Alba Cervera-Lierta,

Quantum 2, 114 (2018).

We present an exact simulation of a one-dimensional transverse Ising spin chain with a quantum computer. We construct an efficient quantum circuit that diagonalizes the Ising Hamiltonian and…

Gael Sentís, Johannes N. Greiner, Jiangwei Shang, Jens Siewert, and Matthias Kleinmann,

Quantum 2, 113 (2018).

Preparing and certifying bound entangled states in the laboratory is an intrinsically hard task, due to both the fact that they typically form narrow regions in state space, and that a certi…

Raul Corrêa, Marina F. B. Cenni, and Pablo L. Saldanha,

Quantum 2, 112 (2018).

We show that a quantum particle subjected to a positive force in one path of a Mach-Zehnder interferometer and a null force in the other path may receive a negative average momentum transfer…

Frédéric Bouchard, Khabat Heshami, Duncan England, Robert Fickler, Robert W. Boyd, Berthold-Georg Englert, Luis L. Sánchez-Soto, and Ebrahim Karimi,

Quantum 2, 111 (2018).

Quantum key distribution is on the verge of real world applications, where perfectly secure information can be distributed among multiple parties. Several quantum cryptographic protocols hav…

Francesco Albarelli, Matteo A. C. Rossi, Dario Tamascelli, and Marco G. Genoni,

Quantum 2, 110 (2018).

We study quantum frequency estimation for $N$ qubits subjected to independent Markovian noise, via strategies based on time-continuous monitoring of the environment. Both physical intuition an…

Gian Luca Giorgi and Roberta Zambrini,

Quantum 2, 109 (2018).

Quantum coherence and distributed correlations among subparties are often considered as separate, although operationally linked to each other, properties of a quantum state. Here, we propose…

Matteo Fadel and Jordi Tura,

Quantum 2, 107 (2018).

We show that spin systems with infinite-range interactions can violate at thermal equilibrium a multipartite Bell inequality, up to a finite critical temperature $T_c$. Our framework can be ap…

Davide Orsucci, Hans J. Briegel, and Vedran Dunjko,

Quantum 2, 105 (2018).

Markov chain methods are remarkably successful in computational physics, machine learning, and combinatorial optimization. The cost of such methods often reduces to the mixing time, i.e., th…

John H. Selby and Jamie Sikora,

Quantum 2, 103 (2018).

We discuss the possibility of creating money that is physically impossible to counterfeit. Of course, "physically impossible" is dependent on the theory that is a faithful description of nat…

Markus S. Kesselring, Fernando Pastawski, Jens Eisert, and Benjamin J. Brown,

Quantum 2, 101 (2018).

The color code is both an interesting example of an exactly solved topologically ordered phase of matter and also among the most promising candidate models to realize fault-tolerant quantum…

María García Díaz, Kun Fang, Xin Wang, Matteo Rosati, Michalis Skotiniotis, John Calsamiglia, and Andreas Winter,

Quantum 2, 100 (2018).

Coherent superposition is a key feature of quantum mechanics that underlies the advantage of quantum technologies over their classical counterparts. Recently, coherence has been recast as a…

Yuan Su and John Watrous,

Quantum 2, 98 (2018).

The $\textit{quantum strategy}$ (or $\textit{quantum combs}$) framework is a useful tool for reasoning about interactions among entities that process and exchange quantum information over the co…

A. González-Tudela and J. I. Cirac,

Quantum 2, 97 (2018).

Quantum emitters coupled to structured photonic reservoirs experience unconventional individual and collective dynamics emerging from the interplay between dimensionality and non-trivial pho…

T.J. Volkoff and K.B. Whaley,

Quantum 2, 96 (2018).

For both unitary and open qubit dynamics, we compare asymmetry monotone-based bounds on the minimal time required for an initial qubit state to evolve to a final qubit state from which it is…

Johannes Bausch and Elizabeth Crosson,

Quantum 2, 94 (2018).

Feynman's circuit-to-Hamiltonian construction connects quantum computation and ground states of many-body quantum systems. Kitaev applied this construction to demonstrate QMA-completeness of…

Rui Chao, Ben W. Reichardt, Chris Sutherland, and Thomas Vidick,

Quantum 2, 92 (2018).

