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Physical Review A

Investigation of the collapse of quantum states using entangled photons

George Moreno, Fernando Parisio

Published Jul 19, 2013• 4 citations
Publisher

Abstract

We propose a scheme to investigate the time scale of wave-function collapse by using polarization-entangled photon pairs. The setup is similar to those employed to study quantum correlations, but in the present case, synchronization is essential at all stages. We find that it is possible to discriminate between the scenarios of instantaneous collapse and finite-time reduction via a large number of double measurements of polarization. The quantities to be recorded present distinct behaviors in each scenario, the deviations being small but distinguishable from pure statistical fluctuations. The connection between the presented formalism and the theory of weak measurements is discussed as well as the possible consequences for experimental tests of nonlocality.

DOI
10.1103/physreva.88.012118

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We propose a scheme to investigate the time scale of wave-function collapse by using polarization-entangled photon pairs. The setup is similar to those employed to study quantum correlations, but in the present case, synchronization is essential at all stages. We find that it is possible to discriminate between the scenarios of instantaneous collapse and finite-time reduction via a large number of double measurements of polarization. The quantities to be recorded present distinct behaviors in each scenario, the deviations being small but distinguishable from pure statistical fluctuations. The connection between the presented formalism and the theory of weak measurements is discussed as well as the possible consequences for experimental tests of nonlocality.
We propose a scheme to investigate the time scale of the wave-function collapse by using polarization-entangled photon pairs. The setup is similar to those employed to investigate quantum correlations, but in the present case, synchronization is essential at all stages. We find that it is possible to discriminate between the scenarios of instantaneous collapse and finite-time reduction via a large number of double measurements of polarization. The quantities to be recorded would present distinct behaviors in each scenario, the deviations being small but distinguishable from pure statistical fluctuations.
Wavefunction collapse is a puzzling aspect of quantum mechanics. Designing a test to confirm the instantaneousness of collapse has turned out to be challenging, especially for collapse in configuration space. We propose a test using two identical, non-local, correlated photons in an interferometer in which a post-selection measurement of one of the photons in its location changes the statistical behavior of the other photon, which is an arbitrarily large distance away, and thus its detectable subsequent behavior. Analysis of the resulting correlations constitutes a test of the instantaneousness (or non-instantaneousness) of collapse. Connections to some of the recent proposed models of collapse are discussed
The instantaneous nature of quantum entanglement remains one of the most intriguing aspects of quantum mechanics. While the no-signaling theorem prohibits faster-than-light communication, the concept of a finite speed for the collapse of the quantum wavefunction has been a subject of philosophical debate. In this paper, we propose an experimental setup designed to test the speed of wavefunction collapse using entangled photon pairs over a distance of 10 km. By systematically varying the time delay between measurements and analyzing the resulting correlations, we aim to outline a method that could place bounds on the collapse speed without contradicting the no-signaling theorem. We argue that detecting a finite, possibly superluminal, speed of collapse could allow for maintaining realism and locality through high-speed remote synchronization, eliminating the need for hidden variables. We provide a detailed experimental design, including an algorithm and a Python implementation using the Cirq library to simulate the proposed experiment. Our goal is to motivate experimentalists to undertake this test, which could have profound implications for our understanding of quantum mechanics and the nature of reality.
The instantaneous nature of quantum entanglement remains one of the most intriguing aspects of quantum mechanics. While the no-signaling theorem prohibits faster-than-light communication, the concept of a finite speed for the collapse of the quantum wavefunction has been a subject of philosophical debate. In this paper, we propose an experimental setup designed to test the speed of wavefunction collapse using entangled photon pairs over a distance of 10 km. By systematically varying the time delay between measurements and analyzing the resulting correlations, we aim to outline a method that could place bounds on the collapse speed without contradicting the no-signaling theorem. We argue that detecting a finite, possibly superluminal, speed of collapse could allow for maintaining realism and locality through high-speed remote synchronization, eliminating the need for hidden variables. We provide a detailed experimental design, including an algorithm and a Python implementation using the Cirq library to simulate the proposed experiment. Our goal is to motivate experimentalists to undertake this test, which could have profound implications for our understanding of quantum mechanics and the nature of reality.
This paper proposes an experiment designed to distinguish between competing interpretations of quantum mechanics: those that involve wave function collapse and those that assume purely unitary evolution. The experiment tests whether an observer can measure a system without collapsing its wave function. To this end, we introduce the concept of an unconscious observer, defined by two criteria: (1) It measures a quantum system and sets the state of another system based on the result. (2) It allows an external experimentalist to infer the measurement outcome by examining the observer's state. The more distinguishable the observer's resulting states, the more it resembles a conventional measurement apparatus. Using weak measurements, the experimentalist probes these states, thereby testing the second criterion. The interference patterns observed in this setup reveal whether collapse has occurred, allowing experimental discrimination between collapse-based and unitary interpretations.
It is well established that starting only with strong, projective quantum measurements, experiments can be designed to allow weak measurements, which lead to a random walk between the possible final measurement outcomes. However, one can ask the reverse question: starting with only weak measurements, can all the results of standard strong measurements be recovered? Prior work has shown that some results can be, such as the Born rule for the probability of measurement outcomes as a function of wave intensity. In this paper, we show that another crucial result can be reproduced by purely weak measurements, namely, the collapse of a many-body, nonlocally entangled wave function on a timescale comparable to the characteristic time of a single, local measurement. For an entangled state of a single excitation among NNN qubits, we find the collapse time scales as a double logarithm of NNN. This result affirms the self-consistency of the hypothesis that spontaneous weak measurements lie at the base of all physical measurements, independent of human observers.