Paper Quantum violations in the Instrumental scenario and their relations to the Bell scenario Thomas Van Himbeeck, Jonatan Bohr Brask, Stefano Pironio, Ravishankar Ramanathan, Ana Belén Sainz, and Elie Wolfe, Quantum 3, 186 (2019). The causal structure of any experiment implies restrictions on the observable correlations between measurement outcomes, which are different for experiments exploiting classical, quantum, or…
Paper Two-Qubit Pure Entanglement as Optimal Social Welfare Resource in Bayesian Game Manik Banik, Some Sankar Bhattacharya, Nirman Ganguly, Tamal Guha, Amit Mukherjee, Ashutosh Rai, and Arup Roy, Quantum 3, 185 (2019). Entanglement is of paramount importance in quantum information theory. Its supremacy over classical correlations has been demonstrated in a numerous information theoretic protocols. Here we…
Paper Beyond the Cabello-Severini-Winter framework: Making sense of contextuality without sharpness of measurements Ravi Kunjwal, Quantum 3, 184 (2019). We develop a hypergraph-theoretic framework for Spekkens contextuality applied to Kochen-Specker (KS) type scenarios that goes beyond the Cabello-Severini-Winter (CSW) framework. To do this,…
Paper Quantum error correction for the toric code using deep reinforcement learning Philip Andreasson, Joel Johansson, Simon Liljestrand, and Mats Granath, Quantum 3, 183 (2019). We implement a quantum error correction algorithm for bit-flip errors on the topological toric code using deep reinforcement learning. An action-value Q-function encodes the discounted value…
Paper Faster quantum simulation by randomization Andrew M. Childs, Aaron Ostrander, and Yuan Su, Quantum 3, 182 (2019). Product formulas can be used to simulate Hamiltonian dynamics on a quantum computer by approximating the exponential of a sum of operators by a product of exponentials of the individual summ…
Paper Simulation of quantum circuits by low-rank stabilizer decompositions Sergey Bravyi, Dan Browne, Padraic Calpin, Earl Campbell, David Gosset, and Mark Howard, Quantum 3, 181 (2019). Recent work has explored using the stabilizer formalism to classically simulate quantum circuits containing a few non-Clifford gates. The computational cost of such methods is directly relat…
Perspective Deducing entanglement from signal fluctuations Alain Sarlette, Quantum Views 3, 23 (2019). The paper by Elouard et al, 2019 [1], considers the heralded entanglement between two qubits, from a continuous-time measurement that creates this entanglement. While the process is well-kno…
Perspective Quantum channels look simpler if you squint Jonas Helsen, Quantum Views 3, 22 (2019). One of the basic tools in any quantum information theorist is the completely positive trace preserving map, or quantum channel. They provide a general framework for discussing the dynamics a…
Paper Universal logical gates with constant overhead: instantaneous Dehn twists for hyperbolic quantum codes Ali Lavasani, Guanyu Zhu, and Maissam Barkeshli, Quantum 3, 180 (2019). A basic question in the theory of fault-tolerant quantum computation is to understand the fundamental resource costs for performing a universal logical set of gates on encoded qubits to arbi…
Paper Whenever a quantum environment emerges as a classical system, it behaves like a measuring apparatus Caterina Foti, Teiko Heinosaari, Sabrina Maniscalco, and Paola Verrucchi, Quantum 3, 179 (2019). We study the dynamics of a quantum system $\Gamma$ with an environment $\Xi$ made of $N$ elementary quantum components. We aim at answering the following questions: can the evolution of $\Gamma$…
Paper Quantum correlations for anonymous metrology A. J. Paige, Benjamin Yadin, and M. S. Kim, Quantum 3, 178 (2019). We introduce the task of anonymous metrology, in which a physical parameter of an object may be determined without revealing the object's location. Alice and Bob share a correlated quantum s…
Paper The maximum efficiency of nano heat engines depends on more than temperature Mischa P. Woods, Nelly Huei Ying Ng, and Stephanie Wehner, Quantum 3, 177 (2019). Sadi Carnot's theorem regarding the maximum efficiency of heat engines is considered to be of fundamental importance in thermodynamics. This theorem famously states that the maximum efficien…
Paper Semi-device-independent certification of indefinite causal order Jessica Bavaresco, Mateus Araújo, Časlav Brukner, and Marco Túlio Quintino, Quantum 3, 176 (2019). When transforming pairs of independent quantum operations according to the fundamental rules of quantum theory, an intriguing phenomenon emerges: some such higher-order operations may act on…
Paper Conditional work statistics of quantum measurements M. Hamed Mohammady and Alessandro Romito, Quantum 3, 175 (2019). In this paper we introduce a definition for conditional energy changes due to general quantum measurements, as the change in the conditional energy evaluated before, and after, the measureme…
Perspective Framework for Hamiltonian simulation and beyond: standard-form encoding, qubitization, and quantum signal processing Yuan Su, Quantum Views 3, 21 (2019). Simulating the Hamiltonian dynamics of a quantum system is one of the most promising applications of quantum computers. Indeed, the idea of quantum computers, suggested by Feynman [1] and Ma…
Perspective Quantum refrigerators – the quantum thermodynamics of cooling Bose gases Sebastian Deffner, Quantum Views 3, 20 (2019). We are living in exciting times. All around the globe national as well as international entities have founded "quantum initiatives", whose goal is the development of practical and commercial…