Bell-inequality violations establish that two systems share some quantum entanglement. We give a simple test to certify that two systems share an asymptotically large amount of entanglement,…

Mikel Sanz, Witlef Wieczorek, Simon Gröblacher, and Enrique Solano,

Quantum 2, 91 (2018).

The dynamical Casimir effect is an intriguing phenomenon in which photons are generated from vacuum due to a non-adiabatic change in some boundary conditions. In particular, it connects the…

Gus Gutoski, Ansis Rosmanis, and Jamie Sikora,

Quantum 2, 89 (2018).

We introduce a definition of the fidelity function for multi-round quantum strategies, which we call the $\textit{strategy fidelity}$, that is a generalization of the fidelity function for qua…

Christina Knapp, Michael Beverland, Dmitry I. Pikulin, and Torsten Karzig,

Quantum 2, 88 (2018).

Majorana-based quantum computing seeks to use the non-local nature of Majorana zero modes to store and manipulate quantum information in a topologically protected way. While noise is anticip…

Benjamin Dive, Alexander Pitchford, Florian Mintert, and Daniel Burgarth,

Quantum 2, 80 (2018).

Quantum simulators, machines that can replicate the dynamics of quantum systems, are being built as useful devices and are seen as a stepping stone to universal quantum computers. A key diff…

Adam Winick, Norbert Lütkenhaus, and Patrick J. Coles,

Quantum 2, 77 (2018).

In this work, we present a reliable, efficient, and tight numerical method for calculating key rates for finite-dimensional quantum key distribution (QKD) protocols. We illustrate our approa…

Felix A. Pollock and Kavan Modi,

Quantum 2, 76 (2018).

Memory effects in open quantum dynamics are often incorporated in the equation of motion through a superoperator known as the memory kernel, which encodes how past states affect future dynam…

Filippo M. Miatto, Michael Epping, and Norbert Lütkenhaus,

Quantum 2, 75 (2018).

Quantum information degrades over distance due to the unavoidable imperfections of the transmission channels, with loss as the leading factor. This simple fact hinders quantum communication,…

Armin Tavakoli, Géraldine Haack, Marcus Huber, Nicolas Brunner, and Jonatan Bohr Brask,

Quantum 2, 73 (2018).

We present a scheme for dissipatively generating maximal entanglement in a heralded manner. Our setup requires incoherent interactions with two thermal baths at different temperatures, but n…

Sophie Laplante, Mathieu Laurière, Alexandre Nolin, Jérémie Roland, and Gabriel Senno,

Quantum 2, 72 (2018).

The question of how large Bell inequality violations can be, for quantum distributions, has been the object of much work in the past several years. We say that a Bell inequality is normalize…

Kevin A. Fischer, Rahul Trivedi, Vinay Ramasesh, Irfan Siddiqi, and Jelena Vučković,

Quantum 2, 69 (2018).

We develop a new computational tool and framework for characterizing the scattering of photons by energy-nonconserving Hamiltonians into unidirectional (chiral) waveguides, for example, with…

Nikolas P. Breuckmann and Xiaotong Ni,

Quantum 2, 68 (2018).

Machine learning has the potential to become an important tool in quantum error correction as it allows the decoder to adapt to the error distribution of a quantum chip. An additional motiva…

Cédric Bény,

Quantum 2, 67 (2018).

Information-theoretical quantities such as statistical distinguishability typically result from optimisations over all conceivable observables. Physical theories, however, are not generally…

Mohammad Mehboudi, Anna Sanpera, and Juan M. R. Parrondo,

Quantum 2, 66 (2018).

The fluctuation-dissipation theorem (FDT) is a central result in statistical physics, both for classical and quantum systems. It establishes a relationship between the linear response of a s…

Dominik Hangleiter, Juan Bermejo-Vega, Martin Schwarz, and Jens Eisert,

Quantum 2, 65 (2018).

