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Many protocols require precise rotation measurement. Here we present a general class of states that surpass the shot noise limit for measuring rotation around arbitrary axes. We then derive a quantum Cram\'er-Rao bound for simultaneously…

Quantum Physics · Physics 2019-03-20 Aaron Z. Goldberg , Daniel F. V. James

One of the fundamental tenets of quantum mechanics is that non-orthogonal states cannot be distinguished perfectly. When distinguishing multiple copies of a mixed quantum state, a collective measurement, which generates entanglement between…

Quantum Physics · Physics 2025-04-02 Lorcan Conlon , Jin Ming Koh , Biveen Shajilal , Jasminder Sidhu , Ping Koy Lam , Syed M. Assad

Unsolved controversies about uncertainty relations and quantum measurements still persists nowadays. They originate around the shortcomings regarding the conventional interpretation of uncertainty relations. Here we show that the respective…

Quantum Physics · Physics 2007-05-23 S. Dumitru

In this paper, we show how the Robertson uncertainty relation gives certain intrinsic quantum limits of measurements in the most general and rigorous mathematical treatment. A general lower bound for the product of the root-mean-square…

Quantum Physics · Physics 2015-05-20 Masanao Ozawa

Gaussian distribution of a quantum state with continuous spectrum is known to maximize the Shannon entropy at a fixed variance. Applying it to a pair of canonically conjugate quantum observables $\hat x$ and $\hat p$, quantum entropic…

Quantum Physics · Physics 2015-07-21 Wonmin Son

Measurements of quantum states form a key component in quantum-information processing. It is therefore an important task to compare measurements and furthermore decide if a measurement strategy is optimal. Entropic quantities, such as the…

Quantum Physics · Physics 2023-05-17 Wilfred Salmon , Sergii Strelchuk , David Arvidsson-Shukur

Heisenberg's uncertainty principle, which imposes intrinsic restrictions on our ability to predict the outcomes of incompatible quantum measurements to arbitrary precision, demonstrates one of the key differences between classical and…

Quantum Physics · Physics 2021-05-05 Yunlong Xiao , Kuntal Sengupta , Siren Yang , Gilad Gour

In this short note we show how the Generalised Uncertainty Principle (GUP) and the Extended Uncertainty Principle (EUP), two of the most common generalised uncertainty relations proposed in the quantum gravity literature, can be derived…

General Relativity and Quantum Cosmology · Physics 2023-02-17 Matthew J. Lake , Marek Miller , Ray Ganardi , Tomasz Paterek

The optimal quantum measurements for estimating different unknown parameters in a parameterized quantum state are usually incompatible with each other. Traditional approaches to addressing the measurement incompatibility issue, such as the…

Quantum Physics · Physics 2026-02-03 Sisi Zhou , Senrui Chen

For linear combinations of quantum product averages in an arbitrary bipartite state, we derive new quantum Bell-form and CHSH-form inequalities with the right-hand sides expressed in terms of a bipartite state. This allows us to specify in…

Quantum Physics · Physics 2011-01-04 Elena R. Loubenets

We show that the quantum measurement known as the pretty good measurement can be used to identify an unknown quantum state picked from any set of $n$ mixed states that have pairwise fidelities upper-bounded by a constant below 1, given…

Quantum Physics · Physics 2019-11-11 Ashley Montanaro

General characterization of physical measurements is discussed within the framework of a classical information theory. Uncertainty relation for simultaneous measurements of two physical observables is defined in this framework for…

Quantum Physics · Physics 2012-12-18 Yoshimasa Kurihara

The theory of generalised measurements is used to examine the problem of discriminating unambiguously between non-orthogonal pure quantum states. Measurements of this type never give erroneous results, although, in general, there will be a…

Quantum Physics · Physics 2009-10-31 Anthony Chefles

We derive lower bounds on the variance of estimators in quantum metrology by choosing test observables that define constraints on the unbiasedness of the estimator. The quantum bounds are obtained by analytical optimization over all…

Quantum Physics · Physics 2023-07-27 M. Gessner , A. Smerzi

An analysis of quantum measurement is presented that relies on an information-theoretic description of quantum entanglement. In a consistent quantum information theory of entanglement, entropies (uncertainties) conditional on measurement…

Quantum Physics · Physics 2008-02-03 N. J. Cerf , C. Adami

Minimum-uncertainty squeezed states, related to a broad class of observables, are analyzed. Methods for characterizing such states are developed, which are based on numerical solutions of ordinary differential equations. As typical examples…

Quantum Physics · Physics 2007-12-24 E. Shchukin , W. Vogel , Th. Kiesel

The entropic uncertainty principle in the form proven by Maassen and Uffink yields a fundamental inequality that is prominently used in many places all over the field of quantum information theory. In this work, we provide a family of…

Quantum Physics · Physics 2023-03-22 Antonio F. Rotundo , René Schwonnek

A geometric framework for quantum statistical estimation is used to establish a series of higher order corrections to the Heisenberg uncertainty relations associated with pairs of canonically conjugate variables. These corrections can be…

Quantum Physics · Physics 2007-05-23 Dorje C. Brody , Lane P. Hughston

By invoking quantum estimation theory we formulate bounds of errors in quantum measurement for arbitrary quantum states and observables in a finite-dimensional Hilbert space. We prove that the measurement errors of two observables satisfy…

Quantum Physics · Physics 2013-05-29 Yu Watanabe , Takahiro Sagawa , Masahito Ueda

We study the consequences of the generalized Heisenberg uncertainty relation which admits a minimal uncertainty in length such as the case in a theory of quantum gravity. In particular, the theory of quantum harmonic oscillators arising…

Quantum Physics · Physics 2015-06-26 P. Narayana Swamy