New Techniques and Ideas in Quantum Measurement Theory and The 2nd International Symposium on Foundations of Quantum Mechanics in the Light of New Technology

Physics Today ◽  
1988 ◽  
Vol 41 (8) ◽  
pp. 71-71
Author(s):  
Daniel M. Greenberger ◽  
Mikio Namiki ◽  
Yoshio Ohnuki ◽  
Yoshimasa Murayama ◽  
Sadao Nomura ◽  
...  
Keyword(s):  
Quantum Mechanics ◽  
International Symposium ◽  
Quantum Measurement ◽  
New Technology ◽  
Measurement Theory ◽  
Foundations Of Quantum Mechanics ◽  
Quantum Measurement Theory ◽  
New Techniques

scholarly journals Does Decoherence Select the Pointer Basis of a Quantum Meter?

Entropy ◽  
2022 ◽  
Vol 24 (1) ◽  
pp. 106
Author(s):  
Abraham G. Kofman ◽  
Gershon Kurizki
Keyword(s):  
Quantum Mechanics ◽  
Quantum State ◽  
Quantum Measurement ◽  
Measurement Theory ◽  
Quantum Measurements ◽  
Quantum Measurement Theory ◽  
Measuring Device ◽  
Standard Quantum ◽  
Pointer States ◽  
Projective Measurements

The consensus regarding quantum measurements rests on two statements: (i) von Neumann’s standard quantum measurement theory leaves undetermined the basis in which observables are measured, and (ii) the environmental decoherence of the measuring device (the “meter”) unambiguously determines the measuring (“pointer”) basis. The latter statement means that the environment monitors (measures) selected observables of the meter and (indirectly) of the system. Equivalently, a measured quantum state must end up in one of the “pointer states” that persist in the presence of the environment. We find that, unless we restrict ourselves to projective measurements, decoherence does not necessarily determine the pointer basis of the meter. Namely, generalized measurements commonly allow the observer to choose from a multitude of alternative pointer bases that provide the same information on the observables, regardless of decoherence. By contrast, the measured observable does not depend on the pointer basis, whether in the presence or in the absence of decoherence. These results grant further support to our notion of Quantum Lamarckism, whereby the observer’s choices play an indispensable role in quantum mechanics.

scholarly journals Decoherence and its role in the modern measurement problem

2012 ◽  
Vol 370 (1975) ◽  
pp. 4576-4593 ◽  
Author(s):  
David Wallace
Keyword(s):  
Wave Function ◽  
Quantum Mechanics ◽  
Quantum Measurement ◽  
Measurement Problem ◽  
Scientific Practice ◽  
Measurement Theory ◽  
Quantum Measurements ◽  
Quantum Measurement Problem ◽  
Modern Physics ◽  
Conceptual Problems

Decoherence is widely felt to have something to do with the quantum measurement problem, but getting clear on just what is made difficult by the fact that the ‘measurement problem’, as traditionally presented in foundational and philosophical discussions, has become somewhat disconnected from the conceptual problems posed by real physics. This, in turn, is because quantum mechanics as discussed in textbooks and in foundational discussions has become somewhat removed from scientific practice, especially where the analysis of measurement is concerned. This paper has two goals: firstly (§§1–2), to present an account of how quantum measurements are actually dealt with in modern physics (hint: it does not involve a collapse of the wave function) and to state the measurement problem from the perspective of that account; and secondly (§§3–4), to clarify what role decoherence plays in modern measurement theory and what effect it has on the various strategies that have been proposed to solve the measurement problem.

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