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Weak-value amplification of the nonlinear effect of a single photon

Nature Physics 13
Hallaji, M.Feizpour, A.Dmochowski, G.Sinclair, J.Steinberg, A.M. Department of Physics,
Centre for Quantum Information and Quantum Control
Institute for Optical Sciences,
University of Toronto, Ontario, Canada

Canadian Institute For Advanced Research,
Toronto, Ontario, Canada
2017 Physics

In quantum mechanics, the concept of weak measurements allows for the description of a quantum system both in terms of the initial preparation and the final state (post-selection)1. This paradigm has been extensively studied theoretically and experimentally, but almost all of weak-measurement experiments carried out to date can be understood in terms of the classical (electromagnetic wave) theory of optics.

Here, we present a quantum version in which the measurement apparatus deterministically entangles two distinct optical beams. We show that a single photon, when properly post-selected, can have an effect equal to that of eight photons: that is, in a system where a single photon has been calibrated to write a nonlinear phase shift of φo on a probe beam, we measure phase shifts as large as 8φo for appropriately post-selected single photons.

This opens up a new regime for the study of entanglement of optical beams, as well as further investigations of the power of weak-value amplification for the measurement of small quantities.

The article was published in: Nature Physics 13: 540.

Full article

This work was supported (in part) by the Fetzer Franklin Fund of the John E. Fetzer Memorial Trust.