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• IBM Connects Two 120-Qubit Chips With 99% State Transfer

  IBM researchers link two 120-qubit Nighthawk R1 processors with four superconducting coaxial cables and report 99.00% mean fidelity for quantum state transfer. The links also support distant gates and entangled states, though controlled-Z gates across the processors average 94.75% fidelity.

• Ott and Colleagues Use Logical Qubits to Find Rare Signals in Noise

  A Physical Review Letters paper by Robert Ott and colleagues proposes quantum error correction for detecting weak, randomly timed signals amid local noise. Its analysis and simulations find an advantage over conventional sensing in specified regimes, while identifying fast, reliable error correction as a practical requirement.

• Waterloo Researchers Set a Direct-Link Ceiling for Gaussian Repeaters

  A Physical Review Letters paper by University of Waterloo researchers finds that Gaussian repeater chains cannot beat direct transmission over a pure-loss optical channel. The proof covers Gaussian operations, homodyne measurements and classical communication, and introduces a fractional-extendibility method for analyzing the limit.

• 125-Qubit Processor Teleports Surface-Code States at Distance Seven

  A superconducting processor with 125 qubits demonstrated teleportation of surface-code states at code distance seven, using 98 qubits in two interlaced blocks. Because hardware feedback was unavailable, the researchers postponed Alice’s measurement and used CNOT gates in place of classical communication.

• Aarhus Spectrometer Learns DNP Pulses on the Sample

  Aarhus researchers used Bayesian optimization to design dynamic nuclear polarization pulse sequences by testing them directly on samples in a spectrometer. The method produced results comparable to an established sequence in a trityl test and a 70% signal-enhancement gain over a reference in a nitroxide experiment.

• Cloudflare Puts Post-Quantum GeoKey Manager Into Closed Beta

  Cloudflare has launched a closed beta of a post-quantum GeoKey Manager that restricts where customer decryption keys can be used. The system combines ML-KEM-768 and X25519, with general availability planned for the first quarter of 2027.

• GaAs Triple Dot Delivers 4.05-Nanosecond Spin Gates

  A GaAs triple-quantum-dot experiment reports a 99.56% fidelity single-spin π/2 gate completed in 4.05 nanoseconds. The design uses a third-dot tuning control and neural-network feedback to address slow qubit-frequency drift.

• Researchers Build a Quantum Measurement Model for Axion Searches

  Six researchers present a fully quantum model of continuous axion-dark-matter measurements in cavity haloscopes. Their calculations predict photon-count statistics that differ from the Poisson model often used for coherent signals, while finding that intrinsically nonclassical axion effects remain out of reach.

• Hartree Theory Fails for Some Non-Hermitian Boson Dynamics

  A paper in Quantum finds that the Hartree approximation can fail to describe bosonic many-body dynamics governed by non-Hermitian Hamiltonians. The authors demonstrate the problem in solvable and numerical examples, including a model whose one-particle state becomes mixed at a finite time.

• Rocq and Lean Teams Formalize BB84 Security in Separate Proofs

  A Rocq paper submitted October 22 reports a machine-checked proof of composable, finite-key security for BB84, after an earlier Lean paper described an end-to-end security theorem for a specific BB84 formulation. The papers use different proof assistants and approaches; the Lean abstract reports a reduction in the finite-size penalty on the key rate, but makes no priority claim.

• Zirconium Aryloxides Demonstrate Coherent Control for Qudits

  A study in Nature Chemistry reports coherent control of spin transitions in three zirconium(III) molecules, including transitions coupled to the zirconium-91 nucleus. The findings point to possible molecular qudits, quantum systems with more than two controllable states.

• SEEQC Reports 50% QEC Gains in a Simulated Decoder Stack

  SEEQC says a simulated architecture combining its chip-based pre-decoder with NVIDIA Ising reduced decoding latency and improved logical-error performance by approximately 50% compared with NVIDIA Ising used alone as a pre-decoder. The company describes SEEQC’s pre-decoder as a backend to NVIDIA Ising Decoding; the result was not a demonstration on a running quantum processor.

• A New Paper Sets Lower Bounds on Quantum Measurement Memory

  A study of exact quantum-measurement storage derives lower bounds on how quantum and classical memory can be divided. It also describes protocols whose memory requirements depend on how the measurement is accessed and on the target success probability.

