Quantum 6, 679 (2022). https://doi.org/10.22331/q-2022-03-31-679 This work analyses the performance of quantum circuits and general processes to transform $k$ uses of an arbitrary unitary operation $U$ into another unitary operation $f(U)$. When the desired function […]
Quantum 6, 678 (2022). https://doi.org/10.22331/q-2022-03-30-678 We show how to apply the recursive quantum approximate optimization algorithm (RQAOA) to MAX-$k$-CUT, the problem of finding an approximate $k$-vertex coloring of a graph. We compare this proposal to […]
Quantum 6, 677 (2022). https://doi.org/10.22331/q-2022-03-30-677 Variational quantum algorithms are ubiquitous in applications of noisy intermediate-scale quantum computers. Due to the structure of conventional parametrized quantum gates, the evaluated functions typically are finite Fourier series of […]
Quantum 6, 676 (2022). https://doi.org/10.22331/q-2022-03-30-676 We propose a quantum representation of binary classification trees with binary features based on a probabilistic approach. By using the quantum computer as a processor for probability distributions, a probabilistic […]
Quantum 6, 675 (2022). https://doi.org/10.22331/q-2022-03-30-675 The three key elements of a quantum simulation are state preparation, time evolution, and measurement. While the complexity scaling of time evolution and measurements are well known, many state preparation […]
Quantum 6, 674 (2022). https://doi.org/10.22331/q-2022-03-30-674 We investigate the interaction of weak light fields with two-dimensional lattices of atoms with high lying atomic Rydberg states. This system features different interactions that act on disparate length scales, […]
Quantum 6, 673 (2022). https://doi.org/10.22331/q-2022-03-29-673 Non-causal correlations certify the lack of a definite causal order among localized space-time regions. In stark contrast to scenarios where a single region influences its own causal past, some processes […]
Quantum 6, 672 (2022). https://doi.org/10.22331/q-2022-03-22-672 Thermal machines exploit interactions with multiple heat baths to perform useful tasks, such as work production and refrigeration. In the quantum regime, tasks with no classical counterpart become possible. Here, […]
Quantum 6, 671 (2022). https://doi.org/10.22331/q-2022-03-22-671 How can a multipartite single-photon path-entangled state be certified efficiently by means of local measurements? We address this question by constructing an entanglement witness based on local photon detections preceded […]
Quantum strongly condemns the 2022 invasion of Ukraine, the loss of life and war crimes inflicted by Vladimir Putin’s forces. There are no words to express our sorrow and fears. Lego house with an Ukrainian flag, […]
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