Quantum 8, 1451 (2024). https://doi.org/10.22331/q-2024-08-28-1451 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 the little noncommutative Grothendieck […]
Quantum 8, 1450 (2024). https://doi.org/10.22331/q-2024-08-27-1450 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 […]
Quantum 8, 1449 (2024). https://doi.org/10.22331/q-2024-08-27-1449 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 $E […]
Quantum 8, 1448 (2024). https://doi.org/10.22331/q-2024-08-27-1448 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. These measurement sequences constitute a […]
Quantum 8, 1447 (2024). https://doi.org/10.22331/q-2024-08-27-1447 The multitime probability distributions obtained by repeatedly probing a quantum system via the measurement of an observable generally violate Kolmogorov’s consistency property. Therefore, one cannot interpret such distributions as the […]
Quantum 8, 1446 (2024). https://doi.org/10.22331/q-2024-08-27-1446 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 […]
Quantum 8, 1445 (2024). https://doi.org/10.22331/q-2024-08-27-1445 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 Neumann entropy over a particular […]
Quantum 8, 1444 (2024). https://doi.org/10.22331/q-2024-08-23-1444 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 reduction $exactness$. Second, through careful […]
Quantum 8, 1443 (2024). https://doi.org/10.22331/q-2024-08-22-1443 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 that studying […]
Quantum 8, 1442 (2024). https://doi.org/10.22331/q-2024-08-16-1442 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 measurements of these […]
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