scholarly journals Evidence for interactive common causes. Resuming the Cartwright-Hausman-Woodward debate

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Paul M. Näger
Keyword(s):  
Quantum Mechanics ◽  
Causal Model ◽  
Quantum Mechanical ◽  
Markov Condition ◽  
Causal Modelling ◽  
Mechanical Formalism ◽  
Common Causes ◽  
Quantum Mechanical Formalism ◽  
Causal Markov Condition ◽  
Quantum Phenomena

AbstractThe most serious candidates for common causes that fail to screen off (‘interactive common causes’, ICCs) and thus violate the causal Markov condition (CMC) refer to quantum phenomena. In her seminal debate with Hausman and Woodward, Cartwright early on focussed on unfortunate non-quantum examples. Especially, Hausman and Woodward’s redescriptions of quantum cases saving the CMC remain unchallenged. This paper takes up this lose end of the discussion and aims to resolve the debate in favour of Cartwright’s position. It systematically considers redescriptions of ICC structures, including those by Hausman and Woodward, and explains why these are inappropriate, when quantum mechanics (in an objective collapse interpretation) is true. It first shows that all cases of purported quantum ICCs are cases of entanglement and then, using the tools of causal modelling, it provides an analysis of the quantum mechanical formalism for the case that the collapse of entangled systems is best described as a causal model with an ICC.

scholarly journals On the role of entanglement in Schrödinger’s cat paradox

Open Physics ◽  
2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Stefan Rinner ◽  
Ernst Werner
Keyword(s):  
Radioactive Substance ◽  
The State ◽  
Entangled States ◽  
Quantum Mechanical ◽  
The Core ◽  
Mechanical Formalism ◽  
Quantum Mechanical Formalism ◽  
Cat States ◽  
Quantum Optical

AbstractIn this paper we re-investigate the core of Schrödinger’s “cat paradox”. We argue that one has to distinguish clearly between superpositions of macroscopic cat states |☺〉 + |☹〉 and superpositions of entangled states |☺, ↑〉 + |☹, ↓〉 which comprise both the state of the cat (☺=alive, ☹=dead) and the radioactive substance (↑=not decayed, ↓=decayed). It is shown, that in the case of the cat experiment recourse to decoherence or other mechanisms is not necessary in order to explain the absence of macroscopic superpositions. Additionally, we present modified versions of two quantum optical experiments as experimenta crucis. Applied rigorously, quantum mechanical formalism reduces the problem to a mere pseudo-paradox.

NILPOTENT QUANTUM MECHANICS

2010 ◽  
Vol 25 (05) ◽  
pp. 951-983 ◽  
Author(s):  
ANDRZEJ M. FRYDRYSZAK
Keyword(s):  
Hilbert Space ◽  
Quantum Mechanical ◽  
Level System ◽  
Natural Basis ◽  
Nonrelativistic Case ◽  
Mechanical Formalism ◽  
Generalized Schrödinger Equation ◽  
Qubit System ◽  
Natural Realization ◽  
Quantum Mechanical Formalism

We develop a generalized quantum mechanical formalism based on the nilpotent commuting variables (η-variables). In the nonrelativistic case such formalism provides natural realization of a two-level system (qubit). Using the space of η-wavefunctions, η-Hilbert space and generalized Schrödinger equation we study properties of pure multiqubit systems and also properties of some composed, hybrid models: fermion–qubit, boson–qubit. The fermion–qubit system can be truly supersymmetric, with both SUSY partners having identical spectra. It is a novel feature that SUSY transformations relate here only nilpotent object. The η-eigenfunctions of the Hamiltonian for the qubit–qubit system give the set of Bloch vectors as a natural basis.

5.—Mott Scattering and Stern-Gerlach Effect

1972 ◽  
Vol 71 (1) ◽  
pp. 51-59
Author(s):  
P. S. Farago
Keyword(s):  
Point Of View ◽  
Quantum Mechanical ◽  
Density Matrices ◽  
Standard Quantum ◽  
Type Experiment ◽  
Mechanical Formalism ◽  
Quantum Mechanical Formalism ◽  
Stokes Vectors ◽  
Mott Scattering

SynopsisIt is shown that, from an operational point of view, the production and detection of spin-polarised electrons by Mott scattering is equivalent to the performance of a Stern-Gerlach type experiment with heavy spin-one-half particles. The argument is based on standard quantum mechanical formalism using density matrices and Stokes vectors for the description of polarised assemblies of particles.

Stark broadening of the lines 4121 Å and 4437 Å of helium in a plasma: Quantum-mechanical calculations for the electron impact effects

1977 ◽  
Vol 55 (3) ◽  
pp. 240-242 ◽  
Author(s):  
J. M. Bassalo ◽  
M. Cattani
Keyword(s):  
Electron Impact ◽  
Experimental Results ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
Stark Broadening ◽  
Electron Collisions ◽  
Mechanical Formalism ◽  
Theoretical Predictions ◽  
Quantum Mechanical Formalism

We calculate the broadening and shift of two lines (4121 Å and 4437 Å) for neutral helium in a plasma. To obtain the effect of the electron collisions the quantum-mechanical formalism developed by Bassalo and Cattani is used. Our theoretical predictions are compared with the experimental results of Wulff and of Bötticher, Roder, and Wobig and with the semi-classical estimates of Griem, Baranger, Kolb, and Oertel.

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