiquitous in nature, ranging from chemical pattern formation to ocean circulation, yet its simulation on quantum computers is fundamentally limited by the unitary nature of quantum evolution. We propose the quantum Koopman method, a data-driven framework that embeds nonlinear dynamics into a learned linear representation and implements the resulting ev...

Quantum Computing : A New Frontier for Science and Society

This short report explores the (non exhaustive) current state of quantum technologies, their potential applications, and the challenges that must be addressed to harness their full potential. In particular we will focus on the quantum computer architecture and its ecosystem. Such architecture represents a complex, multi-layered system that integrates quantum and classical co...

QCNN with Rough Path Signature Kernels

Time series analysis plays a vital role across a wide range of scientific and engineering domains but poses substantial computational challenges. A major difficulty arises from the time reparameterization invariance of time series data, which complicates the extraction of meaningful temporal features. In this work, we address the problem of time series classification by expl...

Relativistic Quantum Thermometry in AdS Spacetime via Non-Markovian Temperature Sensing

Quantum thermometry based on single-qubit sensor configurations enables the precise estimation of the temperature of a cosmological Anti-de Sitter (AdS) spacetime. In this work, we characterize the achievable estimation accuracy using the Quantum Fisher Information (QFI) and the associated quantum signal-to-noise ratio. For the first time, we introduce an ancillary Unruh-DeW...

RubriQ: Rubric-Guided Group Relative Policy Optimization for Constraint-Aware Quantum Circuit Synthesis

Designing fault-tolerant quantum circuits that are both algorithmically correct and hardware compatible remains a major bottleneck in the transition to scalable quantum computing. We introduce RubriQ, a scalable framework that formulates circuit synthesis as a large language model (LLM) code-generation task, optimized via group relative policy optimization (GRPO). Unlike con...

An analytical solution of a quantum system with non-Markovian behavior: The Bixon-Jortner system in time domain

Non-Markovian behavior in quantum systems is often studied in the context of bipartite systems consisting of a system of interest and an environment -- tracing over the environment results in non-Markovian behavior for the subsystem of interest. One may get a Markovian limit in certain regimes, which is studied using the Lindblad master equation, and corrections to this beha...

Vectorizing Quantum Control: A RISC-V Vector Extension Architecture for Scalable Qubit Systems

The Quantum Control Processor (QCP) bridges the gap between compiler toolchains and control electronics, and is responsible for translating compiled quantum circuits into executable instructions that directly manipulate qubits and handle measurement feedback. However, existing designs rely primarily on customized instruction sets, limiting design reuse and requiring signific...

Horizon-Restricted Leading Soft QED as Open Quantum System

I formulate black-hole-horizon-induced decoherence of charged branch codes as the leading-soft QED restricted to an exterior algebra, formulated as an open quantum system. The fixed-history Feynman--Vernon identity calF[J,J]=1 remains exact. Decoherence enters through the unequal-history influence factor that survives exterior monitoring and belongs to the complementar...

Lecture notes on classical and quantum non-Markovianity

The study of non-Markovian quantum processes has attracted significant interest in recent decades, giving rise to several competing notions of quantum non-Markovianity. These notes serve as an introduction to the topic for graduate students familiar with quantum mechanics and probability theory. Owing to the vastness of the literature, we focus on two prominent characterizat...

SEALSQ and GlobalFoundries Form Alliance to Develop Post-Quantum Semiconductor Blocks and Cryogenic CMOS Infrastructure

Post-quantum hardware engineer SEALSQ Corp (Nasdaq: LAES) and foundry group GlobalFoundries (Nasdaq: GFS) have signed a strategic Memorandum of Understanding (MoU) to co-develop secure semiconductor platforms, post-quantum cryptography (PQC) IP, and cryogenic silicon control layers. The development track links GlobalFoundries' commercial Complementary Metal-Oxide-Semicond...