One of the main milestones in quantum information science is to realise quantum devices that exhibit an exponential computational advantage over classical ones without being universal quantu…

Christopher Eltschka and Jens Siewert,

Quantum 2, 64 (2018).

The physics of a many-particle system is determined by the correlations in its quantum state. Therefore, analyzing these correlations is the foremost task of many-body physics. Any 'a priori…

Sally Shrapnel and Fabio Costa,

Quantum 2, 63 (2018).

Realist interpretations of quantum mechanics presuppose the existence of elements of reality that are independent of the actions used to reveal them. Such a view is challenged by several no-…

Daniel Litinski and Felix von Oppen,

Quantum 2, 62 (2018).

We present a planar surface-code-based scheme for fault-tolerant quantum computation which eliminates the time overhead of single-qubit Clifford gates, and implements long-range multi-target…

Nicolai Friis and Marcus Huber,

Quantum 2, 61 (2018).

One of the most fundamental tasks in quantum thermodynamics is extracting energy from one system and subsequently storing this energy in an appropriate battery. Both of these steps, work ext…

Łukasz Rudnicki, Zbigniew Puchała, and Karol Zyczkowski,

Quantum 2, 60 (2018).

Motivated by the gate set tomography we study quantum channels from the perspective of information which is invariant with respect to the gauge realized through similarity of matrices repres…

René Schwonnek,

Quantum 2, 59 (2018).

We consider the uncertainty between two pairs of local projective measurements performed on a multipartite system. We show that the optimal bound in any linear uncertainty relation, formulat…

Earl T. Campbell and Mark Howard,

Quantum 2, 56 (2018).

Magic states are eigenstates of non-Pauli operators. One way of suppressing errors present in magic states is to perform parity measurements in their non-Pauli eigenbasis and postselect on e…

Alexander Müller-Hermes and Daniel Stilck Franca,

Quantum 2, 55 (2018).

We study the speed of convergence of a primitive quantum time evolution towards its fixed point in the distance of sandwiched Rényi divergences. For each of these distance measures the conve…

Christopher Chamberland and Michael E. Beverland,

Quantum 2, 53 (2018).

In this paper we introduce a general fault-tolerant quantum error correction protocol using flag circuits for measuring stabilizers of arbitrary distance codes. In addition to extending flag…

Matteo Lostaglio, Álvaro M. Alhambra, and Christopher Perry,

Quantum 2, 52 (2018).

To what extent do thermodynamic resource theories capture physically relevant constraints? Inspired by quantum computation, we define a set of elementary thermodynamic gates that only act on…

Damian S. Steiger, Thomas Häner, and Matthias Troyer,

Quantum 2, 49 (2018).

We introduce ProjectQ, an open source software effort for quantum computing. The first release features a compiler framework capable of targeting various types of hardware, a high-performanc…

Paul Baireuther, Thomas E. O’Brien, Brian Tarasinski, and Carlo W. J. Beenakker,

Quantum 2, 48 (2018).

A fault-tolerant quantum computation requires an efficient means to detect and correct errors that accumulate in encoded quantum information. In the context of machine learning, neural netwo…

Adam Stokes,

Quantum 2, 46 (2018).

The solution to the wave equation as a Cauchy problem with prescribed fields at an initial time $t=0$ is purely retarded. Similarly, in the quantum theory of radiation the specification of Hei…

Jordi Tura, Albert Aloy, Ruben Quesada, Maciej Lewenstein, and Anna Sanpera,

Quantum 2, 45 (2018).

We study the separability problem in mixtures of Dicke states i.e., the separability of the so-called Diagonal Symmetric (DS) states. First, we show that separability in the case of DS in…

Christopher Chamberland, Pavithran Iyer, and David Poulin,

Quantum 2, 43 (2018).

We consider the problem of fault-tolerant quantum computation in the presence of slow error diagnostics, either caused by measurement latencies or slow decoding algorithms. Our scheme offers…

Louis Villa and Gabriele De Chiara,

Quantum 2, 42 (2018).

We propose a method to experimentally measure the internal energy of a system of ultracold atoms trapped in optical lattices by coupling them to the fields of two optical cavities. We show t…