arXiv subjects

Samuel Punch

Publications and source records attributed to Samuel Punch.

6 recordsLinked to original sources

arXiv2026

Quantum Workload Privacy Beyond Data Confidentiality

Remote quantum computing exposes a confidentiality gap. Standard privacy mechanisms protect quantum states and outputs, but not the scientific structure of a workload. This work reveals that hardware-aware compilation leaves observable signatures, such as routing overhead, circuit depth, and gate composition, that correlate with hidden modelling choices like partial differential equation boundary conditions, discretisation scale, and molecular geometry. The leakage arises from the mismatch between logical topology and fixed hardware connectivity, forcing problem-dependent SWAP insertion. We formalise this threat as Scientific-Intent Indistinguishability and prove that passive security is asymptotically unachievable under routing-optimal compilation. Experiments on a 156-qubit IBM Heron processor achieve near-perfect classification of boundary regimes and molecular geometries, with leakage generalising across solver families via routing-scaling exponents. Conventional gate-padding fails as a defence, causing fidelity drops without reducing adversarial advantage. Our results show that protecting quantum data alone is insufficient; execution-level confidentiality must become a first-class design requirement.

cs.ET↗

arXiv2026

Balanced Routing for Symmetric Quantum Circuits

Mapping quantum programs to restricted physical chips requires SWAP operations, incurring depth and error penalties. In symmetric programs, this routing overhead breaks theoretical symmetry because identical logical roles experience unequal shuffling. While often attributed to hardware topology alone, we show this is a two-level phenomenon. A qubit patch's shape dictates if it can host a balanced assignment. When balance is possible, the actual imbalance is set by the logical-to-physical assignment, meaning a balanced assignment can distribute routing costs perfectly evenly at no extra depth. Through exhaustive search on a 57-qubit "heavy-hex" lattice, we prove these topological constraints. For a four-part ring, 108 of 124 connected patches admit a cost-free balanced assignment, with the 16 exceptions being star-shaped. For a six-part ring, cost-free balance is impossible on compact patches. For a fully connected four-part symmetry, balance is structurally impossible at any depth. Simulations using realistic error rates show that, relative to the worst-case concentrated assignment, balanced assignments reduce symmetry-breaking by 92.7% (95% CI [+89.8%, +95.3%]) for the raw metric and 87.0% (95% CI [+79.6%, +94.1%]) for the decoherence-corrected measure (p = 2.45 x 10^-32). Substrate error heterogeneity accounts for at most 10.8% of this effect. Notably, switching to the compiler's highest generic optimization level did not yield a statistically significant change in routing imbalance, highlighting the need for targeted symmetry-aware passes. When patch geometry permits, routing imbalance is a compiler choice rather than a hardware limitation. Thus, symmetry-aware assignment should be a primary objective for compiler optimization and chip design.

quant-ph↗

arXiv2026

Post-Cut Metadata Inference Attacks on Quantum Circuit Cutting Pipelines

Quantum cloud providers can identify a user's algorithm and secret problem structure without ever seeing actual quantum data, simply by analyzing routine metadata collected for billing and system management. Existing confidentiality tools such as blind quantum computation and quantum homomorphic encryption protect the quantum payload itself, but they do not protect this classical orchestration metadata. This leaves an unexplored security risk in the logs generated when a large quantum program is split into smaller pieces to fit onto limited hardware, a process known as circuit cutting. These fragments leak sensitive information through what we term the topological transpilation penalty: the unavoidable depth and gate inflation added when a compiler reorganizes a program for a restricted hardware topology. Tests on a 156-qubit production Quantum Processing Unit (QPU) show that traditional timing side-channels fail in this setting, since hardware control-plane delays mask actual quantum execution time. The unique shape of the transpilation penalty acts instead as a persistent structural fingerprint for the hidden workload. Using 12,000 circuit fragments across eight algorithm families, our attack recovers algorithm family and Hamiltonian k-locality with near-perfect accuracy, achieving instance-disjoint AUC = 1.000 for both. This leakage persists under size-holdout evaluation on unseen circuit scales, with AUC = 0.987 and 0.986 respectively. The cutting mechanism is inferred with AUC = 0.991, and hardware topology is recovered well above chance with AUC = 0.818. These results show that circuit cutting exposes algorithmic intent, and potentially proprietary problem structure, through metadata alone, without any need to observe quantum data.

