Moravian-Silesian Region
Resource-Efficient Variational Quantum Classifier
Ptáček, Petr, Lewandowska, Paulina, Kukulski, Ryszard
Quantum computing promises a revolution in information processing, with significant potential for machine learning and classification tasks. However, achieving this potential requires overcoming several fundamental challenges. One key limitation arises at the prediction stage, where the intrinsic randomness of quantum model outputs necessitates repeated executions, resulting in substantial overhead. To overcome this, we propose a novel measurement strategy for a variational quantum classifier that allows us to define the unambiguous quantum classifier. This strategy achieves near-deterministic predictions while maintaining competitive classification accuracy in noisy environments, all with significantly fewer quantum circuit executions. Although this approach entails a slight reduction in performance, it represents a favorable trade-off for improved resource efficiency. We further validate our theoretical model with supporting experimental results.
cb70ab375662576bd1ac5aaf16b3fca4-AuthorFeedback.pdf
We thank all reviewers for the time they invested to review this paper and share their insights. We have conducted experiments on real-world data, yet could not include them within page limits. Publication of the algorithm in an implemented code (e.g. Java as stated in Line 304). The pseudocodes are given below.
Quantum Neural Networks for Propensity Score Estimation and Survival Analysis in Observational Biomedical Studies
Novák, Vojtěch, Zelinka, Ivan, Přibylová, Lenka, Martínek, Lubomír
This study investigates the application of quantum neural networks (QNNs) for propensity score estimation to address selection bias in comparing survival outcomes between laparoscopic and open surgical techniques in a cohort of 1177 colorectal carcinoma patients treated at University Hospital Ostrava (2001-2009). Using a dataset with 77 variables, including patient demographics and tumor characteristics, we developed QNN-based propensity score models focusing on four key covariates (Age, Sex, Stage, BMI). The QNN architecture employed a linear ZFeatureMap for data encoding, a SummedPaulis operator for predictions, and the Covariance Matrix Adaptation Evolution Strategy (CMA-ES) for robust, gradient-free optimization in noisy quantum environments. Variance regularization was integrated to mitigate quantum measurement noise, with simulations conducted under exact, sampling (1024 shots), and noisy hardware (FakeManhattanV2) conditions. QNNs, particularly with simulated hardware noise, outperformed classical logistic regression and gradient boosted machines in small samples (AUC up to 0.750 for n=100), with noise modeling enhancing predictive stability. Propensity score matching and weighting, optimized via genetic matching and matching weights, achieved covariate balance with standardized mean differences of 0.0849 and 0.0869, respectively. Survival analyses using Kaplan-Meier estimation, Cox proportional hazards, and Aalen additive regression revealed no significant survival differences post-adjustment (p-values 0.287-0.851), indicating confounding bias in unadjusted outcomes. These results highlight QNNs' potential, enhanced by CMA-ES and noise-aware strategies, to improve causal inference in biomedical research, particularly for small-sample, high-dimensional datasets.
An entropy-optimal path to humble AI
Bassetti, Davide, Pospíšil, Lukáš, Groom, Michael, O'Kane, Terence J., Horenko, Illia
Progress of AI has led to a creation of very successful, but by no means humble models and tools, especially regarding (i) the huge and further exploding costs and resources they demand, and (ii) the over-confidence of these tools with the answers they provide. Here we introduce a novel mathematical framework for a non-equilibrium entropy-optimizing reformulation of Boltzmann machines based on the exact law of total probability. It results in the highly-performant, but much cheaper, gradient-descent-free learning framework with mathematically-justified existence and uniqueness criteria, and answer confidence/reliability measures. Comparisons to state-of-the-art AI tools in terms of performance, cost and the model descriptor lengths on a set of synthetic problems with varying complexity reveal that the proposed method results in more performant and slim models, with the descriptor lengths being very close to the intrinsic complexity scaling bounds for the underlying problems. Applying this framework to historical climate data results in models with systematically higher prediction skills for the onsets of La Niña and El Niño climate phenomena, requiring just few years of climate data for training - a small fraction of what is necessary for contemporary climate prediction tools.
ReLCP: Scalable Complementarity-Based Collision Resolution for Smooth Rigid Bodies
Palmer, Bryce, Aktulga, Hasan Metin, Gao, Tong
We present a complementarity-based collision resolution algorithm for smooth, non-spherical, rigid bodies. Unlike discrete surface representation approaches, which approximate surfaces using discrete elements (e.g., tessellations or sub-spheres) with constraints between nearby faces, edges, nodes, or sub-objects, our algorithm solves a recursively generated linear complementarity problem (ReLCP) to adaptively identify potential collision locations during the collision resolution procedure. Despite adaptively and in contrast to Newton-esque schemes, we prove conditions under which the resulting solution exists and the center of mass translational and rotational dynamics are unique. Because increasing the surface resolution in discrete representation methods necessitates subdividing geometry into finer elements--leading to a super-linear increase in the number of collision constraints--these approaches scale poorly with increased surface resolution. In contrast, our adaptive ReLCP framework begins with a single constraint per pair of nearby bodies and introduces new constraints only when unconstrained motion would lead to overlap, circumventing the oversampling required by discrete methods. By requiring one to two orders of magnitude fewer collision constraints to achieve the same surface resolution, we observe 10-100x speedup in densely packed applications. We validate our ReLCP method against multisphere and single-constraint methods, comparing convergence in a two-ellipsoid collision test, scalability and performance in a compacting ellipsoid suspension and growing bacterial colony, and stability in a taut chainmail network, highlighting our ability to achieve high-fidelity surface representations without su ff ering from poor scalability or artificial surface roughness. Keywords: Rigid body dynamics, Nonsmooth dynamics, Linear complementarity problem, Collision resolution, ReLCP 1. Introduction The simulation of collision and contact dynamics in rigid and flexible body systems has a rich and extensive history in scientific computing, engineering, and computer graphics. Methods for managing frictional contact and resolving collisions can be broadly categorized into three types: piecewise-smooth, smooth (penalty-based), and nonsmooth (complementarity-based) methods. Piecewise-smooth approaches focus on identifying the precise times and locations of collision events, applying instantaneous impulses to uphold the conservation of momentum. While these methods are conceptually straightforward and lend themselves well to analytical treatment, they are rarely employed in large-scale simulations.