Quantum – the open journal for quantum science

Quantum has published 173 Papers in 3 Volumes, as well as 21 Views in Quantum Views.

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…

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…

Simulating lossy multiphoton linear optics experiments

Alex Neville,

Quantum Views 3, 19 (2019).

A significant research effort is being made to develop near-term quantum devices which fall short of fault-tolerance requirements and the ability to perform universal computation, but are ab…

Paper

Classification of phases for mixed states via fast dissipative evolution

Andrea Coser and David Pérez-García,

Quantum 3, 174 (2019).

We propose the following definition of topological quantum phases valid for mixed states: two states are in the same phase if there exists a time independent, fast and local Lindbladian evol…

Paper

A polar decomposition for quantum channels (with applications to bounding error propagation in quantum circuits)

Arnaud Carignan-Dugas, Matthew Alexander, and Joseph Emerson,

Quantum 3, 173 (2019).

Inevitably, assessing the overall performance of a quantum computer must rely on characterizing some of its elementary constituents and, from this information, formulate a broader statement…

Paper

The Non-m-Positive Dimension of a Positive Linear Map

Nathaniel Johnston, Benjamin Lovitz, and Daniel Puzzuoli,

Quantum 3, 172 (2019).

We introduce a property of a matrix-valued linear map $\Phi$ that we call its “non-m-positive dimension'' (or “non-mP dimension'' for short), which measures how large a subspace can be if…

Paper

Guaranteed recovery of quantum processes from few measurements

Martin Kliesch, Richard Kueng, Jens Eisert, and David Gross,

Quantum 3, 171 (2019).

Quantum process tomography is the task of reconstructing unknown quantum channels from measured data. In this work, we introduce compressed sensing-based methods that facilitate the reconstr…

Paper

Clifford recompilation for faster classical simulation of quantum circuits

Hammam Qassim, Joel J. Wallman, and Joseph Emerson,

Quantum 3, 170 (2019).

Simulating quantum circuits classically is an important area of research in quantum information, with applications in computational complexity and validation of quantum devices. One of the s…

Paper

Simulating boson sampling in lossy architectures

Raúl García-Patrón, Jelmer J. Renema, and Valery Shchesnovich,

Quantum 3, 169 (2019).

Photon losses are among the strongest imperfections affecting multi-photon interference. Despite their importance, little is known about their effect on boson sampling experiments. In this w…

Paper

Tight, robust, and feasible quantum speed limits for open dynamics

Francesco Campaioli, Felix A. Pollock, and Kavan Modi,

Quantum 3, 168 (2019).

Starting from a geometric perspective, we derive a quantum speed limit for arbitrary open quantum evolution, which could be Markovian or non-Markovian, providing a fundamental bound on the t…

Quantum adiabatic theory ventures into zeno dynamics

Martin Fraas,

Quantum Views 3, 18 (2019).

Quantum adiabatic theory has been developing through a productive interplay between applications in physics and formalisation in mathematics. It originated in the work of Born and Fock [1] o…

What can we learn from trivial measurements?

Marius Krumm,

Quantum Views 3, 17 (2019).

The discovery of quantum mechanics radically changed our understanding of the world. Today, trying to reveal the mysteries of quantum mechanics has become one of the most fruitful fields of…

The Page-Wootters mechanism 36 years on: a consistent formulation which accounts for interacting systems

Mischa Woods,

Quantum Views 3, 16 (2019).

Do we need dynamics to explain quantum systems which change over time? In closed systems, this is indeed the case — quantum systems evolve according to the Schrödinger equation in non-relati…

Paper

Applying quantum algorithms to constraint satisfaction problems

Earl Campbell, Ankur Khurana, and Ashley Montanaro,

Quantum 3, 167 (2019).

Quantum algorithms can deliver asymptotic speedups over their classical counterparts. However, there are few cases where a substantial quantum speedup has been worked out in detail for reaso…

Paper

Single-shot energetic-based estimator for entanglement in a half-parity measurement setup

Cyril Elouard, Alexia Auffèves, and Géraldine Haack,

Quantum 3, 166 (2019).

Producing and certifying entanglement between distant qubits is a highly desirable skill for quantum information technologies. Here we propose a new strategy to monitor and characterize enta…

Paper

Minimal energy cost of entanglement extraction

Lucas Hackl and Robert H. Jonsson,

Quantum 3, 165 (2019).

We compute the minimal energy cost for extracting entanglement from the ground state of a bosonic or fermionic quadratic system. Specifically, we find the minimal energy increase in the syst…