Multi-channel collective dissipation via the symmetric irreducible representation of SU(4)

We specialize Agarwal's multi-level collective spontaneous-emission formalism to the four-level case by formulating it in the fully symmetric \SU(4) representation of N identical atoms. In the irreducible representation (N,0,0), the occupation-number basis forms a tetrahedral weight lattice on which the six embedded su(2) transition subalgebras act as ladder...

Fidelity Analysis of Adiabatically Driven Donor Spins as Two-Qubit and Ququart Systems

Donor spin systems host a native Hilbert space whose dimension exceeds that of a qubit, meaning they can be used as qudits. Here we study a \ce{Si{:}P} donor spin system through leakage-aware randomized benchmarking (RB) of native ququart C_4 and encoded two-qubit C_2^(⊗2) Clifford groups. We implement adiabatic ramps to operate electron dipole...

RL-Guided Quantum-ALNS for Constrained VRP

This study develops a hybrid quantum-classical framework for constrained vehicle routing problems, focusing on the pickup-and-delivery problem with time windows. Instead of casting the full routing problem as a stand-alone quantum optimization task, we embed shallow quantum samplers inside the repair phase of an Adaptive Large Neighbourhood Search (ALNS) heuristic. A Deep Q-...

Quantum Boomerang Effect in Time-Crystalline Structures

The quantum boomerang effect (QBE) is a unique dynamical signature of Anderson localization, characterized by a launched wavepacket that initially drifts but ultimately returns to its initial position due to fundamental quantum interference. In this work, we theoretically establish and quantitatively characterize the QBE in a time-crystalline structure using a periodically d...

Dynamical structure factor with a pumping approach on a trapped-ion quantum computer

Dynamical structure factors (DSF) measured with neutron-scattering experiments provide key insights into the structure of materials. Their computation requires both the preparation of an equilibrium state and the implementation of Hamiltonian dynamics. We demonstrate the feasibility of computing DSF on the Quantinuum Reimei trapped-ion quantum computer, comparing the DSF of...

QAI Ventures Launches Inaugural Singapore Quantum Accelerator Cohort to Anchor APAC Expansion

Global venture capital firm QAI Ventures has officially launched the inaugural cohort of its Singapore Quantum Accelerator, marking the establishment of the state's first dedicated corporate quantum validation pipeline. Operated in direct cooperation with Enterprise Singapore and structured to align with Singapore’s National Quantum Strategy, the five-month regional progr...

Illinois Launches $3M X-Labs Fast Fund to Magnetize Federal Quantum Breakethroughs

Illinois Governor JB Pritzker and the Illinois Department of Commerce and Economic Opportunity (DCEO) have launched the X-Labs Fast Fund, a targeted $3 million state capital initiative designed to anchor incoming U.S. National Science Foundation (NSF) X-Labs engineering teams within the state. Operating as a programmatic multiplier for early-stage federal hardware develop...

European Consortium QUARTERNEXT Launches to Advance Certifiable Quantum-Key Distribution Systems

A multinational European deep-tech consortium named QUARTERNEXT has launched a four-year, cross-border initiative to mature and formally certify quantum-safe communication infrastructures. Coordinated by Spanish cybersecurity hardware developer Luxquanta, the project establishes a 48-month deployment pipeline that spans specialized entities across Spain, Austria, and the...

Error bounds for the truncated Baker--Campbell--Hausdorff and Zassenhaus formulas in unitary problems

The Baker--Campbell--Hausdorff (BCH) formula plays a critical role in many branches of mathematics and physics. It expresses the logarithm of the product of exponentials of non-commuting operators as an infinite series of nested commutators of the operators involved. The Zassenhaus formula is the dual of the BCH formula: the exponential of a sum of operators is written as an...

Faster quantum linear system solver beyond the condition number

The spectral condition number is a widely adopted measure of worst-case cost for quantum linear system solvers. Yet it can significantly overestimate the actual runtime for a typical problem instance. We present two quantum algorithms that produce the normalized solution |x⟩ of linear system Ax=| b ⟩ to accuracy ε with complexity independent of the conditio...

