Journal of Physics Conference Series

Measurements of observables replaced by “evaluations” in Quantum Theory

Giuseppe Nisticò, Angela Sestito

Published Jul 3, 2015• 0 citations

Abstract

In quantum physics there are circumstances where the direct measurement of particular observables encounters difficulties; in some of these cases, however, its value can be evaluated, i.e. it can be inferred by measuring another observable characterized by perfect correlation with the observable of interest. Though an evaluation is often interpreted as a measurement of the evaluated observable, we prove that the two concepts cannot be identified in quantum physics, because the identification yields contradictions. Then, we establish the conceptual status of evaluations in Quantum Theory and the role can be ascribed to them.

DOI: 10.1088/1742-6596/626/1/012049

Related papers

Measurements of Observables Replaced by "Detections" in Quantum Theory

Nisticò, Giuseppe, Angela Sestito

In Quantum Physics it is not always possible to directly perform the measurement of an obsevable; in some of these cases, however, its value can be {\sl detected}, i.e. it can be inferred by measuring {\sl another} observable characterized by perfect correlation with the observable of interest. Though a {\sl detection} is often interpreted as a {\sl measurement} of the detected observable, we prove that the two concepts cannot be identified in Quantum Physics. Furthermore, we establish what meaning and role can be ascribed to detections coherently with Quantum Theory.

arXiv:1406.2217Jun 9, 20140 citations

Quantum Theoretical Concepts of Measurement: Part I

James L Park

The overall purpose of this paper is to clarify the physical meaning and epistemological status of the term ‘measurement’ as used in quantum theory. After a review of the essential logical structure of quantum physics. Part I presents interpretive discussions contrasting the quantal concepts observable and ensemble with their classical ancestors along the lines of Margenau's latency theory. Against this background various popular ideas concerning the nature of quantum measurement are critically surveyed. The analysis reveals that, in addition to internal mathematical difficulties, all the so-called quantum theories of measurement are grounded in unjustifiable, classical presuppositions.

Philosophy of ScienceSep 1, 196836 citations

The Quantum Measurement Problem

Olímpia Lombardi

Abstract In rough terms, the quantum measurement problem is the problem of explaining how, when a system in a superposition state is measured, the pointer observable of the measuring apparatus is always found in a definite value. Although quantum mechanics involves several interpretative challenges, the measurement problem has been the main focus of the interest of physicists and philosophers working on the foundations of the theory: most interpretations were designed specifically to solve it. In this chapter, it is shown that the MHI offers a solution to the measurement problem for both ideal and non-ideal measurements, and that, in the non-ideal case, the interpretation distinguishes between reliable and non-reliable measurements. I have also explained how the MHI accounts for consecutive measurements. Finally, it is emphasized that the MHI approach provides a new, more physical understanding of the concept of quantum measurement.

Feb 19, 20260 citations

Quantum averages of weak values

Yakir Aharonov, Alonso Botero

We re-examine the status of the weak value of a quantum mechanical observable as an objective physical concept, addressing its physical interpretation and general domain of applicability. We show that the weak value can be regarded as a definite mechanical effect on a measuring probe specifically designed to minimize the back reaction on the measured system. We then present an interesting framework for general measurement conditions (where the back reaction on the system may not be negligible) in which the measurement outcomes can still be interpreted as quantum averages of weak values. We show that in the classical limit, there is a direct correspondence between quantum averages of weak values and posterior expectation values of classical dynamical properties according to the classical inference framework.

arXiv:quant-ph/0503225Physical Review ANov 23, 2005111 citations

The Measurement Problem Is the "Measurement" Problem

Arne Hansen, Stefan Wolf

The term "measurement" in quantum theory (as well as in other physical theories) is ambiguous: It is used to describe both an experience - e.g., an observation in an experiment - and an interaction with the system under scrutiny. If doing physics is regarded as a creative activity to develop a meaningful description of the world, then one has to carefully discriminate between the two notions: An observer's account of experience - consitutive to meaning - is hardly expressed exhaustively by the formal framework of an interaction within one particular theory. We develop a corresponding perspective onto central terms in quantum mechanics in general, and onto the measurement problem in particular.

arXiv:1810.04573Oct 10, 20182 citations

What Exists Before Measurement? — The Missing Pre-Measurement Description in the Copenhagen Interpretation

Atsushi Okamoto

The conceptual status of the quantum state prior to measurement remains one of the most fundamental unresolved issues in the interpretation of quantum mechanics. While the Copenhagen interpretation successfully explains how measurement produces definite outcomes, it provides no explicit conceptual category describing what should be regarded as existing before measurement. Our previous study focused on the conceptual status of measurement values and proposed that measurement grants accessibility to a potential observational candidate, thereby allowing an observed value to become operationally realized. The present work extends this perspective to a more fundamental question: the conceptual status of existence prior to measurement. Within the Intrinsic Observability Framework (IOF), we introduce potential observability as a conceptual category characterizing the pre-measurement domain. Here, observability does not refer to the standard quantum-mechanical notion of an observable represented by a Hermitian operator. Instead, it denotes the capacity of a pre-measurement structure to become an observed outcome through accessibility. In this framework, measurement is interpreted as the act that grants accessibility to one potential observational candidate, thereby establishing observability. From this viewpoint, the quantum state prior to measurement is understood neither as a collection of already existing observable values nor as an undefined probabilistic entity. Rather, it represents a structured domain of potential observability that provides the conceptual basis from which observed reality subsequently emerges. The present work therefore does not reject the Copenhagen interpretation. Instead, it proposes a conceptual extension that explicitly characterizes the previously unspecified pre-measurement domain. By distinguishing measurement values from existence and clarifying the role of potential observability, this study provides a more coherent conceptual foundation for understanding quantum states, measurement, and observed reality.

Jul 18, 20260 citations