Quantum

Paper

Warm-starting quantum optimization

Daniel J. Egger, Jakub Mareček, and Stefan Woerner,

Quantum 5, 479 (2021).

There is an increasing interest in quantum algorithms for problems of integer programming and combinatorial optimization. Classical solvers for such problems employ relaxations, which replac…

Paper

Experimental localisation of quantum entanglement through monitored classical mediator

Soham Pal, Priya Batra, Tanjung Krisnanda, Tomasz Paterek, and T. S. Mahesh,

Quantum 5, 478 (2021).

Quantum entanglement is a form of correlation between quantum particles that cannot be increased via local operations and classical communication. It has therefore been proposed that an incr…

Paper

Optimal Multi-port-based Teleportation Schemes

Marek Mozrzymas, Michał Studziński, and Piotr Kopszak,

Quantum 5, 477 (2021).

In this paper, we introduce optimal versions of a multi-port based teleportation scheme allowing to send a large amount of quantum information. We fully characterise probabilistic and determ…

Paper

Quantum marginal problem and incompatibility

Erkka Haapasalo, Tristan Kraft, Nikolai Miklin, and Roope Uola,

Quantum 5, 476 (2021).

One of the basic distinctions between classical and quantum mechanics is the existence of fundamentally incompatible quantities. Such quantities are present on all levels of quantum objects:…

Paper

Quantum Physical Unclonable Functions: Possibilities and Impossibilities

Myrto Arapinis, Mahshid Delavar, Mina Doosti, and Elham Kashefi,

Quantum 5, 475 (2021).

A Physical Unclonable Function (PUF) is a device with unique behaviour that is hard to clone hence providing a secure fingerprint. A variety of PUF structures and PUF-based applications have…

Paper

Visualizing the emission of a single photon with frequency and time resolved spectroscopy

Aleksei Sharafiev, Mathieu L. Juan, Oscar Gargiulo, Maximilian Zanner, Stephanie Wögerer, Juan José García-Ripoll, and Gerhard Kirchmair,

Quantum 5, 474 (2021).

At the dawn of Quantum Physics, Wigner and Weisskopf obtained a full analytical description (a $\textit{photon portrait}$) of the emission of a single photon by a two-level system, using the b…

Paper

Variational quantum solver employing the PDS energy functional

Bo Peng and Karol Kowalski,

Quantum 5, 473 (2021).

Recently a new class of quantum algorithms that are based on the quantum computation of the connected moment expansion has been reported to find the ground and excited state energies. In par…

Paper

Certifying dimension of quantum systems by sequential projective measurements

Adel Sohbi, Damian Markham, Jaewan Kim, and Marco Túlio Quintino,

Quantum 5, 472 (2021).

This work analyzes correlations arising from quantum systems subject to sequential projective measurements to certify that the system in question has a quantum dimension greater than some $d$.…

Paper

Witnessing Wigner Negativity

Ulysse Chabaud, Pierre-Emmanuel Emeriau, and Frédéric Grosshans,

Quantum 5, 471 (2021).

Negativity of the Wigner function is arguably one of the most striking non-classical features of quantum states. Beyond its fundamental relevance, it is also a necessary resource for quantum…

Paper

The group structure of dynamical transformations between quantum reference frames

Angel Ballesteros, Flaminia Giacomini, and Giulia Gubitosi,

Quantum 5, 470 (2021).

Recently, it was shown that when reference frames are associated to quantum systems, the transformation laws between such quantum reference frames need to be modified to take into account th…

Paper

Efficient Bayesian phase estimation using mixed priors

Ewout van den Berg,

Quantum 5, 469 (2021).

We describe an efficient implementation of Bayesian quantum phase estimation in the presence of noise and multiple eigenstates. The main contribution of this work is the dynamic switching be…

Paper

$a\times b=c$ in $2+1$D TQFT

Matthew Buican, Linfeng Li, and Rajath Radhakrishnan,

Quantum 5, 468 (2021).

We study the implications of the anyon fusion equation $a\times b=c$ on global properties of $2+1$D topological quantum field theories (TQFTs). Here $a$ and $b$ are anyons that fuse together to give…

Paper

Efficient qubit phase estimation using adaptive measurements

Marco A. Rodríguez-García, Isaac Pérez Castillo, and P. Barberis-Blostein,

Quantum 5, 467 (2021).

Estimating correctly the quantum phase of a physical system is a central problem in quantum parameter estimation theory due to its wide range of applications from quantum metrology to crypto…

Paper

Analyzing the barren plateau phenomenon in training quantum neural networks with the ZX-calculus

Chen Zhao and Xiao-Shan Gao,

Quantum 5, 466 (2021).

In this paper, we propose a general scheme to analyze the gradient vanishing phenomenon, also known as the barren plateau phenomenon, in training quantum neural networks with the ZX-calculus…

Paper

Quantum advantage from energy measurements of many-body quantum systems

Leonardo Novo, Juani Bermejo-Vega, and Raúl García-Patrón,

Quantum 5, 465 (2021).

The problem of sampling outputs of quantum circuits has been proposed as a candidate for demonstrating a quantum computational advantage (sometimes referred to as quantum "supremacy"). In th…

Paper

Modeling and mitigation of cross-talk effects in readout noise with applications to the Quantum Approximate Optimization Algorithm

Filip B. Maciejewski, Flavio Baccari, Zoltán Zimborás, and Michał Oszmaniec,

Quantum 5, 464 (2021).

Measurement noise is one of the main sources of errors in currently available quantum devices based on superconducting qubits. At the same time, the complexity of its characterization and mi…

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