dorsal/arxiv
View SchemaNonlocal Effects of Partial Measurements and Quantum Erasure
| Authors | Avshalom C. Elitzur, Shahar Dolev |
|---|---|
| Categories | |
| ArXiv ID | quant-ph/0012091 |
| URL | https://arxiv.org/abs/quant-ph/0012091 |
| DOI | 10.1103/PhysRevA.63.062109 |
| Journal | Phys. Rev. A 63, 1-14 (2001) |
Abstract
Partial measurement turns the initial superposition not into a definite outcome but into a greater probability for it. The probability can approach 100%, yet the measurement can undergo complete quantum erasure. In the EPR setting, we prove that i) every partial measurement nonlocally creates the same partial change in the distant particle; and ii) every erasure inflicts the same erasure on the distant particle's state. This enables an EPR experiment where the nonlocal effect does not vanish after a single measurement but keeps "traveling" back and forth between particles. We study an experiment in which two distant particles are subjected to interferometry with a partial "which path" measurement. Such a measurement causes a variable amount of correlation between the particles. A new inequality is formulated for same-angle polarizations, extending Bell's inequality for different angles. The resulting nonlocality proof is highly visualizable, as it rests entirely on the interference effect. Partial measurement also gives rise to a new form of entanglement, where the particles manifest correlations of multiple polarization directions. Another novelty in that the measurement to be erased is fully observable, in contrast to prevailing erasure techniques where it can never be observed. Some profound conceptual implications of our experiment are briefly pointed out.
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"abstract": "Partial measurement turns the initial superposition not into a definite\noutcome but into a greater probability for it. The probability can approach\n100%, yet the measurement can undergo complete quantum erasure. In the EPR\nsetting, we prove that i) every partial measurement nonlocally creates the same\npartial change in the distant particle; and ii) every erasure inflicts the same\nerasure on the distant particle\u0027s state. This enables an EPR experiment where\nthe nonlocal effect does not vanish after a single measurement but keeps\n\"traveling\" back and forth between particles. We study an experiment in which\ntwo distant particles are subjected to interferometry with a partial \"which\npath\" measurement. Such a measurement causes a variable amount of correlation\nbetween the particles. A new inequality is formulated for same-angle\npolarizations, extending Bell\u0027s inequality for different angles. The resulting\nnonlocality proof is highly visualizable, as it rests entirely on the\ninterference effect. Partial measurement also gives rise to a new form of\nentanglement, where the particles manifest correlations of multiple\npolarization directions. Another novelty in that the measurement to be erased\nis fully observable, in contrast to prevailing erasure techniques where it can\nnever be observed. Some profound conceptual implications of our experiment are\nbriefly pointed out.",
"arxiv_id": "quant-ph/0012091",
"authors": [
"Avshalom C. Elitzur",
"Shahar Dolev"
],
"categories": [
"quant-ph"
],
"doi": "10.1103/PhysRevA.63.062109",
"journal_ref": "Phys. Rev. A 63, 1-14 (2001)",
"title": "Nonlocal Effects of Partial Measurements and Quantum Erasure",
"url": "https://arxiv.org/abs/quant-ph/0012091"
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