Quantum

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…

Paper

Nonadaptive fault-tolerant verification of quantum supremacy with noise

Theodoros Kapourniotis and Animesh Datta,

Quantum 3, 164 (2019).

Quantum samplers are believed capable of sampling efficiently from distributions that are classically hard to sample from. We consider a sampler inspired by the classical Ising model. It is…

Paper

Hamiltonian Simulation by Qubitization

Guang Hao Low and Isaac L. Chuang,

Quantum 3, 163 (2019).

We present the problem of approximating the time-evolution operator $e^{-i\hat{H}t}$ to error $\epsilon$, where the Hamiltonian $\hat{H}=(\langle G|\otimes\hat{\mathcal{I}})\hat{U}(|G\rangle\otimes\hat{\mathcal{I}})$…

Paper

Approximation Algorithms for Complex-Valued Ising Models on Bounded Degree Graphs

Ryan L. Mann and Michael J. Bremner,

Quantum 3, 162 (2019).

We study the problem of approximating the Ising model partition function with complex parameters on bounded degree graphs. We establish a deterministic polynomial-time approximation scheme f…

Paper

Fundamental limits on low-temperature quantum thermometry with finite resolution

Patrick P. Potts, Jonatan Bohr Brask, and Nicolas Brunner,

Quantum 3, 161 (2019).

While the ability to measure low temperatures accurately in quantum systems is important in a wide range of experiments, the possibilities and the fundamental limits of quantum thermometry a…

Paper

Quantizing time: Interacting clocks and systems

Alexander R. H. Smith and Mehdi Ahmadi,

Quantum 3, 160 (2019).

This article generalizes the conditional probability interpretation of time in which time evolution is realized through entanglement between a clock and a system of interest. This formalism…

Paper

Determining a local Hamiltonian from a single eigenstate

Xiao-Liang Qi and Daniel Ranard,

Quantum 3, 159 (2019).

We ask whether the knowledge of a single eigenstate of a local Hamiltonian is sufficient to uniquely determine the Hamiltonian. We present evidence that the answer is “yes" for generic loca…

Paper

Conjugates, Filters and Quantum Mechanics

Alexander Wilce,

Quantum 3, 158 (2019).

The Jordan structure of finite-dimensional quantum theory is derived, in a conspicuously easy way, from a few simple postulates concerning abstract probabilistic models (each defined by a se…

Paper

No-free-information principle in general probabilistic theories

Teiko Heinosaari, Leevi Leppäjärvi, and Martin Plávala,

Quantum 3, 157 (2019).

In quantum theory, the no-information-without-disturbance and no-free-information theorems express that those observables that do not disturb the measurement of another observable and those…

Paper

Variational Quantum Computation of Excited States

Oscar Higgott, Daochen Wang, and Stephen Brierley,

Quantum 3, 156 (2019).

The calculation of excited state energies of electronic structure Hamiltonians has many important applications, such as the calculation of optical spectra and reaction rates. While low-depth…

Paper

Quantized refrigerator for an atomic cloud

Wolfgang Niedenzu, Igor Mazets, Gershon Kurizki, and Fred Jendrzejewski,

Quantum 3, 155 (2019).

We propose to implement a quantized thermal machine based on a mixture of two atomic species. One atomic species implements the working medium and the other implements two (cold and hot) bat…

Paper

Quantum states cannot be transmitted efficiently classically

Ashley Montanaro,

Quantum 3, 154 (2019).

We show that any classical two-way communication protocol with shared randomness that can approximately simulate the result of applying an arbitrary measurement (held by one party) to a quan…

Paper

Imperfect Thermalizations Allow for Optimal Thermodynamic Processes

Elisa Bäumer, Martí Perarnau-Llobet, Philipp Kammerlander, Henrik Wilming, and Renato Renner,

Quantum 3, 153 (2019).

Optimal (reversible) processes in thermodynamics can be modelled as step-by-step processes, where the system is successively thermalized with respect to different Hamiltonians by an external…

Paper

Generalized Adiabatic Theorem and Strong-Coupling Limits

Daniel Burgarth, Paolo Facchi, Hiromichi Nakazato, Saverio Pascazio, and Kazuya Yuasa,

Quantum 3, 152 (2019).

We generalize Kato's adiabatic theorem to nonunitary dynamics with an isospectral generator. This enables us to unify two strong-coupling limits: one driven by fast oscillations under a Hami…

Paper

Asymptotics of quantum channels: conserved quantities, an adiabatic limit, and matrix product states

Victor V. Albert,

Quantum 3, 151 (2019).

This work derives an analytical formula for the asymptotic state—the quantum state resulting from an infinite number of applications of a general quantum channel on some initial state. For…

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