### Abstract

We investigate the complexity cost of demonstrating the key types of nonclassical correlations-Bell inequality violation, Einstein, Podolsky, Rosen (EPR)-steering, and entanglement-with independent agents, theoretically and in a photonic experiment. We show that the complexity cost exhibits a hierarchy among these three tasks, mirroring the recently discovered hierarchy for how robust they are to noise. For Bell inequality violations, the simplest test is the well-known Clauser-Horne-Shimony-Holt test, but for EPR-steering and entanglement the tests that involve the fewest number of detection patterns require nonprojective measurements. The simplest EPR-steering test requires a choice of projective measurement for one agent and a single nonprojective measurement for the other, while the simplest entanglement test uses just a single nonprojective measurement for each agent. In both of these cases, we derive our inequalities using the concept of circular two-designs. This leads to the interesting feature that in our photonic demonstrations, the correlation of interest is independent of the angle between the linear polarizers used by the two parties, which thus require no alignment.

Original language | English |
---|---|

Article number | 113020 |

Number of pages | 12 |

Journal | New Journal of Physics |

Volume | 14 |

DOIs | |

Publication status | Published - 15 Nov 2012 |

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### Keywords

- measurement theory
- quantum theory
- optics
- lasers

### Cite this

*New Journal of Physics*,

*14*, [113020]. https://doi.org/10.1088/1367-2630/14/11/113020

}

*New Journal of Physics*, vol. 14, 113020. https://doi.org/10.1088/1367-2630/14/11/113020

**The simplest demonstrations of quantum nonlocality.** / Saunders, Dylan J.; Palsson, Matthew S.; Pryde, Geoff J.; Scott, Andrew J.; Barnett, Stephen M.; Wiseman, Howard M.

Research output: Contribution to journal › Article

TY - JOUR

T1 - The simplest demonstrations of quantum nonlocality

AU - Saunders, Dylan J.

AU - Palsson, Matthew S.

AU - Pryde, Geoff J.

AU - Scott, Andrew J.

AU - Barnett, Stephen M.

AU - Wiseman, Howard M.

PY - 2012/11/15

Y1 - 2012/11/15

N2 - We investigate the complexity cost of demonstrating the key types of nonclassical correlations-Bell inequality violation, Einstein, Podolsky, Rosen (EPR)-steering, and entanglement-with independent agents, theoretically and in a photonic experiment. We show that the complexity cost exhibits a hierarchy among these three tasks, mirroring the recently discovered hierarchy for how robust they are to noise. For Bell inequality violations, the simplest test is the well-known Clauser-Horne-Shimony-Holt test, but for EPR-steering and entanglement the tests that involve the fewest number of detection patterns require nonprojective measurements. The simplest EPR-steering test requires a choice of projective measurement for one agent and a single nonprojective measurement for the other, while the simplest entanglement test uses just a single nonprojective measurement for each agent. In both of these cases, we derive our inequalities using the concept of circular two-designs. This leads to the interesting feature that in our photonic demonstrations, the correlation of interest is independent of the angle between the linear polarizers used by the two parties, which thus require no alignment.

AB - We investigate the complexity cost of demonstrating the key types of nonclassical correlations-Bell inequality violation, Einstein, Podolsky, Rosen (EPR)-steering, and entanglement-with independent agents, theoretically and in a photonic experiment. We show that the complexity cost exhibits a hierarchy among these three tasks, mirroring the recently discovered hierarchy for how robust they are to noise. For Bell inequality violations, the simplest test is the well-known Clauser-Horne-Shimony-Holt test, but for EPR-steering and entanglement the tests that involve the fewest number of detection patterns require nonprojective measurements. The simplest EPR-steering test requires a choice of projective measurement for one agent and a single nonprojective measurement for the other, while the simplest entanglement test uses just a single nonprojective measurement for each agent. In both of these cases, we derive our inequalities using the concept of circular two-designs. This leads to the interesting feature that in our photonic demonstrations, the correlation of interest is independent of the angle between the linear polarizers used by the two parties, which thus require no alignment.

KW - measurement theory

KW - quantum theory

KW - optics

KW - lasers

UR - http://www.scopus.com/inward/record.url?scp=84870441073&partnerID=8YFLogxK

U2 - 10.1088/1367-2630/14/11/113020

DO - 10.1088/1367-2630/14/11/113020

M3 - Article

VL - 14

JO - New Journal of Physics

JF - New Journal of Physics

SN - 1367-2630

M1 - 113020

ER -