Paper A Theory of Direct Randomized Benchmarking Anthony M. Polloreno, Arnaud Carignan-Dugas, Jordan Hines, Robin Blume-Kohout, Kevin Young, and Timothy Proctor, Quantum 9, 1848 (2025). Randomized benchmarking (RB) protocols are widely used to measure an average error rate for a set of quantum logic gates. However, the standard version of RB is limited because it only bench…
Paper Constrained and Vanishing Expressivity of Quantum Fourier Models Hela Mhiri, Leo Monbroussou, Mario Herrero-Gonzalez, Slimane Thabet, Elham Kashefi, and Jonas Landman, Quantum 9, 1847 (2025). In this work, we highlight an unforeseen behavior of the expressivity of Parameterized Quantum Circuits (PQCs) for machine learning. A large class of these models, seen as Fourier series who…
Paper Efficient fault-tolerant code switching via one-way transversal CNOT gates Sascha Heußen and Janine Hilder, Quantum 9, 1846 (2025). Code switching is an established technique that facilitates a universal set of FT quantum gate operations by combining two QEC codes with complementary sets of gates, which each by themselve…
Paper The Dirac Vacuum in Discrete Spacetime Chaitanya Gupta and Anthony J. Short, Quantum 9, 1845 (2025). We consider introducing the Dirac sea in a quantum cellular automata model of fermions in discrete spacetime which approximates the Dirac equation in the continuum limit. However, if we atte…
Paper $su(d)$-squeezing and many-body entanglement geometry in finite-dimensional systems Giuseppe Vitagliano, Otfried Gühne, and Géza Tóth, Quantum 9, 1844 (2025). Generalizing the well-known spin-squeezing inequalities, we study the relation between squeezing of collective $N$-particle $su(d)$ operators and many-body entanglement geometry in multi-particl…
Paper Lindblad engineering for quantum Gibbs state preparation under the eigenstate thermalization hypothesis Eric Brunner, Luuk Coopmans, Gabriel Matos, Matthias Rosenkranz, Frederic Sauvage, and Yuta Kikuchi, Quantum 9, 1843 (2025). Building upon recent progress in Lindblad engineering for quantum Gibbs state preparation algorithms, we propose a simplified protocol that is shown to be efficient under the eigenstate ther…
Paper Targeted Clifford logical gates for hypergraph product codes Adway Patra and Alexander Barg, Quantum 9, 1842 (2025). Starting with an explicit framework for designing logical Clifford circuits for CSS codes, we construct logical gates for Hypergraph Product Codes. We first derive symplectic matrices for CN…
Paper Batched Line Search Strategy for Navigating through Barren Plateaus in Quantum Circuit Training Jakab Nádori, Gregory Morse, Barna Fülöp Villám, Zita Majnay-Takács, Zoltán Zimborás, and Péter Rakyta, Quantum 9, 1841 (2025). Variational quantum algorithms are viewed as promising candidates for demonstrating quantum advantage on near-term devices. These approaches typically involve the training of parameterized q…
Paper Reduced Sampling Overhead for Probabilistic Error Cancellation by Pauli Error Propagation Timon Scheiber, Paul Haubenwallner, and Matthias Heller, Quantum 9, 1840 (2025). Quantum error mitigation is regarded as a possible path to near-term quantum utility. The methods under the quantum error mitigation umbrella term, such as probabilistic error cancellation (…
Paper Superposition detection and QMA with non-collapsing measurements Roozbeh Bassirian and Kunal Marwaha, Quantum 9, 1839 (2025). We prove that $\sf{QMA}$ where the verifier may also make a single $non-collapsing$ measurement [7] is equal to $\sf{NEXP}$, resolving an open question of Aaronson [5]. We show this is a corollary…
Paper Preparing low-variance states using a distributed quantum algorithm Xiaoyu Liu, Benjamin F. Schiffer, and Jordi Tura, Quantum 9, 1838 (2025). Quantum computers are a highly promising tool for efficiently simulating quantum many-body systems. The preparation of their eigenstates is of particular interest and can be addressed, e.g.,…
Paper Minimal criteria for continuous-variable genuine multipartite entanglement Olga Leskovjanová and Ladislav Mišta Jr., Quantum 9, 1837 (2025). We derive a set of genuine multi-mode entanglement criteria for second moments of the quadrature operators. The criteria have a common form of the uncertainty relation between sums of varian…
Paper Estimating Eigenenergies from Quantum Dynamics: A Unified Noise-Resilient Measurement-Driven Approach Yizhi Shen, Daan Camps, Aaron Szasz, Siva Darbha, Katherine Klymko, David B. Williams–Young, Norm M. Tubman, and Roel Van Beeumen, Quantum 9, 1836 (2025). Ground state energy estimation in physical, chemical, and materials sciences is one of the most promising applications of quantum computing. In this work, we introduce a new hybrid approach…
Paper Estimating quantum Markov chains using coherent absorber post-processing and pattern counting estimator Federico Girotti, Alfred Godley, and Madalin Guta, Quantum 9, 1835 (2025). We propose a two step strategy for estimating one-dimensional dynamical parameters of a quantum Markov chain, which involves quantum post-processing the output using a coherent quantum absor…
Paper Parallel Quantum Signal Processing Via Polynomial Factorization John M. Martyn, Zane M. Rossi, Kevin Z. Cheng, Yuan Liu, and Isaac L. Chuang, Quantum 9, 1834 (2025). Quantum signal processing (QSP) is a methodology for constructing polynomial transformations of a linear operator encoded in a unitary. Applied to an encoding of a state $\rho$, QSP enables th…
Paper Riemannian quantum circuit optimization based on matrix product operators Isabel Nha Minh Le, Shuo Sun, and Christian B. Mendl, Quantum 9, 1833 (2025). We significantly enhance the simulation accuracy of initial Trotter circuits for Hamiltonian simulation of quantum systems by integrating first-order Riemannian optimization with tensor netw…
