Tag: quantumjournal

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, […]

Quantum 6, 670 (2022). https://doi.org/10.22331/q-2022-03-17-670 We propose to perform amplitude estimation with the help of constant-depth quantum circuits that variationally approximate states during amplitude amplification. In the context of Monte Carlo (MC) integration, we numerically […]

Quantum 6, 669 (2022). https://doi.org/10.22331/q-2022-03-17-669 We propose a quantum repeater architecture that can operate under ambient conditions. Our proposal builds on recent progress towards non-cryogenic spin-photon interfaces based on nitrogen-vacancy centers, which have excellent spin […]

Quantum 6, 668 (2022). https://doi.org/10.22331/q-2022-03-17-668 Valiant-Vazirani showed in 1985 [45] that solving NP with the promise that “yes” instances have only one witness is powerful enough to solve the entire NP class (under randomized reductions). […]

Quantum 6, 667 (2022). https://doi.org/10.22331/q-2022-03-11-667 Quantum error correcting codes (QECCs) are the means of choice whenever quantum systems suffer errors, e.g., due to imperfect devices, environments, or faulty channels. By now, a plethora of families […]

Quantum 6, 666 (2022). https://doi.org/10.22331/q-2022-03-11-666 In this paper we describe an algebraic/geometrical approach to quantum scrambling. Generalized quantum subsystems are described by an hermitian-closed unital subalgebra $cal A$ of operators evolving through a unitary channel. […]

Quantum 6, 665 (2022). https://doi.org/10.22331/q-2022-03-10-665 Multiparameter quantum estimation is made difficult by the following three obstacles. First, incompatibility among different physical quantities poses a limit on the attainable precision. Second, the ultimate precision is not […]

Quantum 6, 664 (2022). https://doi.org/10.22331/q-2022-03-03-664 This article proposes the first discrete-time implementation of Rydberg quantum walk in multi-dimensional spatial space that could ideally simulate different classes of topological insulators. Using distance-selective exchange-interaction between Rydberg excited […]

Quantum 6, 663 (2022). https://doi.org/10.22331/q-2022-03-01-663 The causal order of events need not be fixed: whether a bus arrives before or after another at a certain stop can depend on other variables – like traffic. Coherent […]

Quantum 6, 662 (2022). https://doi.org/10.22331/q-2022-03-01-662 For a classical channel, neither the Shannon ca-pa-city, nor the sum of conditional probabilities corresponding to the cases of successful transmission can be increased by the use of shared entanglement, […]