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

Bound state excitation, nucleon decay experiments and models of wave function collapse

Philip Pearle, Euan J. Squires

Published Jul 4, 1994• 175 citations
Publisher

Abstract

We discuss bound state excitation in models where wave function collapse is a physical process. Consequences of a feasible photon counting experiment are spelled out, were an upper limit to be found on the rate of anomalous photon emission from solid matter that is better than 1 photon/sec cc. It is also pointed out that experiments already performed, which give an upper bound on the rate of nucleon decay, can have significant consequences for such models. We show how these experimental results could be considered to rule out the original version of the collapse models, and support a version in which the rate of collapse is proportional to the mass, indicative of a gravitational mechanism.

DOI
10.1103/physrevlett.73.1

Related papers

On the effectiveness of the collapse in the Diósi–Penrose model

Laria Figurato, Marco Dirindin, José Luis Gaona-Reyes +3 more

Abstract The possibility that gravity plays a role in the collapse of the quantum wave function has been considered in the literature, and it is of relevance not only because it would provide a solution to the measurement problem in quantum theory, but also because it would give a new and unexpected twist to the search for a unified theory of quantum and gravitational phenomena, possibly overcoming the current impasse. The Diósi–Penrose model is the most popular incarnation of this idea. It predicts a progressive breakdown of quantum superpositions when the mass of the system increases; as such, it is susceptible to experimental verification. Current experiments set a lower bound R 0 ≳ 4 Å for the free parameter of the model, excluding some versions of it. In this work we search for an upper bound, coming from the request that the collapse is effective enough to guarantee classicality at the macroscopic scale: we find out that not all macroscopic systems collapse effectively. If one relaxes this request, a reasonable (although to some degree arbitrary) bound is found to be: R 0 ≲ 10 6 Å. This will serve to better direct future experiments to further test the model.

arXiv:2406.18494•New Journal of Physics•Oct 29, 2024•12 citations

An Indication From the Magnitude of CP Violations that Gravitation is a Possible Cause of Wave-Function Collapse

Daniel I. Fivel

We consider experimental evidence for the hypothesis that the Planck energy, $E_p \approx 10^{19}GeV$, sets the scale $ε$ at which wave function collapse causes deviations from linear Schrödinger evolution. With a few plausible assumptions about the collapse process, we first show that the observed CP violation in $K_L$ decay implies a lower bound on $ε$ remarkably close to $E_p$. If the bound is saturated, the entire CP violation is due to collapse and a prediction made that the branching ratio for CP violation in the B meson decay will be $γ\approx 10^{-5}$. We then show that the assumptions are consequences of a simple non-linear, stochastic modification of the Schrödinger equation with $ε$ setting the scale of the non-linearity.

arXiv:quant-ph/9710042•Oct 16, 1997•6 citations

On Wave Function Collapse at Radiative Boundaries

Nadav Bashan

The physical mechanism responsible for wave function collapse remains an open question in the foundations of quantum theory. Existing objective reduction models usually rely on gravitational self-energy in the bulk, which makes it difficult to account for the rapid reduction of very light particles and does not naturally address massless quanta such as photons. In this work, a kinematic and mass-independent mechanism for wave function collapse is considered in which radiative emission across a geometric boundary is taken as the operational event associated with reduction. When a single quantum transition is evaluated at a radiative decoupling surface, the governing relation becomes boundary-normalized. Under this formulation both Boltzmann’s constant and Planck’s constant cancel algebraically, and the resulting rate is determined purely by boundary kinematics, Γ ∝ R²ω³ / c². The same structural scaling appears in the standard spontaneous-emission rate derived in quantum electrodynamics, while the fine-structure constant enters only as a dimensionless efficiency factor. Within this framework, quantum states may evolve unitarily in the bulk, whereas any radiative extraction of information into the classical domain must cross a finite decoupling surface. Collapse is therefore interpreted as an objective reduction associated with the finite transmission capacity of a radiative boundary. The Heisenberg cut is consequently assigned a concrete physical location at that boundary.

•Mar 10, 2026•0 citations

Experimental bounds on collapse models from gravitational wave detectors

Matteo Carlesso, Angelo Bassi, P. Falferi +1 more

Wave function collapse models postulate a fundamental breakdown of the quantum superposition principle at the macroscale. Therefore, experimental tests of collapse models are also fundamental tests of quantum mechanics. Here, we compute the upper bounds on the collapse parameters, which can be inferred by the gravitational wave detectors LIGO, LISA Pathfinder, and AURIGA. We consider the most widely used collapse model, the continuous spontaneous localization (CSL) model. We show that these experiments exclude a huge portion of the CSL parameter space, the strongest bound being set by the recently launched space mission LISA Pathfinder. We also rule out a proposal for quantum-gravity-induced decoherence.

arXiv:1606.04581•Physical review. D/Physical review. D.•Dec 23, 2016•154 citations

On the electromagnetic properties of matter in collapse models

Angelo Bassi, Detlef Dürr

We discuss the electromagnetic properties of both a charged free particle, and a charged particle bounded by an harmonic potential, within collapse models. By choosing a particularly simple—yet physically relevant—collapse model, and under only the dipole approximation, we are able to solve the equation of motion exactly. In this way, both the finite-time and large-time behavior can be analyzed accurately. We discovered new features, which did not appear in previous works on the same subject. Since, so far, the spontaneous photon emission process places the strongest upper bounds on the collapse parameters, our results call for a further analysis of this process for those atomic systems which can be employed in experimental tests of collapse models, as well as of quantum mechanics.

arXiv:0908.3398•Journal of Physics A Mathematical and Theoretical•Nov 17, 2009•17 citations

Wave Function Collapse in Atomic Physics

DT Pegg

Wave function collapse has been a contentious concept in quantum mechanics for a considerable time. Here we show examples of how the concept can be used to advantage in predicting the statistical results of three experiments in atomic physics and quantum optics: photon antibunching, single-photon phase difference states and interrupted single-atom fluorescence. We examine the question of whether or not collapse is 'really' a physical process, and discuss the consequences of simply omitting it but including the observer as a part of the overall system governed by the laws of quantum mechanics. The resulting entangled world does not appear to be inconsistent with experience.

