Quantum

Paper

Analysing causal structures in generalised probabilistic theories

Mirjam Weilenmann and Roger Colbeck,

Quantum 4, 236 (2020).

Causal structures give us a way to understand the origin of observed correlations. These were developed for classical scenarios, but quantum mechanical experiments necessitate their generali…

Paper

Compilation by stochastic Hamiltonian sparsification

Yingkai Ouyang, David R. White, and Earl T. Campbell,

Quantum 4, 235 (2020).

Simulation of quantum chemistry is expected to be a principal application of quantum computing. In quantum simulation, a complicated Hamiltonian describing the dynamics of a quantum system i…

Paper

Approximating Hamiltonian dynamics with the Nyström method

Alessandro Rudi, Leonard Wossnig, Carlo Ciliberto, Andrea Rocchetto, Massimiliano Pontil, and Simone Severini,

Quantum 4, 234 (2020).

Simulating the time-evolution of quantum mechanical systems is BQP-hard and expected to be one of the foremost applications of quantum computers. We consider classical algorithms for the app…

Paper

Extension of the Alberti-Ulhmann criterion beyond qubit dichotomies

Michele Dall’Arno, Francesco Buscemi, and Valerio Scarani,

Quantum 4, 233 (2020).

The Alberti-Ulhmann criterion states that any given qubit dichotomy can be transformed into any other given qubit dichotomy by a quantum channel if and only if the testing region of the form…

Paper

Control of anomalous diffusion of a Bose polaron

Christos Charalambous, Miguel Ángel García-March, Gorka Muñoz-Gil, Przemysław Ryszard Grzybowski, and Maciej Lewenstein,

Quantum 4, 232 (2020).

We study the diffusive behavior of a Bose polaron immersed in a coherently coupled two-component Bose-Einstein Condensate (BEC). We assume a uniform, one-dimensional BEC. Polaron superdiffus…

Paper

By-passing fluctuation theorems

Paul Boes, Rodrigo Gallego, Nelly H. Y. Ng, Jens Eisert, and Henrik Wilming,

Quantum 4, 231 (2020).

Fluctuation theorems impose constraints on possible work extraction probabilities in thermodynamical processes. These constraints are stronger than the usual second law, which is concerned o…

Paper

Quantum SDP-Solvers: Better upper and lower bounds

Joran van Apeldoorn, András Gilyén, Sander Gribling, and Ronald de Wolf,

Quantum 4, 230 (2020).

Brandão and Svore [14] recently gave quantum algorithms for approximately solving semidefinite programs, which in some regimes are faster than the best-possible classical algorithms in terms…

Paper

Maximum $N$-body correlations do not in general imply genuine multipartite entanglement

Christopher Eltschka and Jens Siewert,

Quantum 4, 229 (2020).

The existence of correlations between the parts of a quantum system on the one hand, and entanglement between them on the other, are different properties. Yet, one intuitively would identify…

Paper

Computational universality of symmetry-protected topologically ordered cluster phases on 2D Archimedean lattices

Austin K. Daniel, Rafael N. Alexander, and Akimasa Miyake,

Quantum 4, 228 (2020).

What kinds of symmetry-protected topologically ordered (SPTO) ground states can be used for universal measurement-based quantum computation in a similar fashion to the 2D cluster state? 2D S…

Paper

Completely positive master equation for arbitrary driving and small level spacing

Evgeny Mozgunov and Daniel Lidar,

Quantum 4, 227 (2020).

Markovian master equations are a ubiquitous tool in the study of open quantum systems, but deriving them from first principles involves a series of compromises. On the one hand, the Redfield…

Paper

Data re-uploading for a universal quantum classifier

Adrián Pérez-Salinas, Alba Cervera-Lierta, Elies Gil-Fuster, and José I. Latorre,

Quantum 4, 226 (2020).

A single qubit provides sufficient computational capabilities to construct a universal quantum classifier when assisted with a classical subroutine. This fact may be surprising since a singl…

Paper

A change of perspective: switching quantum reference frames via a perspective-neutral framework

Augustin Vanrietvelde, Philipp A. Hoehn, Flaminia Giacomini, and Esteban Castro-Ruiz,

Quantum 4, 225 (2020).

Treating reference frames fundamentally as quantum systems is inevitable in quantum gravity and also in quantum foundations once considering laboratories as physical systems. Both fields the…

Paper

Quantized Three-Ion-Channel Neuron Model for Neural Action Potentials

Tasio Gonzalez-Raya, Enrique Solano, and Mikel Sanz,

Quantum 4, 224 (2020).

The Hodgkin-Huxley model describes the conduction of the nervous impulse through the axon, whose membrane's electric response can be described employing multiple connected electric circuits…

Paper

From estimation of quantum probabilities to simulation of quantum circuits

Hakop Pashayan, Stephen D. Bartlett, and David Gross,

Quantum 4, 223 (2020).

Investigating the classical simulability of quantum circuits provides a promising avenue towards understanding the computational power of quantum systems. Whether a class of quantum circuits…

Paper

Ideal Projective Measurements Have Infinite Resource Costs

Yelena Guryanova, Nicolai Friis, and Marcus Huber,

Quantum 4, 222 (2020).

We show that it is impossible to perform ideal projective measurements on quantum systems using finite resources. We identify three fundamental features of ideal projective measurements and…

Paper

Quantum algorithms and lower bounds for convex optimization

Shouvanik Chakrabarti, Andrew M. Childs, Tongyang Li, and Xiaodi Wu,

Quantum 4, 221 (2020).

While recent work suggests that quantum computers can speed up the solution of semidefinite programs, little is known about the quantum complexity of more general convex optimization. We pre…

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