Experimental entanglement activation from discord in a programmable quantum measurement

Gerardo Adesso, Vincenzo D'ambrosio, Eleonora Nagali, Marco Piani, Fabio Sciarrino

Research output: Contribution to journalLetter

24 Citations (Scopus)

Abstract

In quantum mechanics, observing is not a passive act. Consider a system of two quantum particles A and B: if a measurement apparatus M is used to make an observation on B, the overall state of the system AB will typically be altered. When this happens, no matter which local measurement is performed, the two objects A and B are revealed to possess peculiar correlations known as quantum discord. Here, we demonstrate experimentally that the very act of local observation gives rise to an activation protocol which converts discord into distillable entanglement, a stronger and more useful form of quantum correlations, between the apparatus M and the composite system AB. We adopt a flexible two-photon setup to realize a three-qubit system (A, B, M) with programmable degrees of initial correlations, measurement interaction, and characterization processes. Our experiment demonstrates the fundamental mechanism underpinning the ubiquitous act of observing the quantum world and establishes the potential of discord in entanglement generation.
LanguageEnglish
Article number140501
Number of pages6
JournalPhysical Review Letters
Volume112
Issue number14
Early online date7 Apr 2014
DOIs
Publication statusPublished - 11 Apr 2014

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activation
quantum mechanics
composite materials
photons
interactions

Keywords

  • entanglement
  • discord
  • quantum optics

Cite this

Adesso, Gerardo ; D'ambrosio, Vincenzo ; Nagali, Eleonora ; Piani, Marco ; Sciarrino, Fabio. / Experimental entanglement activation from discord in a programmable quantum measurement. In: Physical Review Letters. 2014 ; Vol. 112, No. 14.
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Experimental entanglement activation from discord in a programmable quantum measurement. / Adesso, Gerardo; D'ambrosio, Vincenzo; Nagali, Eleonora; Piani, Marco; Sciarrino, Fabio.

In: Physical Review Letters, Vol. 112, No. 14, 140501, 11.04.2014.

Research output: Contribution to journalLetter

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T1 - Experimental entanglement activation from discord in a programmable quantum measurement

AU - Adesso, Gerardo

AU - D'ambrosio, Vincenzo

AU - Nagali, Eleonora

AU - Piani, Marco

AU - Sciarrino, Fabio

N1 - (c) American Physical Society

PY - 2014/4/11

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N2 - In quantum mechanics, observing is not a passive act. Consider a system of two quantum particles A and B: if a measurement apparatus M is used to make an observation on B, the overall state of the system AB will typically be altered. When this happens, no matter which local measurement is performed, the two objects A and B are revealed to possess peculiar correlations known as quantum discord. Here, we demonstrate experimentally that the very act of local observation gives rise to an activation protocol which converts discord into distillable entanglement, a stronger and more useful form of quantum correlations, between the apparatus M and the composite system AB. We adopt a flexible two-photon setup to realize a three-qubit system (A, B, M) with programmable degrees of initial correlations, measurement interaction, and characterization processes. Our experiment demonstrates the fundamental mechanism underpinning the ubiquitous act of observing the quantum world and establishes the potential of discord in entanglement generation.

AB - In quantum mechanics, observing is not a passive act. Consider a system of two quantum particles A and B: if a measurement apparatus M is used to make an observation on B, the overall state of the system AB will typically be altered. When this happens, no matter which local measurement is performed, the two objects A and B are revealed to possess peculiar correlations known as quantum discord. Here, we demonstrate experimentally that the very act of local observation gives rise to an activation protocol which converts discord into distillable entanglement, a stronger and more useful form of quantum correlations, between the apparatus M and the composite system AB. We adopt a flexible two-photon setup to realize a three-qubit system (A, B, M) with programmable degrees of initial correlations, measurement interaction, and characterization processes. Our experiment demonstrates the fundamental mechanism underpinning the ubiquitous act of observing the quantum world and establishes the potential of discord in entanglement generation.

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