Acoustic-phonon-driven spin-lattice relaxation of the hBN boron vacancy in the sub-THz regime

The negatively charged boron vacancy center in hexagonal boron nitride is a premier candidate for quantum sensing, yet its performance is critically limited by longitudinal spin-lattice relaxation time (T_1). A microscopic understanding of spin relaxation in the high magnetic field regime remains elusive, as the relevant Zeeman transitions lie far below the optical phonon...

Analysis of polarization drift of optical signals over deployed aerial-inground fiber connections

Polarization measurements of a classical 1550-nm signal are collected and analyzed on 15-km hybrid aerial-inground fiber connections over 11 months. The spectral area and spectral moments9 of mHz-resolution Fast-Fourier-Transform (FFT) of these measurements are extracted, and related to temperature, humidity, wind speed, and time of day. Spectral area correlations show a str...

Operational Collapse Region in Repeaterless Loss-Dephasing Quantum Channels

The distribution of entangled photon pairs over standard optical fiber is a fundamental requirement for the realization of the quantum internet. However, real-world deployment is severely bottlenecked by the interplay of amplitude damping (photon loss) and phase noise (birefringence). In this paper, we numerically investigate the degradation of dual-rail polarization entangl...

Quantum Software Engineering in Practice: FPGA and AI Integration for Quantum Certification

The emergence of Quantum Software Engineering (QSE) responds to the need for systematic, disciplined, and quantifiable approaches to the development, operation, and maintenance of quantum software. Within this context, quantum computer certification represents a significant challenge: verifying that quantum devices produce valid entangled states despite hardware imperfection...

Geometric Interpretation of Sum Photon Blockade

We present a geometric interpretation of the sum photon blockade effect in multimode quantum optical systems, such as semiconductor microresonators. The blockade condition c^((n)) ·v = 0 reflects the orthogonality of the n-photon amplitude vector to a target mode vector in an N-dimensional Hilbert space, visualized as the confinement of the state to a hyperp...

Vacuum polarization and renormalized stress-energy tensor of spherical thin shells

We provide a thorough study of the properties of the Boulware vacuum in the spacetime of a spherical, static thin shell with a Minkowski interior. To this end, we calculate the renormalized vacuum polarization and stress-energy tensor of massless scalar fields via the extended-coordinate prescription, paying particular attention to their scaling as the shell approaches the b...

Analysis of the sample complexity for PAC-learning functions defined over quantum states

A fundamental question in PAC learning is determining the number of labeled examples required to learn a concept class to a desired accuracy and confidence. In classical learning theory, this quantity is characterized by the VC-dimension, while several quantum generalizations have established analogous results when examples are provided in quantum superposition. In this work...

Does Born Rule Imply Unitarity of Time Evolution in Quantum Mechanics?

The Born rule for computing probabilities of the outcomes of measurements is an indispensable ingredient of quantum mechanics. The standard textbook description of this rule gives the impression that it implies the unitarity of time evolution. This view relies on the argument that unless the dynamics is unitary, the probabilities of finding all possible outcomes of a measure...

Entanglement Asymmetry in Random Quantum Automata

We investigate the subsystem entanglement asymmetry in random quantum automaton ensembles, which are generated by permuting the basis states in the Hilbert space and applying global phase shifts. We compute the ensemble average of the U(1) subsystem asymmetry in different connectivity geometries, showing that the late-time limit of the ensemble associated to a 2-local circ...

Control Protocols for Entangling Gates for Group-IV Color-Centers in Diamond

Accurately controlling entangling gates remains a major challenge for quantum technology applications with solid-state spin qubits. Here, we study a group-IV color-center with a strongly-coupled nuclear spin and approach the problem from a quantum control perspective. We show that there are three different types of entangling gates where the entanglement is mediated by the p...

