Paper Hitting statistics from quantum jumps A. Chia, T. Paterek, and L. C. Kwek, Quantum 1, 19 (2017). https://doi.org/10.22331/q-2017-07-21-19 We define the hitting time for a model of continuous-time open quantum walks in terms of quantum jumps. Our starting point is a master equation in Lindblad form, which can be taken as the qu…
Paper Decoupling with random diagonal unitaries Yoshifumi Nakata, Christoph Hirche, Ciara Morgan, and Andreas Winter, Quantum 1, 18 (2017). https://doi.org/10.22331/q-2017-07-21-18 We investigate decoupling, one of the most important primitives in quantum Shannon theory, by replacing the uniformly distributed random unitaries commonly used to achieve the protocol, with…
Paper Entanglement and squeezing in continuous-variable systems Manuel Gessner, Luca Pezzè, and Augusto Smerzi, Quantum 1, 17 (2017). https://doi.org/10.22331/q-2017-07-14-17 We introduce a multi-mode squeezing coefficient to characterize entanglement in $N$-partite continuous-variable systems. The coefficient relates to the squeezing of collective observables in…
Paper QCMA hardness of ground space connectivity for commuting Hamiltonians David Gosset, Jenish C. Mehta, and Thomas Vidick, Quantum 1, 16 (2017). https://doi.org/10.22331/q-2017-07-14-16 In this work we consider the ground space connectivity problem for commuting local Hamiltonians. The ground space connectivity problem asks whether it is possible to go from one (efficiently…
Paper Classification of all alternatives to the Born rule in terms of informational properties Thomas D. Galley and Lluis Masanes, Quantum 1, 15 (2017). https://doi.org/10.22331/q-2017-07-14-15 The standard postulates of quantum theory can be divided into two groups: the first one characterizes the structure and dynamics of pure states, while the second one specifies the structure…
Paper A largely self-contained and complete security proof for quantum key distribution Marco Tomamichel and Anthony Leverrier, Quantum 1, 14 (2017). https://doi.org/10.22331/q-2017-07-14-14 In this work we present a security analysis for quantum key distribution, establishing a rigorous tradeoff between various protocol and security parameters for a class of entanglement-based…
Paper A Stronger Theorem Against Macro-realism John-Mark A. Allen, Owen J. E. Maroney, and Stefano Gogioso, Quantum 1, 13 (2017). https://doi.org/10.22331/q-2017-07-14-13 Macro-realism is the position that certain macroscopic observables must always possess definite values: e.g. the table is in some definite position, even if we do not know what that is preci…
Paper Fast and high-fidelity entangling gate through parametrically modulated longitudinal coupling Baptiste Royer, Arne L. Grimsmo, Nicolas Didier, and Alexandre Blais, Quantum 1, 11 (2017). https://doi.org/10.22331/q-2017-05-11-11 We investigate an approach to universal quantum computation based on the modulation of longitudinal qubit-oscillator coupling. We show how to realize a controlled-phase gate by simultaneousl…
Paper A purification postulate for quantum mechanics with indefinite causal order Mateus Araújo, Adrien Feix, Miguel Navascués, and Časlav Brukner, Quantum 1, 10 (2017). https://doi.org/10.22331/q-2017-04-26-10 To study which are the most general causal structures which are compatible with local quantum mechanics, Oreshkov et al. introduced the notion of a process: a resource shared between some pa…
Paper Finite-density phase diagram of a $(1+1)-d$ non-abelian lattice gauge theory with tensor networks Pietro Silvi, Enrique Rico, Marcello Dalmonte, Ferdinand Tschirsich, and Simone Montangero, Quantum 1, 9 (2017). https://doi.org/10.22331/q-2017-04-25-9 We investigate the finite-density phase diagram of a non-abelian $SU(2)$ lattice gauge theory in $(1+1)$-dimensions using tensor network methods. We numerically characterise the phase diagra…
