dorsal/arxiv
View SchemaEntanglement witnesses and a loophole problem
| Authors | Patrick Skwara, Hermann Kampermann, Matthias Kleinmann, Dagmar Bruss |
|---|---|
| Categories | |
| ArXiv ID | quant-ph/0608058 |
| URL | https://arxiv.org/abs/quant-ph/0608058 |
| DOI | 10.1103/PhysRevA.76.012312 |
| Journal | Phys. Rev. A 76, 012312 (2007) |
Abstract
We consider a possible detector-efficiency loophole in experiments that detect entanglement via the local measurement of witness operators. Here, only local properties of the detectors are known. We derive a general threshold for the detector efficiencies which guarantees that a negative expectation value of a witness is due to entanglement, rather than to erroneous detectors. This threshold depends on the local decomposition of the witness and its measured expectation value. For two-qubit witnesses we find the local operator decomposition that is optimal with respect to closing the loophole.
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"abstract": "We consider a possible detector-efficiency loophole in experiments that\ndetect entanglement via the local measurement of witness operators. Here, only\nlocal properties of the detectors are known. We derive a general threshold for\nthe detector efficiencies which guarantees that a negative expectation value of\na witness is due to entanglement, rather than to erroneous detectors. This\nthreshold depends on the local decomposition of the witness and its measured\nexpectation value. For two-qubit witnesses we find the local operator\ndecomposition that is optimal with respect to closing the loophole.",
"arxiv_id": "quant-ph/0608058",
"authors": [
"Patrick Skwara",
"Hermann Kampermann",
"Matthias Kleinmann",
"Dagmar Bruss"
],
"categories": [
"quant-ph"
],
"doi": "10.1103/PhysRevA.76.012312",
"journal_ref": "Phys. Rev. A 76, 012312 (2007)",
"title": "Entanglement witnesses and a loophole problem",
"url": "https://arxiv.org/abs/quant-ph/0608058"
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