Paper Analysis of quantum Krylov algorithms with errors William Kirby, Quantum 8, 1457 (2024). This work provides a nonasymptotic error analysis of quantum Krylov algorithms based on real-time evolutions, subject to generic errors in the outputs of the quantum circuits. We prove upper…
Paper Unraveling the emergence of quantum state designs in systems with symmetry Naga Dileep Varikuti and Soumik Bandyopadhyay, Quantum 8, 1456 (2024). Quantum state designs, by enabling an efficient sampling of random quantum states, play a quintessential role in devising and benchmarking various quantum protocols with broad applications r…
Paper On the connection between least squares, regularization, and classical shadows Zhihui Zhu, Joseph M. Lukens, and Brian T. Kirby, Quantum 8, 1455 (2024). Classical shadows (CS) offer a resource-efficient means to estimate quantum observables, circumventing the need for exhaustive state tomography. Here, we clarify and explore the connection b…
Paper Tutorial: projector approach to master equations for open quantum systems C. Gonzalez-Ballestero, Quantum 8, 1454 (2024). Most quantum theorists are familiar with different ways of describing the effective quantum dynamics of a system coupled to external degrees of freedom, such as the Born-Markov master equati…
Paper GraphiQ: Quantum circuit design for photonic graph states Jie Lin, Benjamin MacLellan, Sobhan Ghanbari, Julie Belleville, Khuong Tran, Luc Robichaud, Roger G. Melko, Hoi-Kwong Lo, and Piotr Roztocki, Quantum 8, 1453 (2024). $\tt{GraphiQ}$ is a versatile open-source framework for designing photonic graph state generation schemes, with a particular emphasis on photon-emitter hybrid circuits. Built in Python, Graphi…
Paper Quantum multi-anomaly detection Santiago Llorens, Gael Sentís, and Ramon Muñoz-Tapia, Quantum 8, 1452 (2024). A source assumed to prepare a specified reference state sometimes prepares an anomalous one. We address the task of identifying these anomalous states in a series of $n$ preparations with $k$ an…
Paper Expanding the reach of quantum optimization with fermionic embeddings Andrew Zhao and Nicholas C. Rubin, Quantum 8, 1451 (2024). Quadratic programming over orthogonal matrices encompasses a broad class of hard optimization problems that do not have an efficient quantum representation. Such problems are instances of th…
Paper Fast erasure decoder for hypergraph product codes Nicholas Connolly, Vivien Londe, Anthony Leverrier, and Nicolas Delfosse, Quantum 8, 1450 (2024). We propose a decoder for the correction of erasures with hypergraph product codes, which form one of the most popular families of quantum LDPC codes. Our numerical simulations show that this…
Paper Hamiltonian simulation for low-energy states with optimal time dependence Alexander Zlokapa and Rolando D. Somma, Quantum 8, 1449 (2024). We consider the task of simulating time evolution under a Hamiltonian $H$ within its low-energy subspace. Assuming access to a block-encoding of $H':=(H-E)/\lambda$, for some $\lambda \gt 0$ and…
Paper Quantum computation from dynamic automorphism codes Margarita Davydova, Nathanan Tantivasadakarn, Shankar Balasubramanian, and David Aasen, Quantum 8, 1448 (2024). We propose a new model of quantum computation comprised of low-weight measurement sequences that simultaneously encode logical information, enable error correction, and apply logical gates.…
Paper Double or nothing: a Kolmogorov extension theorem for multitime (bi)probabilities in quantum mechanics Davide Lonigro, Fattah Sakuldee, Łukasz Cywiński, Dariusz Chruściński, and Piotr Szańkowski, Quantum 8, 1447 (2024). The multitime probability distributions obtained by repeatedly probing a quantum system via the measurement of an observable generally violate Kolmogorov's consistency property. Therefore, o…
Paper Quantum Chaos and Coherence: Random Parametric Quantum Channels Apollonas S. Matsoukas-Roubeas, Tomaž Prosen, and Adolfo del Campo, Quantum 8, 1446 (2024). The survival probability of an initial Coherent Gibbs State (CGS) is a natural extension of the Spectral Form Factor (SFF) to open quantum systems. To quantify the interplay between quantum…
Paper Device-independent lower bounds on the conditional von Neumann entropy Peter Brown, Hamza Fawzi, and Omar Fawzi, Quantum 8, 1445 (2024). The rates of several device-independent (DI) protocols, including quantum key-distribution (QKD) and randomness expansion (RE), can be computed via an optimization of the conditional von Neu…
Paper Taming Quantum Time Complexity Aleksandrs Belovs, Stacey Jeffery, and Duyal Yolcu, Quantum 8, 1444 (2024). Quantum query complexity has several nice properties with respect to composition. First, bounded-error quantum query algorithms can be composed without incurring log factors through error re…
Paper Classical-to-quantum non-signalling boxes Carolina Moreira Ferrera, Robin Simmons, James Purcell, Daniel Collins, and Sandu Popescu, Quantum 8, 1443 (2024). Here we introduce the concept of classical input – quantum output (C-Q) non-signalling boxes, a generalisation of the classical input – classical output (C-C) non-signalling boxes. We argue…
Paper Certification of quantum state functions under partial information Leonardo Zambrano, Donato Farina, Egle Pagliaro, Marcio M. Taddei, and Antonio Acin, Quantum 8, 1442 (2024). Convex functions of quantum states play a key role in quantum physics, with examples ranging from Bell inequalities to von Neumann entropy. However, in experimental scenarios, direct measure…
