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

Direct Measurement of the Longitudinal Coherence Length of a Thermal Neutron Beam

Helmut Kaiser, S. Werner, E. A. George

Published Feb 21, 1983• 124 citations
Publisher

Abstract

When a series of aluminum slabs are placed in one leg of a perfect-silicon-crystal neutron interferometer, a continuous and significant loss of contrast is observed. This observation is interpreted as being due to the finite length of the neutron wave packets.
DOI
10.1103/physrevlett.50.560

Related papers

Neutron phase echo

R. Clothier, Helmut Kaiser, S. A. Werner +2 more

The coherent overlap of the waves traversing the two legs of a perfect-crystal neutron interferometer is altered by a material with a neutron-nuclear optical potential. The fringe visibility is limited by the longitudinal coherence length. The loss of interference contrast caused by a slab of material of positive optical potential can be restored by placing another slab of material with a negative optical potential in the same leg of the interferometer. This paper describes the observation and detailed characterization of this quantum-mechanical phenomenon, which we call the phase-echo effect.

Physical Review A•Nov 1, 1991•47 citations

Elucidation of the neutron coherence length and a matter-wave sideband interferometer

Robert Golub, S. K. Lamoreaux

Physics Letters A•Feb 1, 1992•39 citations

Coherence and spectral filtering in neutron interferometry

Helmut Kaiser, R. Clothier, S. A. Werner +2 more

The coherence length of a neutron wave packet depends on the spectral width of the distribution of wave vectors that make up the packet. The coherent overlap of the wave packets traversing the two beam paths in a perfect-silicon-crystal neutron interferometer (NI) is altered by placing a material with a neutron-nuclear optical potential in one of the beam paths in the NI. If the optical potential is positive, it causes a delay of the wave packet and a loss of fringe visibility. By use of an analyzer crystal, we narrow the spectral distribution after the mixing and interference has occurred in the last crystal slab of the NI. This increases the coherence length and restores some of the fringe visibility.

Physical Review A•Jan 1, 1992•65 citations

Further remarks on the coherence properties of a thermal neutron beam

S. Boffi, Giuseppe Caglioti

Il Nuovo cimento della Società italiana di fisica. B/Il Nuovo cimento B•Jun 1, 1971•7 citations

Measurements of the Vertical Coherence Length in Neutron Interferometry

Dmitry A. Pushin, M. Arif, M. G. Huber +1 more

The study and use of macroscopic quantum coherence requires long coherence lengths. Here we describe an approach to measuring the vertical coherence length in neutron interferometry, along with improvements to the NIST interferometer that led to a measured coherence length of 790 A. The measurement is based on introducing a path separation and measuring the loss in contrast as this separation is increased. The measured coherence length is consistent with the momentum distribution of the neutron beam. Finally, we demonstrate that the loss in contrast with beam displacement in one leg of the interferometer can be recovered by introducing a corresponding displacement in the second leg.

Physical Review Letters•Jun 26, 2008•30 citations

Precisison neutron interferometric measurement of the nd coherent scattering length

William Michael Snow, T. Black, Muhammad Arif +6 more

APS•Nov 1, 2003•0 citations
The coherent overlap of the waves traversing the two legs of a perfect-crystal neutron interferometer is altered by a material with a neutron-nuclear optical potential. The fringe visibility is limited by the longitudinal coherence length. The loss of interference contrast caused by a slab of material of positive optical potential can be restored by placing another slab of material with a negative optical potential in the same leg of the interferometer. This paper describes the observation and detailed characterization of this quantum-mechanical phenomenon, which we call the phase-echo effect.
The coherence length of a neutron wave packet depends on the spectral width of the distribution of wave vectors that make up the packet. The coherent overlap of the wave packets traversing the two beam paths in a perfect-silicon-crystal neutron interferometer (NI) is altered by placing a material with a neutron-nuclear optical potential in one of the beam paths in the NI. If the optical potential is positive, it causes a delay of the wave packet and a loss of fringe visibility. By use of an analyzer crystal, we narrow the spectral distribution after the mixing and interference has occurred in the last crystal slab of the NI. This increases the coherence length and restores some of the fringe visibility.
The study and use of macroscopic quantum coherence requires long coherence lengths. Here we describe an approach to measuring the vertical coherence length in neutron interferometry, along with improvements to the NIST interferometer that led to a measured coherence length of 790 A. The measurement is based on introducing a path separation and measuring the loss in contrast as this separation is increased. The measured coherence length is consistent with the momentum distribution of the neutron beam. Finally, we demonstrate that the loss in contrast with beam displacement in one leg of the interferometer can be recovered by introducing a corresponding displacement in the second leg.