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 Rochester Conferences on Coherence and Quantum Optics and the Quantum Information and Measurement meeting

Nonlocal Interferometry Using Schrodinger Cats

J. D. Franson

Published Jan 1, 2013• 0 citations
Publisher

Abstract

A method for performing nonlocal interferometry using macroscopic phase-entangled coherent states is described. This allows Bell’s inequality to be violated using Schrodinger cat states over relatively large distances in optical fibers.
DOI
10.1364/cqo.2013.t1.1

Related papers

Nonlocal interferometry using macroscopic coherent states and weak nonlinearities

Brian T. Kirby, J. D. Franson

A method for performing nonlocal interferometry using phase-entangled macroscopic coherent states is described. The required entanglement can be generated using weak nonlinearities while Bell's inequality can be violated using single photons as a probe. The entanglement is relatively robust against photon loss and Bell's inequality can be violated over a relatively large distance in optical fibers despite the fact that a large number of photons are absorbed in the process.

arXiv:1207.5487•Physical Review A•May 17, 2013•39 citations

Macroscopic state interferometry over large distances using state discrimination

Brian T. Kirby, J. D. Franson

The propagation of macroscopic entangled states over large distances in the presence of loss is of fundamental interest and may have practical applications as well. Here we describe two different techniques in which state discrimination can be used to violate Bell's inequality with macroscopic phase-entangled coherent states. We find that Bell's inequality can be violated by these macroscopic states over a distance of approximately 400 km in commercially available optical fibers.

arXiv:1310.1846•Physical Review A•Mar 31, 2014•21 citations

Nonlocal Interferometry Using Macroscopic States and State Discrimination

Brian T. Kirby, J. D. Franson

A nonlocal interferometer that can violate Bell’s inequality using macroscopic phase-entangled coherent states is described. An operating range of 400 km in optical fiber can be achieved using state discrimination techniques.

•Jan 1, 2014•0 citations

Nonlocality of the Schrödinger cat

Krzysztof Wódkiewicz

The nonlocality of the Schrödinger cat is established. A correlation measurement that exhibits quantum interference in the form of the Wigner function of the cat state is introduced. The relation of this correlation to quantum interference in phase space and the nonlocal character of the Schrödinger cat are discussed. It is shown that the Schrödinger cat correlation function leads to violation of the Bell inequality for macroscopically distinguishable states of the cat.

New Journal of Physics•Sep 12, 2000•30 citations

Nonlocal Interferometry with Macroscopic Coherent States and its Application to Quantum Communications

Brian T. Kirby

Macroscopic quantum effects are of fundamental interest because they help us to understand the quantum-classical boundary, and may also have important practical applications in long-range quantum communications. Specifically we analyze a macroscopic generalization of the Franson interferometer, where violations of Bell's inequality can be observed using phase entangled coherent states created using weak nonlinearities. Furthermore we want to understand how these states, and other macroscopic quantum states, can be applied to secure quantum communications. We find that Bell's inequality can be violated at ranges of roughly 400 km in optical fiber when various unambiguous state discrimination techniques are applied. In addition Monte Carlo simulations suggest that quantum communications schemes based on macroscopic quantum states and random unitary transformations can be potentially secure at long distances. Lastly, we calculate the feasibility of creating the weak nonlinearity needed for the experimental realization of these proposals using metastable xenon in a high finesse cavity. This research suggests that quantum states created using macroscopic coherent states and weak nonlinearities may be a realistic path towards the realization of secure long-range quantum communications.

•Jan 1, 2015•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
Macroscopic quantum effects are of fundamental interest because they help us to understand the quantum-classical boundary, and may also have important practical applications in long-range quantum communications. Specifically we analyze a macroscopic generalization of the Franson interferometer, where violations of Bell's inequality can be observed using phase entangled coherent states created using weak nonlinearities. Furthermore we want to understand how these states, and other macroscopic quantum states, can be applied to secure quantum communications. We find that Bell's inequality can be violated at ranges of roughly 400 km in optical fiber when various unambiguous state discrimination techniques are applied. In addition Monte Carlo simulations suggest that quantum communications schemes based on macroscopic quantum states and random unitary transformations can be potentially secure at long distances. Lastly, we calculate the feasibility of creating the weak nonlinearity needed for the experimental realization of these proposals using metastable xenon in a high finesse cavity. This research suggests that quantum states created using macroscopic coherent states and weak nonlinearities may be a realistic path towards the realization of secure long-range quantum communications.
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.