• Stuttgart-Led FeedbacQ Wins €1.15m for Quantum Control

  A three-year European project led by the University of Stuttgart will investigate whether control theory can help quantum computers tackle optimization problems and reduce errors. The six-partner team plans to develop algorithms and test its methods on quantum hardware, including a gate-based device in Turin.

• Phasecraft AI Agents Cut Costs Across Three Quantum Benchmarks

  Researchers report lower measured costs across three quantum-simulation compilation tasks using AI agents paired with frozen verifiers. The results concern benchmark resource counts, not demonstrations on quantum hardware.

• Kun Wang Uses Adaptive Checks to Bound Stabilizer Fidelity

  Kun Wang’s paper describes an adaptive method for narrowing the range of fidelities consistent with stabilizer measurements. Simulations reported in the paper compare the method with uniform random gauge selection, while also examining how finite measurement samples affect the certified intervals.

• 56-Qubit H2-2 Test Reveals Bosonic Encoding Trade-Offs

  A study posted October 21 compares three qubit encodings for bosonic simulation and tests unary and Dicke circuits on Quantinuum’s 56-qubit H2-2. Classical simulations favor binary quadrature for its space efficiency, but the team did not run that encoding on the device.

• Bechtle Adds IQM Quantum Systems to DLR Initiative

  Bechtle will provide the German Aerospace Center’s Quantum Computing Initiative with cloud-based access to IQM superconducting quantum systems through June 2027. The agreement also includes a dedicated server at IQM’s Munich data centre for conventional computing and hybrid workloads.

• hBN Defects Hold Nuclear-Spin Coherence for Up to 1.44 Milliseconds

  Researchers report shell-selective control of boron nuclei around defects in hexagonal boron nitride, with Hahn-echo coherence times ranging from 0.33 to 1.44 milliseconds. The findings describe a layered spin system, not a demonstrated quantum memory.

• NQCC Completes Deployment of Seven Quantum Testbeds

  The NQCC’s £30 million testbed programme completed its first phase with seven quantum systems delivered by the end of 2025. The centre and the University of Edinburgh’s Quantum Software Lab are now evaluating the systems across five hardware approaches.

• Quantum X Reports 12.7% Fewer Errors on Google Data

  Quantum X Labs says its decoder produced fewer logical errors than PyMatching on Google’s public surface-code data in both a five-round test and a separate streaming evaluation. The company says it plans to test the decoder in a real-time pipeline using NVIDIA NVQLink; the reported benchmarks used released data, not a live quantum processor.

• Israeli Quantum Companies Raised Nearly $500 Million in 2025

  Israeli quantum companies raised nearly $500 million in private investment in 2025, about 9% of the global total, according to a report released by the Israel Innovation Authority and C4IR Israel. The report counts more than 20 active companies and about 1,000 workers, while warning that adoption beyond defense, aerospace and secure communications remains limited.

• IBM Team Entangles Logical Qubits on Nighthawk Processor

  Researchers report entangling two logical qubits on a 120-qubit superconducting processor, with Bell-state fidelity above 93%. Their experiments also show how excluding underperforming components improved a distance-5 surface code and how fast resets helped stabilize repeated measurements.

• NQCP Spinout Pelagic Systems Announces Quantum Control Software

  Pelagic Systems announced its launch as a spinout from the Novo Nordisk Foundation Quantum Computing Programme, describing a software platform for measuring, understanding and controlling quantum processors. A separate arXiv paper reports millisecond-scale calibration and benchmarking results from an FPGA workflow tested on a superconducting-qubit processor.

• USTC Researchers Demonstrate Four-Way Multiplexed Quantum Gates

  A paper by researchers affiliated with the University of Science and Technology of China reports parallel control of four single-qubit and four two-qubit gates using frequency-multiplexed signals. The experiment found no statistically significant increase in gate errors after waveform pre-distortion, while larger reductions in control-line count remain projections.

• Jesús Fuentes Aguilar Proposes a Quantum Sensor That Resets After Gain

  A theoretical protocol drives a quantum oscillator through transient parametric gain, then returns it to the vacuum while preserving the signal’s displacement. The paper analyzes the method’s sensitivity and the noise cost of dissipation, but does not report a built or tested sensor.

• Technion Team Steers STM Electrons in 860-Attosecond Bursts

  A Technion-led team used two-color infrared pulses to control electron flow through a scanning tunnelling microscope junction. The researchers report a theory-derived burst duration of 860 attoseconds, with 2-nanometer lateral resolution and sub-ångström height sensitivity.

