Quantum 9, 1658 (2025). https://doi.org/10.22331/q-2025-03-10-1658 Parametrized quantum circuits (PQC) are quantum circuits which consist of both fixed and parametrized gates. In recent approaches to quantum machine learning (QML), PQCs are essentially ubiquitous and play the […]
Quantum 9, 1657 (2025). https://doi.org/10.22331/q-2025-03-10-1657 Computing key rates in quantum key distribution (QKD) numerically is essential to unlock more powerful protocols, that use more sophisticated measurement bases or quantum systems of higher dimension. It is […]
Quantum 9, 1656 (2025). https://doi.org/10.22331/q-2025-03-06-1656 We study the dynamics of an open quantum system linearly coupled to a bosonic reservoir. We show that, in the ultrastrong coupling limit, the system undergoes a nonselective measurement and […]
Quantum 9, 1655 (2025). https://doi.org/10.22331/q-2025-03-06-1655 The estimation of many-qubit observables is an essential task of quantum information processing. The generally applicable approach is to decompose the observables into weighted sums of multi-qubit Pauli strings, i.e., […]
Quantum 9, 1654 (2025). https://doi.org/10.22331/q-2025-03-06-1654 Device-independent (DI) quantum cryptography aims at providing secure cryptography with minimal trust in, or characterisation of, the underlying quantum devices. A key step in DI protocols is randomness extraction (or […]
Quantum 9, 1653 (2025). https://doi.org/10.22331/q-2025-03-05-1653 We consider an infinite-range interacting quantum spin-1/2 model, undergoing periodic kicking and dissipatively coupled with an environment. In the thermodynamic limit, it is described by classical mean-field equations that can […]
Quantum 9, 1652 (2025). https://doi.org/10.22331/q-2025-03-05-1652 We analyse two party non-local games whose predicate requires Alice and Bob to generate matching bits, and their three party extensions where a third player receives all inputs and is […]
Quantum 9, 1651 (2025). https://doi.org/10.22331/q-2025-02-26-1651 A key conjecture about the evolution of complex quantum systems towards an ergodic steady state, known as scrambling, is that this process acquires universal features when it is most efficient. […]
Quantum 9, 1650 (2025). https://doi.org/10.22331/q-2025-02-26-1650 The fascinating concept of coherent quantum absorber – which can absorb any photon emitted by another system while maintaining entanglement with that system – has found diverse implications in open […]
Quantum 9, 1649 (2025). https://doi.org/10.22331/q-2025-02-26-1649 The matrix rank and its positive versions are robust for small approximations, i.e. they do not decrease under small perturbations. In contrast, the multipartite tensor rank can collapse for arbitrarily […]
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