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Recall the classical hypothesis testing setting with two convex sets of probability distributions P and Q. One receives either n i.i.d. samples from a distribution p in P or from a distribution q in Q and wants to decide from which set the…

Information Theory · Computer Science 2020-07-20 Fernando G. S. L. Brandao , Aram W. Harrow , James R. Lee , Yuval Peres

A king in a directed graph is a node from which each node in the graph can be reached via paths of length at most two. There is a broad literature on tournaments (completely oriented digraphs), and it has been known for more than half a…

Computational Complexity · Computer Science 2007-05-23 Edith Hemaspaandra , Lane A. Hemaspaandra , Osamu Watanabe

Quantum state verification provides an efficient approach to characterize the reliability of quantum devices for generating certain target states. The figure of merit of a specific strategy is the estimated infidelity $\epsilon$ of the…

In this paper, we present a thought experiment that demonstrates that the equivalence of quantum reduced states and statistical mixed states of ensembles is not merely a simple mathematical formulation in quantum mechanics, but rather…

Quantum Physics · Physics 2025-04-18 Zhihong Zuo

Determining the state of a quantum system is a consuming procedure. For this reason, whenever one is interested only in some particular property of a state, it would be desirable to design a measurement setup that reveals this property with…

Quantum Physics · Physics 2017-06-02 Claudio Carmeli , Teiko Heinosaari , Jussi Schultz , Alessandro Toigo

Quantum theory encounters a difficulty when attempting to describe recording devices. If the recording is of events in which quantum uncertainty plays a role, such as an experiment on a quantum system, quantum theory is unable to correctly…

Quantum Physics · Physics 2026-02-10 Eric Tesse

This paper deals with maximization of classical $f$-divergence between the distributions of a measurement outputs of a given pair of quantum states. $f$-divergence $D_{f}$ between the probability density functions $p_{1}$ and $p_{2}$ over a…

Quantum Physics · Physics 2016-06-07 Keiji Matsumoto

We present the quantum measurement problem as a serious physics problem. Serious because without a resolution, quantum theory is not complete, as it does not tell how one should - in principle - perform measurements. It is physical in the…

Quantum Physics · Physics 2018-07-23 Nicolas Gisin

This work is a benchmark study for quantum-classical computing method with a real-world optimization problem from industry. The problem involves scheduling and balancing jobs on different machines, with a non-linear objective function. We…

Quantum Physics · Physics 2024-08-06 Abhishek Awasthi , Nico Kraus , Florian Krellner , David Zambrano

We derive a new lower bound on the success probability of the Pretty Good Measurement (PGM) for worst-case quantum state discrimination among $m$ pure states. Our bound is strictly tighter than the previously known Gram-matrix-based bound…

Quantum Physics · Physics 2026-02-27 Sergio Escobar , Austin Pechan

Quantum measurements are not deterministic. For this reason quantum measurements are repeated for a number of shots on identically prepared systems. The uncertainty in each measurement depends on the number of shots and the expected outcome…

Quantum Physics · Physics 2025-03-12 Pieter Thijs Eendebak

We consider the task of distinguishing whether a quantum system is prepared in a state from one of several sets of quantum states. Assuming their convexity and stability under tensor product, we prove that the optimal error exponent for…

Quantum Physics · Physics 2025-11-18 Kun Fang , Masahito Hayashi

The performance of the quantum approximate optimization algorithm is evaluated by using three different measures: the probability of finding the ground state, the energy expectation value, and a ratio closely related to the approximation…

Quantum Physics · Physics 2020-06-08 Madita Willsch , Dennis Willsch , Fengping Jin , Hans De Raedt , Kristel Michielsen

A novel class of hybrid quantum-classical algorithms based on the variational approach have recently emerged from separate proposals addressing, for example, quantum chemistry and combinatorial problems. These algorithms provide an…

Quantum Physics · Physics 2017-01-09 Gian Giacomo Guerreschi , Mikhail Smelyanskiy

Measurement is a fundamental notion in the usual approximate quantum mechanics of measured subsystems. Probabilities are predicted for the outcomes of measurements. State vectors evolve unitarily in between measurements and by reduction of…

General Relativity and Quantum Cosmology · Physics 2014-01-14 James B. Hartle

Quantum measurements of physical quantities are usually described as ideal measurements. However, only a few measurements fulfil the conditions of ideal measurements. The aim of the present work is to describe real position measurements…

Quantum Physics · Physics 2019-01-17 Klaus Wick

For two non-communicating parties, quantum theory can give rise to probability distributions of outcomes that no local classical model can reproduce without communication. However, in the case of two-dimensional systems ($d=2$), it is known…

Quantum Physics · Physics 2025-09-29 Mani Zartab , Giulio Gasbarri , Gael Sentís , Ramon Muñoz-Tapia

Quantum process tomography, the task of estimating an unknown quantum channel, is a central problem in quantum information theory. A long-standing open question is to determine the optimal number of uses of an unknown channel required to…

Quantum Physics · Physics 2026-01-19 Antonio Anna Mele , Lennart Bittel

The initialization of a quantum system into a certain state is a crucial aspect of quantum information science. While a variety of measurement strategies have been developed to characterize how well the system is initialized, for a given…

We consider how the theory of optimal quantum measurements determines the maximum information available to the receiving party of a quantum key distribution (QKD) system employing linearly independent but non-orthogonal quantum states. Such…

Quantum Physics · Physics 2024-01-04 Isabella Cerutti , Petra F. Scudo