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

Physical Review Letters

DNA Molecular Cousin of Schrödinger's Cat: A Curious Example of Quantum Measurement

Dipankar Home, Rajagopal Chattopadhyaya

Published Apr 15, 1996• 29 citations
Publisher

Abstract

It is argued that ultraviolet absorption by a DNA molecule (which gets biochemically attached to nearby photolyase enzyme so that the effect of uv absorption becomes macroscopically discernible) constitutes an intriguing example of quantum measurement. We point out that this does not merely illustrate the quantum measurement paradox in the hitherto unexplored arena of biological macromolecules, but is also instructive in highlighting specific difficulties inherent in various approaches to the measurement problem.

DOI
10.1103/physrevlett.76.2836

Related papers

Comment on “DNA Molecular Cousin of Schrödinger's Cat: A Curious Example of Quantum Measurement”

Asoke Prasun Chattopadhyay, B. Das, Pinaki Gupta‐Bhaya

A Comment on the Letter by D. Home and R. Chattopadhyaya, Phys. Rev. Lett. 76, 2836 (1996).Received 22 July 1998DOI:https://doi.org/10.1103/PhysRevLett.84.195©2000 American Physical Society

Physical Review Letters•Jan 3, 2000•1 citation

Comment on “DNA Molecular Cousin of Schrödinger's Cat: A Curious Example of Quantum Measurement”

Philip Pearle, Euan J. Squires

A Comment on the Letter by Dipankar Home and Rajagopal Chattopadhyay, Phys. Rev. Lett. 76, 2836 (1996). The authors of the Letter offer a Reply.Received 30 May 1996DOI:https://doi.org/10.1103/PhysRevLett.80.1348©1998 American Physical Society

Physical Review Letters•Feb 9, 1998•5 citations

On the role of entanglement in Schrödinger’s cat paradox

Stefan Rinner, E. Werner

Abstract In 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.

arXiv:0705.2935•Open Physics•Mar 1, 2008•11 citations

Quantum measurements: cats, clouds and everything else

Lawrence S. Schulman

Quantum measurement theory addresses several problems. All of them arise from applying a microscopically valid theory to the macroscopic domain. The most famous is the Schrödinger cat example in which the ordinary use of quantum rules suggests a superposition of macroscopically different states, something we do not seem to experience. Another problem is the Einstein-Podolsky-Rosen (EPR) paradox in which a fundamental quantum concept, entanglement, creates subtle and non-classical correlations among remote sets of measurements. Although it seems mere word play to observe that such an apparent micro-macro conflict ought to be viewed as a problem in statistical mechanics—by virtue of the way that discipline is defined—until recently the importance of this observation was seldom recognized. The founders, Bohr, Schrödinger, Heisenberg, Einstein did not emphasize this direction, but over the years the realization that measurement necessarily involves macroscopic objects—objects with potentially mischievous degrees of freedom of their own—began to be felt. For me this was brought home by the now classic fourth chapter of Gottfried's text on quantum mechanics. He takes up the following problem. The density matrix ρ 0 for a normalized pure state is ρ 0 = |ψ〉 〈ψ|. It follows that Tr ρ 0 = Tr ρ 0 2 = 1. After a non-trivial measurement, the density matrix ρ is supposed to be diagonal in the basis denned by the measured observable, with Tr ρ = 1 but Tr ρ 2 < 1.

Cambridge University Press eBooks•Jul 31, 1997•0 citations

Schrödinger's cat and her laboratory cousins

A. J. Leggett

In this paper I first briefly review the apparently bizarre consequences of attempting to apply quantum mechanics consistently to macroscopic bodies in certain kinds of situations (the ‘Schrödinger's Cat’ paradox). The paradox results from the assumption that the linear superpositions of macroscopically distinct states, which are unambiguously predicted by the formalism, do indeed exist in nature. Until recently, this assumption was experimentally untested. However, recent advances in techniques of microfabrication, cryogenics and noise control have opened up the possibility of indirect and possibly even direct tests, in particular in superconducting systems incorporating Josephson devices. I describe some of these tests, review the current experimental and theoretical situation and discuss the implications of various possible outcomes to the experiments.