quant-ph↗

arXiv2025

MAESTROCUT: Dynamic, Noise-Adaptive, and Secure Quantum Circuit Cutting on Near-Term Hardware

We present MaestroCut, a closed-loop framework for quantum circuit cutting that adapts partitioning and shot allocation to device drift and workload variation. MaestroCut tracks a variance proxy in real time, triggers re-cutting when accuracy degrades, and routes shots using topology-aware priors. An online estimator cascade (MLE, Bayesian, GP-assisted) selects the lowest-error reconstruction within a fixed budget. Tier-1 simulations show consistent variance contraction and reduced mean-squared error versus uniform and proportional baselines. Tier-2 emulation with realistic queueing and noise demonstrates stable latency targets, high reliability, and ~1% software overhead under stress scenarios. These results indicate that adaptive circuit cutting can provide accuracy and efficiency improvements with minimal operational cost on near-term hardware.

cs.CR↗

arXiv2025

Adaptive t Design Dummy-Gate Obfuscation for Cryogenic Scale Enforcement

Cloud quantum services can reveal circuit structure and timing through scheduler metadata, latency patterns, and co-tenant interference. We introduce NADGO (Noise-Adaptive Dummy-Gate Obfuscation), a scheduling and obfuscation stack that enforces operational privacy for gate-model workloads by applying per-interval limits on observable information leakage. To support confidentiality and fair multi-tenancy, operators require a method to audit compliance at acceptable overheads. NADGO combines: (i) hardware-aware t-design padding for structured cover traffic, (ii) particle-filter timing randomization to mask queue patterns, (iii) CASQUE subcircuit routing across heterogeneous backends, and (iv) a per-interval leakage estimator with locked calibration artifacts and a dual-threshold kill-switch. We prototype the approach on a 4-qubit superconducting tile with cryo-CMOS control and evaluate both depth-varied local-random circuits and small QAOA instances. Monitoring runs at a 6.3 microsecond control interval, and per-interval decisions are recorded in an append-only, hash-chained audit log. Across Monte Carlo (Tier 1) and cloud-hardware emulation (Tier 2) evaluations, NADGO maintains leakage within budget in nominal operation (interval-abort rate below 1 percent) and under attack yields high separation with concentrated aborts. At matched leakage targets, microbenchmarks indicate lower latency and cryogenic power consumption than static padding, while end-to-end workloads maintain competitive cost envelopes.

cs.CR↗

arXiv2025

Simulating Mass-Dependent Decoherence in Quantum Computers: Baseline Signatures for Testing Gravity-Induced Collapse

We present a quantum computing simulation study of mass-dependent decoherence models inspired by Penrose's gravity-induced collapse hypothesis. According to objective reduction (OR) theory, quantum superpositions become unstable when the gravitational self-energy difference between branches exceeds a certain threshold, leading to a collapse time $\tau \approx \hbar / E_G$. In this work, we implement a mass-dependent dephasing noise channel, $p(m) = 1 - e^{-k m^{\alpha}}$, within the Qiskit AerSimulator, where $m$ is a proxy for the effective mass of a superposition, mapped to circuit parameters such as the number of entangled qubits or branch size. We apply this model to three canonical quantum computing experiments: GHZ state parity measurements, branch-mass entanglement tests, and Grover's search to generate distinctive collapse signatures that differ qualitatively from constant-rate dephasing. The resulting patterns serve as a baseline reference: if future hardware experiments exhibit the same scaling trends under ideal isolation, this could indicate a contribution from mass-dependent collapse processes. Conversely, deviation toward constant-noise behaviour would suggest the absence of such gravitationally induced effects. Our results provide a reproducible protocol and reference for using quantum computers as potential testbeds for probing fundamental questions in quantum mechanics.

quant-ph↗