Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

The Double Quantum Dot Feline Cousin of Schrödinger's Cat : An Experimental Test bed for a Discourse of Quantum Measurement Dichotomies

S. Bandyopadhyay

Published Dec 28, 1999• 0 citations
OpenAlex

Abstract

Intriguing dichotomies in quantum measurement theory involving the role of the obersever, objective reality, collapse of wavefunctions and actualization of a measurement outcome are cast into a patholigical gedanken experiment involving a single electron in a double quantum dot system coupled via a weak link.

Related papers

The Double Quantum Dot Feline Cousin of Schroedinger's Cat: An Experimental Testbed for a Discourse of Quantum Measurement Dichotomies

Supriyo Bandyopadhyay

Intriguing dichotomies in quantum measurement theory involving the role of the obersever, objective reality, collapse of wavefunctions and actualization of a measurement outcome are cast into a patholigical gedanken experiment involving a single electron in a double quantum dot system coupled via a weak link.

arXiv:quant-ph/9912112•Dec 27, 1999•0 citations

The Double Quantum Dot Feline Cousin of Schrödinger's Cat

Somshubhro Bandyopadhyay

•Dec 28, 1999•0 citations

Entanglement, decoherence, and measurement

Art Hobson

The fully entangled Schrodinger cat state obtained immediately upon measurement of a superposed two state quantum system by a detector is often said to paradoxically predict macroscopically different outcomes simultaneously. However, nonlocal interferometry experiments and their accompanying quantum theoretical analyses, testing momentum entangled photon pairs over the full range of phases, demonstrate that the cat state does not fit this description. This state instead represents two nonlocally coherent correlations between its subsystems. Even if the detector is a cat, this state is not paradoxical. Furthermore, standard quantum theory correctly predicts the experimentally observed nonparadoxical outcomes. Thus both quantum theory and quantum experiments show there is no Schrodinger cat paradox associated with measurement. This resolves the problem of definite outcomes and, with it, the measurement problem. Upon entanglement with a detector, superpositions collapse nonlocally and unitarily to one definite macroscopic outcome. No special collapse postulate is needed.

•Apr 10, 2019•1 citation

Schrödinger’s Cat and the Meaning of It All

Frank S. Levin

Abstract Chapter 15 deals with various unresolved issues, such as how measurements are to be described, whether they induce collapse of linear superpositions, and if so, what the result should be. Another is whether quantum mechanics applies to macroscopic measuring devices, and if not, why not. Some of these issues are addressed via the Schrödinger cat-in-the-box experiment, in particular whether the cat is ever half alive and half dead; analogs of the corresponding Schrödinger-cat state (not involving a cat) have been studied experimentally. For Schrödinger, it was ridiculous to apply quantum mechanics to macroscopic situations, nevertheless, it has been explored by many physicists. Whether measurements induce collapse and whether collapse arises in various formulations/interpretations of quantum mechanics is examined in the context of generic measuring instruments known as pointer devices. Various conclusions have been reached, though consensus has not, despite only one interpretation having been verified experimentally.

•Sep 21, 2017•0 citations

Quantum erasing the nature of reality: or, perhaps, the reality of nature?

Paul G. Kwiat, Berthold‐Georg Englert

Introduction WHY must I treat the measuring device classically? What will happen to me if I don't?! Eugene Wigner The quantum measurement problem – how does an apparently “classical” definite world arise out of the random world of quantum superpositions – was and continues to be one of the fundamental philosophical issues in quantum mechanics. What we mean by a classical world, for example, is one in which macroscopic objects are not in superposition states of being simultaneously in several locations at once, and cats are never in coherent superpositions of being alive and dead. This lack of coherence is actually a loss of the coherence that exists at the level of the isolated quanta, but somehow does not survive the transition to the classical level of measuring apparatus. Such incoherent states are known as mixed states. Therefore, to study the quantum–classical interface, or even to investigate whether such an interface exists at all other than in the minds of “classical sympathizers,” one should look carefully at mixed states, how they arise and how they behave. Here we describe a set of experiments, both real and gedanken , investigating the subtleties of quantum interference when mixed states are involved. We start by describing the well-known double-slit experiment, and the loss of interference when which-path information can be had.

Cambridge University Press eBooks•Apr 22, 2004•12 citations

Schrödinger’s cat problem: Measurement, decoherence, macroscopic superposition, and definite outcomes

Sachin .