Contemporary Physics•Nov 1, 1984•119 citations

Review and suggested resolution of the problem of Schrodinger’s cat

Art Hobson

This paper reviews and suggests a resolution of the problem of definite outcomes of measurement. This problem, also known as ‘Schrodinger’s cat’, has long posed an apparent paradox because the state resulting from a measurement appears to be a quantum superposition in which the detector is in two macroscopically distinct states (alive and dead in the case of the cat) simultaneously. Many alternative interpretations of the quantum mathematical formalism, and several alternative modifications of the theory, have been proposed to resolve this problem, but no consensus has formed supporting any one of them. Applying standard quantum theory to the measurement state, together with the analysis and results of decades of nonlocality experiments with pairs of entangled systems, this paper shows the entangled measurement state is not a paradoxical macroscopic superposition of states. It is instead a phase-dependent superposition of correlations between states of the subsystems. Thus Schrodinger’s cat is a non-paradoxical ‘macroscopic correlation’ in which one of the two correlated systems happens to be a detector. This insight resolves the problem of definite outcomes but it does not entirely resolve the measurement problem because the entangled state is still reversible.

arXiv:1711.11082•Contemporary Physics•Nov 28, 2017•16 citations
It is argued that ultraviolet absorption by a DNA molecule (which gets biochemically attached to nearby photolyase enzyme so that the effect of uv absorption becomes macroscopically discernible) constitutes an intriguing example of quantum measurement. We point out that this does not merely illustrate the quantum measurement paradox in the hitherto unexplored arena of biological macromolecules, but is also instructive in highlighting specific difficulties inherent in various approaches to the measurement problem.
Abstract In 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.
Quantum measurement theory addresses several problems. All of them arise from applying a microscopically valid theory to the macroscopic domain. The most famous is the Schrödinger cat example in which the ordinary use of quantum rules suggests a superposition of macroscopically different states, something we do not seem to experience. Another problem is the Einstein-Podolsky-Rosen (EPR) paradox in which a fundamental quantum concept, entanglement, creates subtle and non-classical correlations among remote sets of measurements. Although it seems mere word play to observe that such an apparent micro-macro conflict ought to be viewed as a problem in statistical mechanics—by virtue of the way that discipline is defined—until recently the importance of this observation was seldom recognized. The founders, Bohr, Schrödinger, Heisenberg, Einstein did not emphasize this direction, but over the years the realization that measurement necessarily involves macroscopic objects—objects with potentially mischievous degrees of freedom of their own—began to be felt. For me this was brought home by the now classic fourth chapter of Gottfried's text on quantum mechanics. He takes up the following problem. The density matrix ρ 0 for a normalized pure state is ρ 0 = |ψ〉 〈ψ|. It follows that Tr ρ 0 = Tr ρ 0 2 = 1. After a non-trivial measurement, the density matrix ρ is supposed to be diagonal in the basis denned by the measured observable, with Tr ρ = 1 but Tr ρ 2 < 1.
In this paper I first briefly review the apparently bizarre consequences of attempting to apply quantum mechanics consistently to macroscopic bodies in certain kinds of situations (the ‘Schrödinger's Cat’ paradox). The paradox results from the assumption that the linear superpositions of macroscopically distinct states, which are unambiguously predicted by the formalism, do indeed exist in nature. Until recently, this assumption was experimentally untested. However, recent advances in techniques of microfabrication, cryogenics and noise control have opened up the possibility of indirect and possibly even direct tests, in particular in superconducting systems incorporating Josephson devices. I describe some of these tests, review the current experimental and theoretical situation and discuss the implications of various possible outcomes to the experiments.
This paper reviews and suggests a resolution of the problem of definite outcomes of measurement. This problem, also known as ‘Schrodinger’s cat’, has long posed an apparent paradox because the state resulting from a measurement appears to be a quantum superposition in which the detector is in two macroscopically distinct states (alive and dead in the case of the cat) simultaneously. Many alternative interpretations of the quantum mathematical formalism, and several alternative modifications of the theory, have been proposed to resolve this problem, but no consensus has formed supporting any one of them. Applying standard quantum theory to the measurement state, together with the analysis and results of decades of nonlocality experiments with pairs of entangled systems, this paper shows the entangled measurement state is not a paradoxical macroscopic superposition of states. It is instead a phase-dependent superposition of correlations between states of the subsystems. Thus Schrodinger’s cat is a non-paradoxical ‘macroscopic correlation’ in which one of the two correlated systems happens to be a detector. This insight resolves the problem of definite outcomes but it does not entirely resolve the measurement problem because the entangled state is still reversible.