Paper Cellular automata in operational probabilistic theories Paolo Perinotti, Quantum 4, 294 (2020). The theory of cellular automata in operational probabilistic theories is developed. We start introducing the composition of infinitely many elementary systems, and then use this notion to de…
Paper The Platonic solids and fundamental tests of quantum mechanics Armin Tavakoli and Nicolas Gisin, Quantum 4, 293 (2020). The Platonic solids is the name traditionally given to the five regular convex polyhedra, namely the tetrahedron, the octahedron, the cube, the icosahedron and the dodecahedron. Perhaps stro…
Paper Squeezing metrology: a unified framework Lorenzo Maccone and Alberto Riccardi, Quantum 4, 292 (2020). Quantum metrology theory has up to now focused on the resolution gains obtainable thanks to the entanglement among $N$ probes. Typically, a quadratic gain in resolution is achievable, going fr…
Paper Option Pricing using Quantum Computers Nikitas Stamatopoulos, Daniel J. Egger, Yue Sun, Christa Zoufal, Raban Iten, Ning Shen, and Stefan Woerner, Quantum 4, 291 (2020). We present a methodology to price options and portfolios of options on a gate-based quantum computer using amplitude estimation, an algorithm which provides a quadratic speedup compared to c…
Paper Variational quantum state preparation via quantum data buses Viacheslav V. Kuzmin and Pietro Silvi, Quantum 4, 290 (2020). We propose a variational quantum algorithm to prepare ground states of 1D lattice quantum Hamiltonians specifically tailored for programmable quantum devices where interactions among qubits…
Paper Quantum Zeno Dynamics from General Quantum Operations Daniel Burgarth, Paolo Facchi, Hiromichi Nakazato, Saverio Pascazio, and Kazuya Yuasa, Quantum 4, 289 (2020). We consider the evolution of an arbitrary quantum dynamical semigroup of a finite-dimensional quantum system under frequent kicks, where each kick is a generic quantum operation. We develop…
Paper Optimal probes and error-correction schemes in multi-parameter quantum metrology Wojciech Górecki, Sisi Zhou, Liang Jiang, and Rafał Demkowicz-Dobrzański, Quantum 4, 288 (2020). We derive a necessary and sufficient condition for the possibility of achieving the Heisenberg scaling in general adaptive multi-parameter estimation schemes in presence of Markovian noise.…
Paper Efficient Quantum Walk Circuits for Metropolis-Hastings Algorithm Jessica Lemieux, Bettina Heim, David Poulin, Krysta Svore, and Matthias Troyer, Quantum 4, 287 (2020). We present a detailed circuit implementation of Szegedy's quantization of the Metropolis-Hastings walk. This quantum walk is usually defined with respect to an oracle. We find that a direct…
Perspective Perspective on: Switching Quantum Reference Frames for Quantum Measurement Pierre Martin-Dussaud, Quantum Views 4, 40 (2020). Quantum reference frames In the last few years, the communities of quantum information and quantum gravity have been working together on the notion of $\textit{quantum reference frames}$. The…
Paper On the Entanglement Cost of One-Shot Compression Shima Bab Hadiashar and Ashwin Nayak, Quantum 4, 286 (2020). We revisit the task of visible compression of an ensemble of quantum states with entanglement assistance in the one-shot setting. The protocols achieving the best compression use many more q…
Paper Optimal Detection of Rotations about Unknown Axes by Coherent and Anticoherent States John Martin, Stefan Weigert, and Olivier Giraud, Quantum 4, 285 (2020). Coherent and anticoherent states of spin systems up to spin $j=2$ are known to be optimal in order to detect rotations by a known angle but unknown rotation axis. These optimal quantum rotosen…
Perspective What is non-classical about quantum no-cloning? Ana Belén Sainz, Quantum Views 4, 39 (2020). Contextuality Contextuality is one of the features of quantum theory that have no intuitive explanation. First identified by Bell back in 1964 [1], and later posed in more general terms by K…
Paper Quantum Codes of Maximal Distance and Highly Entangled Subspaces Felix Huber and Markus Grassl, Quantum 4, 284 (2020). We present new bounds on the existence of general quantum maximum distance separable codes (QMDS): the length $n$ of all QMDS codes with local dimension $D$ and distance $d \geq 3$ is bounded by…
Paper Switching Quantum Reference Frames for Quantum Measurement Jianhao M. Yang, Quantum 4, 283 (2020). Physical observation is made relative to a reference frame. A reference frame is essentially a quantum system given the universal validity of quantum mechanics. Thus, a quantum system must b…
Perspective Nonlocality strikes again Ivan Šupić, Quantum Views 4, 38 (2020). There is a certain type of papers whose value is that they are simple, yet very inspiring. There is no hard-core mathematical machinery behind, they rather witness a good intuition and under…
Paper A two-player dimension witness based on embezzlement, and an elementary proof of the non-closure of the set of quantum correlations Andrea Coladangelo, Quantum 4, 282 (2020). We describe a two-player non-local game, with a fixed small number of questions and answers, such that an $\epsilon$-close to optimal strategy requires an entangled state of dimension…