Towards Minimax Estimation of High-Order Functionals by Quantum Arguments

We propose a novel approach to the minimax estimation of high-order functionals from the perspective of quantum computing. Specifically, for any real number α≫1, we present two estimators, one for the classical functional F_α(P) = Σ_(i=1)^S p_i^α of a discrete distribution P and the other for the quantum functional F_α(ρ) = tr(ρ^...

A Dynamic Multiplexing Policy for a Quantum Repeater

We consider a multiplexed quantum repeater that distributes entanglement between two end nodes. Multiplexing is achieved through optical integration of many quantum chips. Each chip hosts an optically addressable communication qubit and a separate memory qubit. The communication qubit serves as an entanglement generation interface between different quantum chips, and the mem...

The NISQ Trap: Eight Years of Demonstrations the Hardware Was Built to Lose

With a single contested exception, every NISQ-era flagship demonstration of "quantum advantage" has been classically reproduced, or closed by a simulability theorem, within eighteen months of its announcement. Six theoretical results from 2024 through April 2026 explain the pattern: the regions of circuit-space NISQ hardware can run with sufficient fidelity coincide with the...

Spin Textures and Eigenstate Evolution of Isospectrally Patterned Lattices

Isospectrally patterned lattices exhibit a composite band structure with a tunable ratio of localized versus delocalized eigenstates that is controlled by the underlying phase gradient. We show that the lattice Hamiltonian can be interpreted as that of a single spin exposed to a rotating magnetic field which is allowed to hop with a spin-flip across the lattice. In the low-...

Phase-Programmable Free Electron Quantum States in Synthetic Momentum Space

Light-electron interactions generate synthetic momentum-space dynamics that can be used to engineer free electron quantum states. Here we develop coherent control protocols in which the optical phase acts as the controllable hopping phase of a Floquet-Bloch momentum lattice. Pontryagin optimization designs phase-only waveforms that prepare selected momentum populations and c...

Resource-Efficient Hybrid Quantum Neighborhood Selection for Large-Scale Molecular Diversity Optimization

Large-scale combinatorial optimization remains demanding for classical heuristics, particularly when dense Quadratic Unconstrained Binary Optimization (QUBO) formulations induce large memory footprints, high CPU utilization, and long execution times. While near-term quantum processors cannot yet deliver unconditional quantum advantage, hybrid architectures can provide practi...

Non-Abelian Thouless pumping based on the global adiabatic criterion in Rydberg synthetic lattices

We study a quantum implementation of non-Abelian Thouless pumping in Lieb lattices using Rydberg synthetic dimensions. The lattice is encoded in twelve selected microwave-coupled Rydberg levels, forming a three-cell structure with six degenerate zero-energy states. These zero-energy states define the working subspace for cyclic modulation of the microwave couplings, while th...

Density effects in precision laser spectroscopy of exotic helium atoms

Exotic helium atoms act as unique atomic traps for heavy, negatively charged particles, protecting them from nuclear annihilation and nuclear capture on timescales long enough to enable high-precision laser spectroscopy. Such measurements serve as stringent tests of three-body quantum electrodynamics and offer a direct route to determining fundamental particle masses. Motiva...

Room-temperature inversionless diamond nitrogen-vacancy electronic spin maser

We propose a method to create a room-temperature maser operating at approximately 2.9~GHz frequency using an ensemble of negatively charged nitrogen-vacancy electronic spins (NV) in diamond, without requiring population inversion. Our method considers a DC magnetic field of a few milli-Tesla (mT) applied along the perpendicular direction of an ensemble of NV spins aligned al...

Phase-Selected Efficient Single-Photon Frequency Conversion via Local Fano Resonance in a Two-Giant-Atom Waveguide-QED System

Efficient single-photon frequency conversion is investigated in a two-giant-atom waveguide-QED system, where a two-level giant atom and a Λ-type three-level giant atom couple to a common one-dimensional waveguide. While the Λ-type atom provides the inelastic channel, the two-level atom induces secondary coherent coupling, creating multi-path interference for the converte...

