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 […]
Peter Shor published one of the earliest algorithms for quantum computers in 1994. Running Shor’s algorithm on a hypothetical quantum computer, one could rapidly factor enormous numbers—a seemingly innocuous superpower. But because the security of […]
Quantum 8, 1441 (2024). https://doi.org/10.22331/q-2024-08-14-1441 Virtual distillation has been proposed as an error mitigation protocol for estimating the expectation values of observables in quantum algorithms. It proceeds by creating a cyclic permutation of $M$ noisy […]
Quantum 8, 1440 (2024). https://doi.org/10.22331/q-2024-08-14-1440 Since their first introduction, Quantum Reference Frame (QRF) transformations have been extensively discussed, generalising the covariance of physical laws to the quantum domain. Despite important progress, a formulation of QRF […]
Quantum 8, 1439 (2024). https://doi.org/10.22331/q-2024-08-14-1439 We discuss families of approximate quantum error correcting codes which arise as the nearly-degenerate ground states of certain quantum many-body Hamiltonians composed of non-commuting terms. For exact codes, the conditions […]
Quantum 8, 1438 (2024). https://doi.org/10.22331/q-2024-08-13-1438 The Krylov subspace methods, being one category of the most important classical numerical methods for linear algebra problems, can be much more powerful when generalised to quantum computing. However, quantum […]
Quantum 8, 1437 (2024). https://doi.org/10.22331/q-2024-08-13-1437 Assessment of practical quantum information processing (QIP) remains partial without understanding limits imposed by noise. Unfortunately, mere description of noise grows exponentially with system size, becoming cumbersome even for modest […]
Quantum 8, 1436 (2024). https://doi.org/10.22331/q-2024-08-12-1436 With the advent of quantum technology, the interest in communication tasks assisted by quantum systems has increased both in academia and industry. Nonetheless, the transmission of a quantum state in […]
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