Schrödinger’s cat condenses the quantum measurement problem into an amplification chain: a microscopic alternative becomes correlated with distinguishable records, while linear quantum dynamics retains the records in an entangled state. The problem is not a puzzle about an animal with incompatible predicates. It concerns the relation between unitary dynamics, reduced-state classicality, and observing a outcome. This article develops the cat problem from the density-operator description of measurement, deriving the role of partial tracing and environmental decoherence, and distinguishing a decohered improper mixture from a proper classical ensemble. It examines pointer-state selection, Lindblad dynamics, quantum Darwinism, and responses to the outcome problem: Everettian branching, consistent histories, Bohmian mechanics, and objective-collapse models. Experimental realizations in trapped ions, cavity quantum electrodynamics, and mechanical resonators demonstrate superpositions of distinguishable alternatives. Bosonic cat codes show that macroscopic-superposition structure can be engineered as an information resource. The article identifies four weaknesses: conflating diagonal reduced states with collapse; treating non-equivalent “cat-size” measures as interchangeable; insufficient treatment of environmental noise in collapse tests; and an underdeveloped connection between measurement theory and error-corrected bosonic architectures.

International Journal of Physics and Mathematics•Jul 1, 2025•0 citations
The fully entangled Schrodinger cat state obtained immediately upon measurement of a superposed two state quantum system by a detector is often said to paradoxically predict macroscopically different outcomes simultaneously. However, nonlocal interferometry experiments and their accompanying quantum theoretical analyses, testing momentum entangled photon pairs over the full range of phases, demonstrate that the cat state does not fit this description. This state instead represents two nonlocally coherent correlations between its subsystems. Even if the detector is a cat, this state is not paradoxical. Furthermore, standard quantum theory correctly predicts the experimentally observed nonparadoxical outcomes. Thus both quantum theory and quantum experiments show there is no Schrodinger cat paradox associated with measurement. This resolves the problem of definite outcomes and, with it, the measurement problem. Upon entanglement with a detector, superpositions collapse nonlocally and unitarily to one definite macroscopic outcome. No special collapse postulate is needed.
Abstract Chapter 15 deals with various unresolved issues, such as how measurements are to be described, whether they induce collapse of linear superpositions, and if so, what the result should be. Another is whether quantum mechanics applies to macroscopic measuring devices, and if not, why not. Some of these issues are addressed via the Schrödinger cat-in-the-box experiment, in particular whether the cat is ever half alive and half dead; analogs of the corresponding Schrödinger-cat state (not involving a cat) have been studied experimentally. For Schrödinger, it was ridiculous to apply quantum mechanics to macroscopic situations, nevertheless, it has been explored by many physicists. Whether measurements induce collapse and whether collapse arises in various formulations/interpretations of quantum mechanics is examined in the context of generic measuring instruments known as pointer devices. Various conclusions have been reached, though consensus has not, despite only one interpretation having been verified experimentally.
Introduction WHY must I treat the measuring device classically? What will happen to me if I don't?! Eugene Wigner The quantum measurement problem – how does an apparently “classical” definite world arise out of the random world of quantum superpositions – was and continues to be one of the fundamental philosophical issues in quantum mechanics. What we mean by a classical world, for example, is one in which macroscopic objects are not in superposition states of being simultaneously in several locations at once, and cats are never in coherent superpositions of being alive and dead. This lack of coherence is actually a loss of the coherence that exists at the level of the isolated quanta, but somehow does not survive the transition to the classical level of measuring apparatus. Such incoherent states are known as mixed states. Therefore, to study the quantum–classical interface, or even to investigate whether such an interface exists at all other than in the minds of “classical sympathizers,” one should look carefully at mixed states, how they arise and how they behave. Here we describe a set of experiments, both real and gedanken , investigating the subtleties of quantum interference when mixed states are involved. We start by describing the well-known double-slit experiment, and the loss of interference when which-path information can be had.
Schrödinger’s cat condenses the quantum measurement problem into an amplification chain: a microscopic alternative becomes correlated with distinguishable records, while linear quantum dynamics retains the records in an entangled state. The problem is not a puzzle about an animal with incompatible predicates. It concerns the relation between unitary dynamics, reduced-state classicality, and observing a outcome. This article develops the cat problem from the density-operator description of measurement, deriving the role of partial tracing and environmental decoherence, and distinguishing a decohered improper mixture from a proper classical ensemble. It examines pointer-state selection, Lindblad dynamics, quantum Darwinism, and responses to the outcome problem: Everettian branching, consistent histories, Bohmian mechanics, and objective-collapse models. Experimental realizations in trapped ions, cavity quantum electrodynamics, and mechanical resonators demonstrate superpositions of distinguishable alternatives. Bosonic cat codes show that macroscopic-superposition structure can be engineered as an information resource. The article identifies four weaknesses: conflating diagonal reduced states with collapse; treating non-equivalent “cat-size” measures as interchangeable; insufficient treatment of environmental noise in collapse tests; and an underdeveloped connection between measurement theory and error-corrected bosonic architectures.