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

Journal of Physics Conference Series

Measuring the weak value of momentum in a double slit atom interferometer

James G. Morley, P. D. Edmunds, P. F. Barker

Published Mar 1, 2016• 10 citations
Publisher

Abstract

We describe the development of an experiment to measure the weak value of the transverse momentum operator (local momentum [1]) of cold atoms passing through a matter- wave interferometer. The results will be used to reconstruct the atom's average trajectories. We describe our progress towards this goal using laser cooled argon atoms.

DOI
10.1088/1742-6596/701/1/012030

Related papers

Towards a weak measurement of transverse momentum in a matter-wave interferometer

Joel Morley

This thesis describes the construction of an atomic matter-wave interferometer, combined with a spin-state interferometer, used to weakly measure the average transverse momentum of the atoms. A velocity-tuneable cold atomic beam was constructed and characterised. By applying radiation pressure to a magneto-optical trap, the beam's velocity was selected between 1-52 ms-1. The beam was used to produce interference fringes in a matter-wave interferometer which consisted of a mutli-slit Si3Ni4 grating and a planar atom detector placed below the grating. The interference pattern was used to measure the average beam velocity and the Van der Waals coefficient between the atoms and the grating. This was the first instance of such a measurement. Below the grating a longitudinal Stern-Gerlach interferometer was constructed. The phase shift of the atom's spin, due to the Zeeman effect from the interferometer's magnetic field, was measured. The phase shift provided a measurement of the interferometer's magnetic field in the μT range. An experiment combining the two interferometers to weakly measure the atom's transverse momentum is described and modelled.

•Nov 28, 2020•1 citation

Observing the Average Trajectories of Single Photons in a Two-Slit Interferometer

Sacha Kocsis, Boris Braverman, Sylvain Ravets +4 more

We reconstruct the trajectories of single photons in a two-slit interferometer, by weakly measuring photon momentum, and post-selecting on the result of a strong measurement of photon position in a series of planes.

•Jan 1, 2011•26 citations

Observing the average trajectories of single photons in a two-slit interferometer

Sacha Kocsis, Boris Braverman, Sylvain Ravets +4 more

We reconstruct the trajectories of single photons in a two-slit interferometer, by weakly measuring photon momentum, and post-selecting on the result of a strong measurement of photon position in a series of planes.

•Aug 1, 2011•17 citations

Observing the Average Trajectories of Single Photons in a Two-Slit Interferometer

Sacha Kocsis, Boris Braverman, Sylvain Ravets +4 more

A consequence of the quantum mechanical uncertainty principle is that one may not discuss the path or "trajectory" that a quantum particle takes, because any measurement of position irrevocably disturbs the momentum, and vice versa. Using weak measurements, however, it is possible to operationally define a set of trajectories for an ensemble of quantum particles. We sent single photons emitted by a quantum dot through a double-slit interferometer and reconstructed these trajectories by performing a weak measurement of the photon momentum, postselected according to the result of a strong measurement of photon position in a series of planes. The results provide an observationally grounded description of the propagation of subensembles of quantum particles in a two-slit interferometer.

Science•Jun 3, 2011•649 citations

Photon trajectories, anomalous velocities and weak measurements: a classical interpretation

Konstantin Yu Bliokh, A. Ya. Bekshaev, Abraham G. Kofman +1 more

Recently, Kocsis et al (2011 Science 332 1170) reported the observation of 'average trajectories of single photons' in a two-slit interference experiment. This was possible by using the quantum weak-measurement method, which implies averaging over many events, i.e. in fact, a multi-photon limit of classical linear optics. We give a classical-optics interpretation of this experiment and other related problems. It appears that weak measurements of the local momentum of photons made by Kocsis et al represent measurements of the Poynting vector in an optical field. We consider both the real and imaginary parts of the local momentum and show that their measurements have been realized in classical optics using small-probe particles. We also examine the appearance of 'anomalous' values of the local momentum: either negative (backflow) or exceeding the wavenumber (superluminal propagation). These features appear to be closely related to vortices and evanescent waves. Finally, we revisit a number of older works and find examples of photon trajectories and anomalous-momentum measurements in various optical experiments.

arXiv:1304.1276•New Journal of Physics•Jul 9, 2013•128 citations

Measuring the quantum state of cold atoms using momentum-shearing interferometry

Ian A. Walmsley, N. P. Bigelow

We describe a method for measuring the density matrix of the transverse component of an atomic beam using a two-color, double-grating lateral shearing interferometer. From a set of measurements made in the far field of the atom interferometer, it is possible to reconstruct the one-particle density matrix with a very simple algorithm that involves no integral transforms.

Physical Review A•Feb 1, 1998•10 citations
We describe the development of an experiment to measure the weak value of the transverse momentum operator (local momentum [1]) of cold atoms passing through a matter- wave interferometer. The results will be used to reconstruct the atom's average trajectories. We describe our progress towards this goal using laser cooled argon atoms.
This thesis describes the construction of an atomic matter-wave interferometer, combined with a spin-state interferometer, used to weakly measure the average transverse momentum of the atoms. A velocity-tuneable cold atomic beam was constructed and characterised. By applying radiation pressure to a magneto-optical trap, the beam's velocity was selected between 1-52 ms-1. The beam was used to produce interference fringes in a matter-wave interferometer which consisted of a mutli-slit Si3Ni4 grating and a planar atom detector placed below the grating. The interference pattern was used to measure the average beam velocity and the Van der Waals coefficient between the atoms and the grating. This was the first instance of such a measurement. Below the grating a longitudinal Stern-Gerlach interferometer was constructed. The phase shift of the atom's spin, due to the Zeeman effect from the interferometer's magnetic field, was measured. The phase shift provided a measurement of the interferometer's magnetic field in the μT range. An experiment combining the two interferometers to weakly measure the atom's transverse momentum is described and modelled.
A consequence of the quantum mechanical uncertainty principle is that one may not discuss the path or "trajectory" that a quantum particle takes, because any measurement of position irrevocably disturbs the momentum, and vice versa. Using weak measurements, however, it is possible to operationally define a set of trajectories for an ensemble of quantum particles. We sent single photons emitted by a quantum dot through a double-slit interferometer and reconstructed these trajectories by performing a weak measurement of the photon momentum, postselected according to the result of a strong measurement of photon position in a series of planes. The results provide an observationally grounded description of the propagation of subensembles of quantum particles in a two-slit interferometer.
Recently, Kocsis et al (2011 Science 332 1170) reported the observation of 'average trajectories of single photons' in a two-slit interference experiment. This was possible by using the quantum weak-measurement method, which implies averaging over many events, i.e. in fact, a multi-photon limit of classical linear optics. We give a classical-optics interpretation of this experiment and other related problems. It appears that weak measurements of the local momentum of photons made by Kocsis et al represent measurements of the Poynting vector in an optical field. We consider both the real and imaginary parts of the local momentum and show that their measurements have been realized in classical optics using small-probe particles. We also examine the appearance of 'anomalous' values of the local momentum: either negative (backflow) or exceeding the wavenumber (superluminal propagation). These features appear to be closely related to vortices and evanescent waves. Finally, we revisit a number of older works and find examples of photon trajectories and anomalous-momentum measurements in various optical experiments.