Quantum

Paper

Security of quantum key distribution with intensity correlations

Víctor Zapatero, Álvaro Navarrete, Kiyoshi Tamaki, and Marcos Curty,

Quantum 5, 602 (2021).

The decoy-state method in quantum key distribution (QKD) is a popular technique to approximately achieve the performance of ideal single-photon sources by means of simpler and practical lase…

Paper

Tensor Monopoles in superconducting systems

H. Weisbrich, M. Bestler, and W. Belzig,

Quantum 5, 601 (2021).

Topology in general but also topological objects such as monopoles are a central concept in physics. They are prime examples for the intriguing physics of gauge theories and topological stat…

Paper

Physical Implementability of Linear Maps and Its Application in Error Mitigation

Jiaqing Jiang, Kun Wang, and Xin Wang,

Quantum 5, 600 (2021).

Completely positive and trace-preserving maps characterize physically implementable quantum operations. On the other hand, general linear maps, such as positive but not completely positive m…

Paper

Theory and experiment for resource-efficient joint weak-measurement

Aldo C. Martinez-Becerril, Gabriel Bussières, Davor Curic, Lambert Giner, Raphael A. Abrahao, and Jeff S. Lundeen,

Quantum 5, 599 (2021).

Incompatible observables underlie pillars of quantum physics such as contextuality and entanglement. The Heisenberg uncertainty principle is a fundamental limitation on the measurement of th…

Paper

Efficient Characterization of Quantum Evolutions via a Recommender System

Priya Batra, Anukriti Singh, and T. S. Mahesh,

Quantum 5, 598 (2021).

We demonstrate characterizing quantum evolutions via matrix factorization algorithm, a particular type of the recommender system (RS). A system undergoing a quantum evolution can be characte…

Paper

The Power of Adiabatic Quantum Computation with No Sign Problem

Matthew B. Hastings,

Quantum 5, 597 (2021).

We show a superpolynomial oracle separation between the power of adiabatic quantum computation with no sign problem and the power of classical computation.

Paper

A diagrammatic approach to variational quantum ansatz construction

Y. Herasymenko and T.E. O’Brien,

Quantum 5, 596 (2021).

Variational quantum eigensolvers (VQEs) are a promising class of quantum algorithms for preparing approximate ground states in near-term quantum devices. Minimizing the error in such an appr…

Paper

Almost-linear time decoding algorithm for topological codes

Nicolas Delfosse and Naomi H. Nickerson,

Quantum 5, 595 (2021).

In order to build a large scale quantum computer, one must be able to correct errors extremely fast. We design a fast decoding algorithm for topological codes to correct for Pauli errors and…

Paper

Non-Markovian wave-function collapse models are Bohmian-like theories in disguise

Antoine Tilloy and Howard M. Wiseman,

Quantum 5, 594 (2021).

Spontaneous collapse models and Bohmian mechanics are two different solutions to the measurement problem plaguing orthodox quantum mechanics. They have, a priori nothing in common. At a form…

Paper

Groups, Platonic solids and Bell inequalities

Katarzyna Bolonek-Lasoń and Piotr Kosiński,

Quantum 5, 593 (2021).

The construction of Bell inequalities based on Platonic and Archimedean solids (Quantum 4 (2020), 293) is generalized to the case of orbits generated by the action of some finite groups. A n…

Paper

Error mitigation with Clifford quantum-circuit data

Piotr Czarnik, Andrew Arrasmith, Patrick J. Coles, and Lukasz Cincio,

Quantum 5, 592 (2021).

Achieving near-term quantum advantage will require accurate estimation of quantum observables despite significant hardware noise. For this purpose, we propose a novel, scalable error-mitigat…

Paper

Tunable zero modes and quantum interferences in flat-band topological insulators

Juan Zurita, Charles Creffield, and Gloria Platero,

Quantum 5, 591 (2021).

We investigate the interplay between Aharonov-Bohm (AB) caging and topological protection in a family of quasi-one-dimensional topological insulators, which we term CSSH ladders. Hybrids of…

Paper

Quantum thermo-dynamical construction for driven open quantum systems

Roie Dann and Ronnie Kosloff,

Quantum 5, 590 (2021).

Quantum dynamics of driven open systems should be compatible with both quantum mechanic and thermodynamic principles. By formulating the thermodynamic principles in terms of a set of postula…

Paper

Entanglement marginal problems

Miguel Navascués, Flavio Baccari, and Antonio Acín,

Quantum 5, 589 (2021).

We consider the entanglement marginal problem, which consists of deciding whether a number of reduced density matrices are compatible with an overall separable quantum state. To tackle this…

Paper

General Probabilistic Theories with a Gleason-type Theorem

Victoria J Wright and Stefan Weigert,

Quantum 5, 588 (2021).

Gleason-type theorems for quantum theory allow one to recover the quantum state space by assuming that (i) states consistently assign probabilities to measurement outcomes and that (ii) ther…

Paper

Two new results about quantum exact learning

Srinivasan Arunachalam, Sourav Chakraborty, Troy Lee, Manaswi Paraashar, and Ronald de Wolf,

Quantum 5, 587 (2021).

We present two new results about exact learning by quantum computers. First, we show how to exactly learn a $k$-Fourier-sparse $n$-bit Boolean function from $O(k^{1.5}(\log k)^2)$ uniform quantum…

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