Theoretical and Physical Boundaries of Lattice-Based Post-Quantum Cryptography: An Anatomical Critique of QRAM-Hardness Primitives and Thermodynamic Security (Vol-III)
Syed Muntasir Mamun
Abstract
This third volume advances QRAM-hardness cryptography, arguing that the ultimate quantum resilience of lattice-based primitives must be grounded in the thermodynamic lower bounds governing coherent state preparation, rather than transient algorithmic assumptions. While Learning with Errors (LWE) is mathematically susceptible to the Gottesman-Kitaev-Preskill (GKZ) quantum learning algorithm, this paper definitively proves that the index-erasure problem and the construction of a necessary Quantum Random Access Memory (QRAM) oracle impose insurmountable physical barriers. The necessity of reversing classical computation paths to maintain quantum coherence is subject to Landauer's Principle, dissipating a minimum energy of $k_B T \ln 2$ per erased bit. For cryptographically relevant dimensions, the total dissipated energy scales to macroscopic limits, instantly vaporizing cryogenic cooling systems and physically preventing the required Mamun, SM (2026) …………………………….1 Theoretical and Physical Boundaries of Lattice-Based Post-Quantum Cryptography: An Anatomical Critique of QRAM-Hardness Primitives and Thermodynamic Security (Vol-III) $\left|\psi_{s, e}\right\rangle$ superposition state preparation. Furthermore, this heat manifests as non-Gaussian thermodynamic noise, pushing continuous-variable GKP error-correction codes beyond their critical correctable threshold and inducing catastrophic logical failure. Also available on Academia.edu: https://www.academia.edu/attachments/132761250/download_file?s=portfolio