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Reducing the resources required by ADAPT-VQE using coupled exchange operators a...
Ramôa, Mafalda; Anastasiou, Panagiotis G.; Santos, Luís Paulo; Mayhall, Nicholas J.; Barnes, Edwin; Economou, Sophia E.Adaptive variational quantum algorithms arguably offer the best prospects for quantum advantage in the Noisy Intermediate-Scale Quantum era. Since the inception of the first such algorithm, the Adaptive Derivative-Assembled Problem-Tailored Variational Quantum Eigensolver (ADAPT-VQE), many improvements have appeared in the literature. We combine the key improvements along with a novel operator pool—which we ter...
Trainability issues in quantum policy gradients
Sequeira, André Manuel Resende; Santos, Luís Paulo; Barbosa, L. S.This research explores the trainability of Parameterized Quantum Circuit-based policies in Reinforcement Learning, an area that has recently seen a surge in empirical exploration. While some studies suggest improved sample complexity using quantum gradient estimation, the efficient trainability of these policies remains an open question. Our findings reveal significant challenges, including standard Barren Plat...
Policy gradients using variational quantum circuits
Sequeira, André; Santos, Luís Paulo; Barbosa, L. S.Variational quantum circuits are being used as versatile quantum machine learning models. Some empirical results exhibit an advantage in supervised and generative learning tasks. However, when applied to reinforcement learning, less is known. In this work, we considered a variational quantum circuit composed of a low-depth hardware-efficient ansatz as the parameterized policy of a reinforcement learning agent. ...
Ensemble metropolis light transport
Bashford-Rogers, Thomas; Santos, Luís Paulo; Marnerides, Demetris; Debattista, KurtThis article proposes a Markov Chain Monte Carlo (MCMC) rendering algorithm based on a family of guided transition kernels. The kernels exploit properties of ensembles of light transport paths, which are distributed according to the lighting in the scene, and utilize this information to make informed decisions for guiding local path sampling. Critically, our approach does not require caching distributions in wo...
Optimized voronoi-based algorithms for parallel shortest vector computation
Mariano, Artur; Cabeleira, Filipe; Santos, Luís Paulo; Falcão, GabrielThis chapter addresses Voronoi cell-based algorithms, solving the Shortest Vector Problem, a fundamental challenge in lattice-based cryptanalysis. Several optimizations reduce the original algorithm's execution time. The algorithm suitability for parallel execution on both CPUs and GPUs is also shown. Optimizations are based on pruning, avoiding computations that will not improve the solution. The pruning crite...
Foreword to the special section on recent advances in graphics and interaction
Rodrigues, Nuno; Mendes, Daniel; Santos, Luís Paulo; Bouatouch, KadiThis special section on Recent Advances in Graphics and In- teraction features the papers submitted to Computers & Graphics (C&G) and presented at the 2021 edition of the International Conference on Graphics and Interaction – ICGI’2021 – which was held on November 4 and 5, 2021 at the Faculty of Engineering of the University of Porto, Portugal, as a joint organization with the Eurographics Portuguese Chapter — ...
Interactive VPL-based global illumination on the GPU using fuzzy clustering
Colom, Arnau; Marques, Ricardo; Santos, Luís PauloPhysically-based synthesis of high quality imagery, including global illumination light transport phenomena, results in a significant workload, which makes interactive rendering a very challenging task. We propose a VPL-based ray tracing approach that runs entirely in the GPU and achieves interactive frame rates while handling global illumination light transport phenomena. This approach is based on clustering b...
LOOM: Interweaving tightly coupled visualization and numeric simulation framework
Barbosa, Joao; Navratil, Paul; Santos, Luís Paulo; Fussell, DonaldTraditional post-hoc high-fidelity scientific visualization (HSV) of numerical simulations requires multiple I/O check-pointing to inspect the simulation progress. The costs of these I/O operations are high and can grow exponentially with increasing problem sizes. In situ HSV dispenses with costly check-pointing I/O operations, but requires additional computing resources to generate the visualization, increasin...
Generalised quantum tree search
Sequeira, André Manuel Resende; Santos, Luís Paulo; Barbosa, L. S.This extended abstract reports on on-going research on quantum algorithmic approaches to the problem of generalised tree search that may exhibit effective quantum speedup, even in the presence of non-constant branching factors. Two strategies are briefly summarised and current work outlined.
Quantum tree-based planning
Sequeira, Andre; Santos, Luís Paulo; Barbosa, L. S.Reinforcement Learning is at the core of a recent revolution in Arti cial Intelligence. Simultaneously, we are witnessing the emergence of a new eld: Quantum Machine Learning. In the context of these two major developments, this work addresses the interplay between Quantum Computing and Reinforcement Learning. Learning by interaction is possible in the quantum setting using the concept of oraculization of envi...