Phase III of the Qubit Delusion series. Examines fundamental physical limits on computation: Landauer bound, Margolus-Levitin theorem, Bremermann limit, Bekenstein bound. Shows that quantum error-correction overhead (1e2-1e3 physical operations per logical operation) multiplies thermodynamic cost beyond what any polynomial algorithmic speedup can overcome. Proposes a falsifiable criterion: joules per solution on commercially relevant problems. Assesses all major quantum platforms against this criterion. Identifies reversible computing as the only paradigm that can approach the true physical limits. Full text and updates: https://papers.qnfo.org/papers/paper-physics-of-computation/
Phase III of the Qubit Delusion series. Examines fundamental physical limits on computation: Landauer bound, Margolus-Levitin theorem, Bremermann limit, Bekenstein bound. Shows that quantum error-correction overhead (1e2-1e3 physical operations per logical operation) multiplies thermodynamic cost beyond what any polynomial algorithmic speedup can overcome. Proposes a falsifiable criterion: joules per solution on commercially relevant problems. Assesses all major quantum platforms against this criterion. Identifies reversible computing as the only paradigm that can approach the true physical limits. Full text and updates: https://papers.qnfo.org/papers/paper-physics-of-computation/
We establish a unified framework for understanding the fundamental physical limits of computation by developing a geometric theory of resource trade-offs. Our approach treats computation as a physical process constrained by thermodynamics, quantum mechanics, and relativity, leading to a multidimensional capacity region in resource space. We prove that any algorithm achieving error ε on problem class P must satisfy joint constraints across five dimensions: space S, time T, bandwidth H, energy E, and coherence C. The capacity region is characterized by fundamental physical constants: Landauer’s principle (kBT ln 2 per bit erasure), the Margolus-Levitin quantum speed limit (2E/(π~) operations per second), the Bekenstein bound (maximum information density), and statistical sampling limits. We provide explicit constructions showing these bounds are achievable within constant factors for canonical problems including matrix multiplication, covariance estimation, and Gaussian process inference. This framework unifies classical complexity theory with quantum information and thermodynamics, providing the first general theory of multi-resource computational limits with applications to algorithm design, hardware optimization, and fundamental physics.
Abstract: This analysis argues that Shor’s algorithm, while mathematically elegant, functions as a theoretical artifact defined under physically unrealizable conditions—perfect coherence, infinite precision, and unbounded resources—rendering it a mathematical trap that has misdirected the field toward infeasible engineering goals. In contrast, Landauer’s principle—that “information is physical”—provides a necessary foundation for evaluating computation within thermodynamic and material constraints. Empirical evidence reveals a fundamental scaling phase transition: beyond current scales, quantum error correction fails to suppress errors due to correlated failures, operator imprecision, and material defects, causing system reliability to degrade. The resulting divergence in resource requirements makes commercial-scale quantum computing physically infeasible. A constructive path forward requires abandoning idealized models of exponential speedup and developing computational paradigms intrinsically grounded in physical law. Keywords: Quantum computing; Shor’s algorithm; Landauer’s principle; Quantum error correction; Computational scalability; Fault-tolerant quantum computing; Physical limits of computation; Decoherence; Two-level systems; Operator imprecision; Phase transition in quantum systems; Quantum hardware; Information theory; Thermodynamics of computation; Quantum supremacy
This paper argues that quantum computing is not merely "5-10 years away" but fundamentally impossible. It identifies three foundational lies: (1) qubits can be identical (no two qubits are physically identical), (2) superposition represents actual simultaneous states (it is epistemic uncertainty), (3) entanglement enables faster-than-classical computation (it is mere correlation). It then presents twelve fatal barriers that make practical quantum computers impossible: no-cloning theorem prevents error correction at scale, Bell violations prove only correlation not computation, calibration overhead scales exponentially, quantum volume metrics are dishonest marketing, thermodynamic costs are astronomical, hybrid algorithms are classical with quantum noise, limited connectivity destroys parallelism, decoherence-free subspaces are too small, reproducibility crisis signals fraud, economic sunk costs create Ponzi dynamics, treating the wavefunction as ontological is a category error, and the measurement bottleneck violates information theory (Shannon). Each barrier is individually fatal. Together they form an impenetrable wall. The paper concludes that quantum computing is a billion-dollar delusion and recommends redirecting funding to classical alternatives that actually work
Quantum error correction (QEC) is widely regarded as the indispensable cornerstone for achieving scalable, fault-tolerant quantum computation. However, conventional fault-tolerance theorems traditionally rely on abstract circuit models that frequently abstract away fundamental physical laws, treating noise channels and error syndromes as purely mathematical parameters. In this paper, we establish the Physical Limit of Quantum Error Correction (PLQEC) framework, investigating whether there exists an absolute, nature-imposed lower bound on the residual error probability, denoted as p_min, below which reliable quantum information preservation becomes physically unattainable due to deeply rooted thermodynamic, informational, and spacetime constraints. By systematically integrating Landauer's principle, von Neumann entropy bounds, the intrinsic thermodynamics of quantum measurement, and holographic gravity principles, we derive universal fundamental limits on quantum error correction thresholds. We demonstrate that physical constraints such as minimal energy dissipation per syndrome extraction cycle, quantum speed limits, decoherence velocities, and spacetime curvature cutoffs impose strict, unyielding boundaries on fault-tolerant quantum architectures. This work bridges the profound gap between abstract quantum information theory and fundamental physical law, opening a new frontier in understanding the ultimate operational boundaries of quantum information processing in our physical universe.
Companion paper to "The Qubit Delusion" (v1.1, 10.5281/zenodo.21254143). If the qubit-gate-circuit model is an epistemic failure — a projection of particle ontology onto relational, field-theoretic reality — what comes next? We strip quantum mechanics to its minimal ontological commitments, survey alternative paradigms (MBQC, CV-QC, TQC, field-theoretic, analog) for ontological fidelity, assess commercial manufacturability of each physical platform, and ask whether "quantum computing" is even the right frame. The deeper lesson — that computation IS a physical process and the substrate IS the algorithm — points toward thermodynamic, neuromorphic, and optical architectures where physics does the computing directly.
The amount of heat generated by computers is rapidly becoming one of the main problems for developing new generations of information technology. The thermodynamics of computation sets the ultimate physical bounds on heat generation. A lower bound is set by the Landauer limit, at which computation becomes thermodynamically reversible. For classical computation there is no physical principle which prevents this limit being reached, and approaches to it are already being experimentally tested. In this paper we show that for quantum computation with a set of signal states satisfying given conditions, there is an unavoidable excess heat generation that renders it inherently thermodynamically irreversible. The Landauer limit cannot, in general, be reached by quantum computers. We show the existence of a lower bound to the heat generated by quantum computing that exceeds that given by the Landauer limit, give the special conditions where this excess cost may be avoided, and provide a protocol for achieving the limiting heat cost when these conditions are met. We also show how classical computing falls within the special conditions.