Spectral Chaos Does Not Determine Quantum Mpemba Crossings

In a symmetry-restoration quantum Mpemba effect, an initial state with stronger local symmetry breaking can lose that memory faster than a state that starts closer to the symmetric manifold. We test whether this local ordering reversal is organized by chaotic thermalization in a clean U(1)-conserving spin chain, comparing spectral level statistics with crossings of the entan...

Quantum Recurrence Plot Algorithm Based on Quantum Principal Component Analysis

Recurrence Plot (RP) is a method employed to analyze the periodicity, chaoticity, and nonlinear characteristics of complex systems. Quantum Principal Component Analysis (QPCA), on the other hand, achieves dimensionality reduction of sample data using density matrices based on quantum circuits. We improve the distance threshold function of the recurrence plot algorithm using...

Absolute frequency measurement of the ^(176)Lu^+ (^3D_1) standard against the NRC-FCs2 fountain with 2.6×10^(-16) uncertainty

We report an improved absolute frequency measurement of the ^(176)Lu^+ (^3D_1) optical frequency standard, evaluated via a remote link to the NRC-FCs2 caesium fountain primary frequency standard. Operating a single ion clock with 94.2% uptime over 10 days, and using an ambiguity-resolved precise point positioning (PPP-AR) link over the Global Positioning Syst...

Bayesian Gill-Massar Bound: An Attainable Lower Bound for Qubit Parameter Estimation

We study lower bounds for Bayesian quantum parameter estimation, with a particular focus on qubit models. While several lower bounds on the Bayes risk have been proposed, including the Bayesian symmetric logarithmic derivative (B-SLD) type bound and the Bayesian Nagaoka-Hayashi (B-NH) bound, there is no definite proof available to show they are attainable except for special...

Operator-frame geometry of non-compact quantum systems with frame-vacuum phase transitions

We formulate the geometric structure of non-compact bosonic quantum systems in regimes where vacuum instability renders the relevant quantum states non-normalizable, causing conventional state-space quantum geometry -- described by the Berry connection, curvature, and quantum metric -- to become ill-defined. To overcome this breakdown, we develop a formulation of quantum geo...

Tomography of a Macroscopic Quantum State influenced by Classical Self-Gravity

Macroscopic optomechanical systems offer a promising testbed for distinguishing whether gravity acts as a quantum interaction or as a classical field. Schrodinger-Newton (SN) theory is the nonrelativistic limit of semi-classical gravity where quantum matter couples to classical gravity. Based on SN theory, this work investigates how classical self-gravity affects continuous...

CSIRO Engineers Deploy Field-Ready Quantum Light Sources for Secure Ground-to-Satellite Time Transfer

The Commonwealth Scientific and Industrial Research Organisation (CSIRO), Australia’s national science agency, has engineered and delivered two field-ready Quantum Light Sources to support defense timing synchronization networks. Developed for a defense program managed by the Defence Science and Technology Group (DSTG) in Adelaide, the portable hardware modules act as hig...

BTQ Technologies Finalizes Full Acquisition of QPerfect to Establish Unified Quantum Infrastructure and Security Ecosystem

BTQ Technologies Corp. (Nasdaq: BTQ | Cboe CA: BTQ) has officially finalized its full acquisition of French quantum software developer QPerfect SA. Following the receipt of regulatory foreign direct investment (FDI) clearance from the French Ministry for the Economy and Finance, BTQ exercised its definitive option to absorb the remaining outstanding securities of the Stra...

ETH Zurich Demonstrates Quantum Computer Architecture With Mechanical Working Memory

White House Quantum Summit Exclusive: America’s Commitment to a Quantum Future

BTQ Technologies Completes Acquisition of QPerfect to Expand Quantum Software Capabilities

CSIRO Builds Quantum Light Sources to Counter GPS Jamming and Spoofing

IQM to Deliver Quantum Computer for Europe’s LUMI AI Factory