• Adelaide Team Reworks SQUID Arrays to Detect Zero Field

  Adelaide University researchers report that bare superconducting loops can give SQUID arrays an absolute magnetic-field response without varying the physical areas of their loops. The design addresses a sensitivity trade-off in existing arrays, but still needs further testing before commercialization.

• Bendersky, Gomez and Romero Correct Strong-Drive Qubit Gates

  A paper posted to arXiv on October 29 presents frequency and timing corrections for single-qubit gates driven beyond the rotating-wave approximation. Numerical simulations show at least a thousandfold reduction in Hadamard-gate infidelity at one tested drive setting, while hardware performance remains untested.

• QuEra Details AIST’s ABCI-Q Quantum-HPC Testbed

  AIST’s ABCI-Q combines a GPU supercomputer with four quantum-computing platforms, giving researchers a place to test hybrid workflows. A separate AIST notice requests supplier materials and comments on a planned expansion with AI-computing and AI-agent capabilities.

• Stony Brook Proves Quantum Algorithms Need Exponential Queries for Welded-Tree Paths

  A Stony Brook proof shows that quantum algorithms need at least Ω(2^(n/24)) queries to find a path through a welded tree of height n, even though a quantum walk can find the exit exponentially faster than classical algorithms. A second proof appeared days later, and the research teams are working to determine the optimal lower bound.

• Fuzhou Team Tracks Decoherence Across Eight Environmental Qubits

  A Fuzhou University team tested how a microwave cat state loses and regains interference as its controllable environment grows to eight qubits. The experiment mapped a crossover to apparently irreversible decoherence, with revival suppressed during the observed interval.

• FIU Team Tests Checkpointing for Quantum Neural Networks

  Florida International University researchers are developing checkpoints to help quantum workflows recover after interruptions. Their quantum-neural-network framework requires 186.6 KB of storage for a 100-qubit model, according to the team’s lab page.

• Seven Japanese Groups Start Work on a Distributed Quantum Platform

  Seven organizations in Japan have begun developing a NEDO-backed platform that links quantum computers, Tsurugi database clusters and optical networks. The project targets a scale of hundreds of thousands of qubits and plans to test applications in energy, AI computing and industry.

• Emory Physicists Model Light-Based Detection of Anyons

  Emory physicists Tianhong Lu and Luiz H. Santos modeled exciton–quasihole bound states in a fractional Chern insulator as a possible way to study anyons with light. The paper estimates a binding-energy scale of 0.8–1.2 meV, but does not establish that as the size of an optical shift.

• Delta Gold Raises £1.79 Million for Sensing, Communications and Working Capital

  Delta Gold says it raised £1.79 million to fund sensing and communications work, potential UK university collaborations and general working capital. Its announcement also sets out proposed share admission details, while a separate release describes research programmes at Penn State and the University of Toronto.

• RIT Researchers Model Faster Weak-Force Detection at an Exceptional Point

  A theoretical optomechanical model finds that a weak mechanical force can be detected with the same reliability in less observation time at an exceptional point than in a comparable reference system. The estimated 49.85% time reduction assumes ideal collection of light from the cavity and is not a laboratory result.

• Huang, Yang and Zhou Prove Four Settings Needed for Two-Qubit Moments

  A paper on arXiv establishes that four orthogonal projective measurement settings are necessary and sufficient to estimate nine collective first and second moments of two qubits without bias for arbitrary input states. Its numerical four-setting design comes close to a model-specific variance bound, while separate examples compare shared measurements with other protocols.

• Ma and Shi Tighten Bounds for Quantum Local-Recovery Codes

  For a 20-qudit example, a paper by Shuowei Ma and Fei Shi derives successively tighter upper bounds on the code parameter k, from 6 to 2. Since the code-space dimension is K = q^k, those bounds correspond to K ≤ q⁶, q⁴, q³ and q², with the strongest applying to linear stabilizer codes at minimal locality.

• Telefónica and IQM to Install Madrid’s First Quantum Computer

  Telefónica and IQM plan to install an IQM Spark quantum computer at Universidad Politécnica de Madrid before the end of 2026. The locally hosted system is intended to give researchers, students, hospitals and startups in the Community of Madrid direct access to quantum hardware.