Quantum 8, 1391 (2024). https://doi.org/10.22331/q-2024-07-02-1391 This paper proves the polynomial equivalence of a broad class of definitions of quantum computational complexity. We study right-invariant metrics on the unitary group—often called `complexity geometries’ following the definition […]
Quantum 8, 1390 (2024). https://doi.org/10.22331/q-2024-06-27-1390 We investigate what can be concluded about a quantum system when sequential quantum measurements of its observable – a prominent example of the so-called quantum stochastic process – fulfill the […]
Quantum 8, 1389 (2024). https://doi.org/10.22331/q-2024-06-27-1389 We introduce a quantum algorithm to efficiently prepare states with a small energy variance at the target energy. We achieve it by filtering a product state at the given energy […]
Quantum 8, 1388 (2024). https://doi.org/10.22331/q-2024-06-27-1388 New generations of ultracold-atom experiments are continually raising the demand for efficient solutions to optimal control problems. Here, we apply Bayesian optimization to improve a state-preparation protocol recently implemented in […]
Quantum 8, 1387 (2024). https://doi.org/10.22331/q-2024-06-27-1387 Non-local quantum computation (NLQC) is a cheating strategy for position-verification schemes, and has appeared in the context of the AdS/CFT correspondence. Here, we connect NLQC to the wider context of […]
Quantum 8, 1386 (2024). https://doi.org/10.22331/q-2024-06-25-1386 Quantum coherence is a crucial prerequisite for quantum technologies. Therefore, the robust generation, as autonomous as possible, of quantum coherence remains the essential problem for developing this field. We consider […]
Quantum 8, 1385 (2024). https://doi.org/10.22331/q-2024-06-25-1385 Quantum neural networks (QNNs) use parameterized quantum circuits with data-dependent inputs and generate outputs through the evaluation of expectation values. Calculating these expectation values necessitates repeated circuit evaluations, thus introducing […]
Quantum 8, 1384 (2024). https://doi.org/10.22331/q-2024-06-25-1384 We address the problem of quantifying the information content of a source for an arbitrary information theory, where the information content is defined in terms of the asymptotic achievable compression […]
Quantum 8, 1383 (2024). https://doi.org/10.22331/q-2024-06-20-1383 In this paper, we present a quantum computational method to calculate the many-body Green’s function matrix in a spin orbital basis. We apply our approach to finite-sized fermionic Hubbard models […]
Quantum 8, 1382 (2024). https://doi.org/10.22331/q-2024-06-20-1382 Discrete-variable (DV) quantum key distribution (QKD) based on single-photon detectors and sources have been successfully deployed for long-range secure key distribution. On the other hand, continuous-variable (CV) quantum key distribution […]
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