Observing interferences between past and future quantum states in resonance fluorescence

Abstract : In quantum physics, measurement results are random but their statistics can be predicted assuming some knowledge about the system in the past. Additional knowledge from a future measurement deeply changes the statistics in the present and leads to purely quantum features. In particular conditioned average outcomes of a weak measurement, so-called weak values, were shown to go beyond the conventional range, give a way to directly measure complex quantities, and can be used to enhance the sensitivity of quantum meters. Recently, these concepts have been considered in the general case of open quantum systems where decoherence occurs. Then, what are the properties of weak values for the unavoidable measurement associated to decoherence, the one performed by the environment? Here, we answer this question in the simplest open quantum system: a quantum bit in presence of a relaxation channel. We continuously monitor the fluorescence emitted by a superconducting qubit driven at resonance. Conditioned on initial preparation and final single shot measurement outcome of the qubit state, we probe weak values displaying all the above properties. The fluorescence signal exhibits interferences between oscillations associated to past and future quantum states. The measured data are in complete agreement with theory.
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Article dans une revue
Physical Review Letters, American Physical Society, 2014, 112, pp.180402. 〈10.1103/PhysRevLett.112.180402〉
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https://hal.archives-ouvertes.fr/hal-00909983
Contributeur : Benjamin Huard <>
Soumis le : mercredi 27 novembre 2013 - 11:09:18
Dernière modification le : mardi 14 novembre 2017 - 11:08:03

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Philippe Campagne-Ibarcq, Landry Bretheau, Emmanuel Flurin, Alexia Auffèves, François Mallet, et al.. Observing interferences between past and future quantum states in resonance fluorescence. Physical Review Letters, American Physical Society, 2014, 112, pp.180402. 〈10.1103/PhysRevLett.112.180402〉. 〈hal-00909983〉

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