Quantum 6, 752 (2022). https://doi.org/10.22331/q-2022-06-30-752 Quantum finite automata (QFA) are basic computational devices that make binary decisions using quantum operations. They are known to be exponentially memory efficient compared to their classical counterparts. Here, we […]
Quantum 6, 751 (2022). https://doi.org/10.22331/q-2022-06-29-751 We investigate whether certain non-classical communication channels can be simulated by a classical channel with a given number of states and a given `amount’ of noise. It is proved that […]
Quantum 6, 750 (2022). https://doi.org/10.22331/q-2022-06-29-750 We consider a collision between a moving particle and a fixed system, each having internal degrees of freedom. We identify the regime where the motion of the particle acts as […]
Quantum 6, 749 (2022). https://doi.org/10.22331/q-2022-06-29-749 We initiate the study of tradeoffs between exploration and exploitation in online learning of properties of quantum states. Given sequential oracle access to an unknown quantum state, in each round, […]
Quantum 6, 748 (2022). https://doi.org/10.22331/q-2022-06-29-748 We consider quantum systems with causal dynamics in discrete spacetimes, also known as quantum cellular automata (QCA). Due to time-discreteness this type of dynamics is not characterized by a Hamiltonian […]
Quantum 6, 747 (2022). https://doi.org/10.22331/q-2022-06-28-747 Quantum control has been of increasing interest in recent years, e.g. for tasks like state initialization and stabilization. Feedback-based strategies are particularly powerful, but also hard to find, due to […]
Quantum 6, 745 (2022). https://doi.org/10.22331/q-2022-06-27-745 We design and analyze two new low depth algorithms for amplitude estimation (AE) achieving an optimal tradeoff between the quantum speedup and circuit depth. For $beta in (0,1]$, our algorithms […]
Quantum 6, 744 (2022). https://doi.org/10.22331/q-2022-06-27-744 Evolutions of local Hamiltonians in short times are expected to remain local and thus limited. In this paper, we validate this intuition by proving some limitations on short-time evolutions of […]
Quantum 6, 744 (2022). https://doi.org/10.22331/q-2022-06-23-744 Out-of-time-ordered correlators (OTOCs) have been extensively studied in recent years as a diagnostic of quantum information scrambling. In this paper, we study quantum information-theoretic aspects of the $regularized$ finite-temperature OTOC. […]
Quantum 6, 743 (2022). https://doi.org/10.22331/q-2022-06-23-743 We study the problem of estimating the temperature of Gaussian systems with feasible measurements, namely Gaussian and photo-detection-like measurements. For Gaussian measurements, we develop a general method to identify the […]
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