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609 papers from the QNFO program, filed on nine shelves by the reader each one is written for: energy per answer, error correction, physics, numbers and p-adics, logic and formalism, AI and knowledge, autonomous systems, assessments, and cross-cutting essays. Every page renders its mathematics and can be questioned in place. How a living paper works.
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Qubits papers 19 papers
Qubits. Qubit devices, control and readout Tagged papers: 19.
Two-Level System Defects as a Random Ensemble: Counting and Dephasing Estimates for Superconducting Qubits
Parasitic two-level system (TLS) defects in the amorphous tunnel barriers of superconducting qubits are a major identified source of decoherence, yet device designers lack closed-form estimates linking defect density and junction geometry to the probability that a device is degraded and to the…
A Cost-Model Benchmark for Mixed-State Quantum Simulation Workloads: Entanglement-Cost Anchors and Reuse-Aware Re-Entry Metrics
Classical simulation of quantum circuits increasingly takes the form of repeated-run workloads—variational-parameter sweeps, noisy multishot studies, and error-correction cycles—rather than isolated executions, and the target states of such workloads are frequently mixed rather than pure. This paper…
Operational Circularity of Qubit Ontology: Excitations Defined by Their Own Readout
Is the qubit a pre-existing object that control pulses and readout merely probe, or a two-level subsystem constituted by the very operations that define it? We formalize this question as a self-referential calibration problem: an ontology map $\Phi$ assigns Hilbert-space identifications to…
Semantic Fidelity: An Operational Measure for Borrowed Quantum Terms and the Scale at Which They Fail
Quantum computing borrows its vocabulary from quantum optics, condensed matter, and particle physics, and this borrowed ontology can quietly conflict with the operational content of the circuit model it is meant to describe. We propose an operational quantity, semantic fidelity $F_S$, defined as one…
The Exponential Arena: A Reconciled Quantitative Account of Hilbert-Space Growth with Qubit Number
A recurring question in quantum information is what "space" the state of a quantum computer inhabits, and how that space grows as the number of qubits $n$ increases. This paper treats the question quantitatively, formalizing the arena of an $n$-qubit register as the complex projective Hilbert space…
Measurement-and-Feedforward Quantum Circuits as Code Design: Detectability, Branch Counting, and the Location of Nonstabilizerness
Shallow quantum circuits augmented by mid-circuit measurements and classical feedforward can deterministically prepare long-range entangled states and implement global unitaries that no comparable-depth unitary circuit can reach. Recent work established a general correspondence between all such…
Adaptivity Closes the Stabilizer Learning Gap: An Analytical Account of Optimal Single-Copy Stabilizer State Learning
Stabilizer states underpin quantum error correction, device benchmarking, and the classical simulation of quantum circuits, yet their learnability shows a sample-complexity gap: an $n$-qubit stabilizer state can be identified from $\Theta(n)$ copies using joint two-copy Bell measurements, while…
Low-Overhead Quantum Error Correction with Boundary-Connected Planar Modules: A Reconciled Quantitative Assessment
The planar surface code protects quantum information robustly but pays for its two-dimensional layout with an encoding rate that vanishes as the distance grows, so fault-tolerant memories require hundreds to thousands of physical qubits per logical qubit. A recent proposal constructs modular…
Beyond Pure Dephasing: A Quantitative Analysis of Two-Level Error Correction for Multi-Spin Molecular Qubits
Molecular spin systems exhibit a natural hierarchy of decoherence channels: fast pure dephasing (characterized by the transverse relaxation time T₂) and comparatively slow energy relaxation (characterized by T₁). A recent proposal argues that fault-tolerant quantum computing with molecules requires…
Constant-Sized-Support Magic State Distillation with Qubit Recycling: A Reconciled Resource, Footprint, and Energy Analysis
Magic state distillation (MSD) is the canonical route to non-Clifford gates in fault-tolerant quantum computation, but conventional nested factories exhibit qubit occupancy that grows multiplicatively with the number of distillation rounds. Recent work on constant-sized-support distillation…
Trapped-Ion Qudit Quantum Computing: Due-Diligence Assessment of the Ringbauer Program
Due-diligence research note assessing the trapped-ion qudit quantum computing program led by Martin Ringbauer at the University of Innsbruck. Records the universal qudit processor (2022), the native qudit entanglement gate based on a generalized light-shift mechanism (2023), and the lattice gauge…
The Valuation Reading of the Qubit Delusion: Is the Adelic Kernel Load-Bearing?
The Qubit Delusion (https://papers.qnfo.org/papers/paper-the-qubit-delusion/) argues that the qubit-gate-circuit model of quantum computation imports a particle ontology inconsistent with quantum field theory, and that the field's failure to deliver commercially viable hardware after $35 billion of…
Bosonic Codes as the Native Encoding: Resource-Commensurable Comparison of Cat, GKP, Binomial, and Surface Codes
X3.3 — Resource-commensurable comparison of bosonic codes vs surface codes using photons/logical-qubit metric at p_L=10^-6. Bosonic codes require 5-40x fewer photons and ~100x fewer modes. Novel claim: HO as QM IR attractor implies bosonic codes are the native encoding.
No Thing There: Control, Readout, and Self-Referential Metrology in Engineered Quantum Systems
Pedagogical bridge between qubit ontology critique and working physics. Explains what control pulses actually manipulate and what readout measures, across superconducting transmon, trapped-ion, and spin qubit platforms. Includes electrical seesaw analogy, self-referential metrology formalization,…
The Revolutionary Beginner's Guide to Quantum Computing: Why We Don't Have Quantum Computers Yet — and What the Geometric Alternative Offers
A 20-chapter beginner's guide to quantum computing that starts with an honest question — why don't we have quantum computers yet? — rather than the usual "here's what a qubit is." The guide teaches the standard curriculum (qubits, entanglement, algorithms, error correction) accurately, explains why…
Shor's Algorithm and the Unproven Premise: An Assumption Audit of the Quantum Factoring Narrative
Shor's 1994 algorithm proves FACTORING ∈ BQP, but the claim that this constitutes a quantum advantage requires the additional unproven premise FACTORING ∉ BPP. This paper decomposes Shor's claim architecture into nine assumptions spanning number theory, computational complexity, and quantum physics.…
Tweezers Magnet
The dominant paradigm in advanced computing, particularly in the quantum domain, relies on the precise external control of individual, fragile information carriers—a particle-centric approach analogous to arranging iron filings with tweezers. This method is fundamentally constrained by its reliance…
Computational Benchmark of Geometric and Algebraic Models for Multi-Qubit State Representation
The Bloch sphere provides a powerful yet fundamentally limited geometric model for quantum states, excelling at single-qubit intuition but failing to represent the multi-qubit entanglement that powers quantum advantage. This work addresses the critical tension between the cognitive simplicity of…
Continuous Signal Processing for Josephson Junction Readout
The prevailing architecture of superconducting quantum information processing relies heavily on the Josephson junction, yet its dual role as both a qubit-defining non-linear inductor and a latching readout element creates a fundamental tension in measurement dynamics. While the former enables the…
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