Australian Journal of Physics•Feb 1, 1993•8 citations
We discuss bound state excitation in models where wave function collapse is a physical process. Consequences of a feasible photon counting experiment are spelled out, were an upper limit to be found on the rate of anomalous photon emission from solid matter that is better than 1 photon/sec cc. It is also pointed out that experiments already performed, which give an upper bound on the rate of nucleon decay, can have significant consequences for such models. We show how these experimental results could be considered to rule out the original version of the collapse models, and support a version in which the rate of collapse is proportional to the mass, indicative of a gravitational mechanism.
Abstract The possibility that gravity plays a role in the collapse of the quantum wave function has been considered in the literature, and it is of relevance not only because it would provide a solution to the measurement problem in quantum theory, but also because it would give a new and unexpected twist to the search for a unified theory of quantum and gravitational phenomena, possibly overcoming the current impasse. The Diósi–Penrose model is the most popular incarnation of this idea. It predicts a progressive breakdown of quantum superpositions when the mass of the system increases; as such, it is susceptible to experimental verification. Current experiments set a lower bound R 0 ≳ 4 Å for the free parameter of the model, excluding some versions of it. In this work we search for an upper bound, coming from the request that the collapse is effective enough to guarantee classicality at the macroscopic scale: we find out that not all macroscopic systems collapse effectively. If one relaxes this request, a reasonable (although to some degree arbitrary) bound is found to be: R 0 ≲ 10 6 Å. This will serve to better direct future experiments to further test the model.
We consider experimental evidence for the hypothesis that the Planck energy, Ep≈1019GeVE_p \approx 10^{19}GeVEp​≈1019GeV, sets the scale εεε at which wave function collapse causes deviations from linear Schrödinger evolution. With a few plausible assumptions about the collapse process, we first show that the observed CP violation in KLK_LKL​ decay implies a lower bound on εεε remarkably close to EpE_pEp​. If the bound is saturated, the entire CP violation is due to collapse and a prediction made that the branching ratio for CP violation in the B meson decay will be γ≈10−5γ\approx 10^{-5}γ≈10−5. We then show that the assumptions are consequences of a simple non-linear, stochastic modification of the Schrödinger equation with εεε setting the scale of the non-linearity.
The physical mechanism responsible for wave function collapse remains an open question in the foundations of quantum theory. Existing objective reduction models usually rely on gravitational self-energy in the bulk, which makes it difficult to account for the rapid reduction of very light particles and does not naturally address massless quanta such as photons. In this work, a kinematic and mass-independent mechanism for wave function collapse is considered in which radiative emission across a geometric boundary is taken as the operational event associated with reduction. When a single quantum transition is evaluated at a radiative decoupling surface, the governing relation becomes boundary-normalized. Under this formulation both Boltzmann’s constant and Planck’s constant cancel algebraically, and the resulting rate is determined purely by boundary kinematics, Γ ∝ R²ω³ / c². The same structural scaling appears in the standard spontaneous-emission rate derived in quantum electrodynamics, while the fine-structure constant enters only as a dimensionless efficiency factor. Within this framework, quantum states may evolve unitarily in the bulk, whereas any radiative extraction of information into the classical domain must cross a finite decoupling surface. Collapse is therefore interpreted as an objective reduction associated with the finite transmission capacity of a radiative boundary. The Heisenberg cut is consequently assigned a concrete physical location at that boundary.
Wave function collapse models postulate a fundamental breakdown of the quantum superposition principle at the macroscale. Therefore, experimental tests of collapse models are also fundamental tests of quantum mechanics. Here, we compute the upper bounds on the collapse parameters, which can be inferred by the gravitational wave detectors LIGO, LISA Pathfinder, and AURIGA. We consider the most widely used collapse model, the continuous spontaneous localization (CSL) model. We show that these experiments exclude a huge portion of the CSL parameter space, the strongest bound being set by the recently launched space mission LISA Pathfinder. We also rule out a proposal for quantum-gravity-induced decoherence.
We discuss the electromagnetic properties of both a charged free particle, and a charged particle bounded by an harmonic potential, within collapse models. By choosing a particularly simple—yet physically relevant—collapse model, and under only the dipole approximation, we are able to solve the equation of motion exactly. In this way, both the finite-time and large-time behavior can be analyzed accurately. We discovered new features, which did not appear in previous works on the same subject. Since, so far, the spontaneous photon emission process places the strongest upper bounds on the collapse parameters, our results call for a further analysis of this process for those atomic systems which can be employed in experimental tests of collapse models, as well as of quantum mechanics.
Wave function collapse has been a contentious concept in quantum mechanics for a considerable time. Here we show examples of how the concept can be used to advantage in predicting the statistical results of three experiments in atomic physics and quantum optics: photon antibunching, single-photon phase difference states and interrupted single-atom fluorescence. We examine the question of whether or not collapse is 'really' a physical process, and discuss the consequences of simply omitting it but including the observer as a part of the overall system governed by the laws of quantum mechanics. The resulting entangled world does not appear to be inconsistent with experience.