Quantum

Paper

Decomposable coherence and quantum fluctuation relations

Erick Hinds Mingo and David Jennings,

Quantum 3, 202 (2019).

In Newtonian mechanics, any closed-system dynamics of a composite system in a microstate will leave all its individual subsystems in distinct microstates, however this fails dramatically in…

Paper

Duality in Quantum Quenches and Classical Approximation Algorithms: Pretty Good or Very Bad

Matthew B. Hastings,

Quantum 3, 201 (2019).

We consider classical and quantum algorithms which have a duality property: roughly, either the algorithm provides some nontrivial improvement over random or there exist many solutions which…

Paper

Phase diffusion and the small-noise approximation in linear amplifiers: Limitations and beyond

Andy Chia, Michal Hajdušek, Rosario Fazio, Leong-Chuan Kwek, and Vlatko Vedral,

Quantum 3, 200 (2019).

The phase of an optical field inside a linear amplifier is widely known to diffuse with a diffusion coefficient that is inversely proportional to the photon number. The same process occurs i…

Paper

Tensorization of the strong data processing inequality for quantum chi-square divergences

Yu Cao and Jianfeng Lu,

Quantum 3, 199 (2019).

It is well-known that any quantum channel $\mathcal{E}$ satisfies the data processing inequality (DPI), with respect to various divergences, e.g., quantum $\chi^2_{\kappa}$ divergences and q…

Paper

Maximal nonlocality from maximal entanglement and mutually unbiased bases, and self-testing of two-qutrit quantum systems

Jędrzej Kaniewski, Ivan Šupić, Jordi Tura, Flavio Baccari, Alexia Salavrakos, and Remigiusz Augusiak,

Quantum 3, 198 (2019).

Bell inequalities are an important tool in device-independent quantum information processing because their violation can serve as a certificate of relevant quantum properties. Probably the b…

Paper

Thermodynamic length in open quantum systems

Matteo Scandi and Martí Perarnau-Llobet,

Quantum 3, 197 (2019).

The dissipation generated during a quasistatic thermodynamic process can be characterised by introducing a metric on the space of Gibbs states, in such a way that minimally-dissipating proto…

Paper

Localizing and excluding quantum information; or, how to share a quantum secret in spacetime

Patrick Hayden and Alex May,

Quantum 3, 196 (2019).

When can quantum information be localized to each of a collection of spacetime regions, while also excluded from another collection of regions? We answer this question by defining and analyz…

Paper

Concepts of work in autonomous quantum heat engines

Wolfgang Niedenzu, Marcus Huber, and Erez Boukobza,

Quantum 3, 195 (2019).

One of the fundamental questions in quantum thermodynamics concerns the decomposition of energetic changes into heat and work. Contrary to classical engines, the entropy change of the piston…

Paper

Anomalous Weak Values Without Post-Selection

Alastair A. Abbott, Ralph Silva, Julian Wechs, Nicolas Brunner, and Cyril Branciard,

Quantum 3, 194 (2019).

A weak measurement performed on a pre- and post-selected quantum system can result in an average value that lies outside of the observable's spectrum. This effect, usually referred to as an…

Paper

Pilot-assisted intradyne reception for high-speed continuous-variable quantum key distribution with true local oscillator

Fabian Laudenbach, Bernhard Schrenk, Christoph Pacher, Michael Hentschel, Chi-Hang Fred Fung, Fotini Karinou, Andreas Poppe, Momtchil Peev, and Hannes Hübel,

Quantum 3, 193 (2019).

We present a pilot-assisted coherent intradyne reception methodology for CV-QKD with true local oscillator. An optically phase-locked reference tone, prepared using carrier-suppressed optica…

Paper

Open quantum systems are harder to track than open classical systems

Prahlad Warszawski and Howard M. Wiseman,

Quantum 3, 192 (2019).

For a Markovian (in the strongest sense) open quantum system it is possible, by continuously monitoring the environment, to perfectly track the system; that is, to know the stochastically ev…

Paper

Theory of variational quantum simulation

Xiao Yuan, Suguru Endo, Qi Zhao, Ying Li, and Simon C. Benjamin,

Quantum 3, 191 (2019).

The variational method is a versatile tool for classical simulation of a variety of quantum systems. Great efforts have recently been devoted to its extension to quantum computing for effici…

Paper

Product Decomposition of Periodic Functions in Quantum Signal Processing

Jeongwan Haah,

Quantum 3, 190 (2019).

We consider an algorithm to approximate complex-valued periodic functions $f(e^{i\theta})$ as a matrix element of a product of $SU(2)$-valued functions, which underlies so-called quantum sig…

Paper

The complexity of simulating local measurements on quantum systems

Sevag Gharibian and Justin Yirka,

Quantum 3, 189 (2019).

An important task in quantum physics is the estimation of local quantities for ground states of local Hamiltonians. Recently, [Ambainis, CCC 2014] defined the complexity class ${P}^{{QMA}[{log}]}$…

Paper

Heat-Bath Algorithmic Cooling with optimal thermalization strategies

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

Quantum 3, 188 (2019).

Heat-Bath Algorithmic Cooling is a set of techniques for producing highly pure quantum systems by utilizing a surrounding heat-bath and unitary interactions. These techniques originally used…

Paper

Locally accurate MPS approximations for ground states of one-dimensional gapped local Hamiltonians

Alexander M. Dalzell and Fernando G. S. L. Brandão,

Quantum 3, 187 (2019).

A key feature of ground states of gapped local 1D Hamiltonians is their relatively low entanglement — they are well approximated by matrix product states (MPS) with bond dimension scaling…

Category: Paper