dorsal/arxiv
View SchemaConditional quantum dynamics with several observers
| Authors | Jacek Dziarmaga, Diego A. R. Dalvit, Wojciech H. Zurek |
|---|---|
| Categories | |
| ArXiv ID | quant-ph/0107033 |
| URL | https://arxiv.org/abs/quant-ph/0107033 |
| DOI | 10.1103/PhysRevA.69.022109 |
| Journal | Phys. Rev. A 69, 022109 (2004) |
Abstract
We consider several observers who monitor different parts of the environment of a single quantum system and use their data to deduce its state. We derive a set of conditional stochastic master equations that describe the evolution of the density matrices each observer ascribes to the system under the Markov approximation, and show that this problem can be reduced to the case of a single "super-observer", who has access to all the acquired data. The key problem - consistency of the sets of data acquired by different observers - is then reduced to the probability that a given combination of data sets will be ever detected by the "super-observer". The resulting conditional master equations are applied to several physical examples: homodyne detection of phonons in quantum Brownian motion, photo-detection and homodyne detection of resonance fluorescence from a two-level atom. We introduce {\it relative purity} to quantify the correlations between the information about the system gathered by different observers from their measurements of the environment. We find that observers gain the most information about the state of the system and they agree the most about it when they measure the environment observables with eigenstates most closely correlated with the optimally predictable {\it pointer basis} of the system.
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"abstract": "We consider several observers who monitor different parts of the environment\nof a single quantum system and use their data to deduce its state. We derive a\nset of conditional stochastic master equations that describe the evolution of\nthe density matrices each observer ascribes to the system under the Markov\napproximation, and show that this problem can be reduced to the case of a\nsingle \"super-observer\", who has access to all the acquired data. The key\nproblem - consistency of the sets of data acquired by different observers - is\nthen reduced to the probability that a given combination of data sets will be\never detected by the \"super-observer\". The resulting conditional master\nequations are applied to several physical examples: homodyne detection of\nphonons in quantum Brownian motion, photo-detection and homodyne detection of\nresonance fluorescence from a two-level atom. We introduce {\\it relative\npurity} to quantify the correlations between the information about the system\ngathered by different observers from their measurements of the environment. We\nfind that observers gain the most information about the state of the system and\nthey agree the most about it when they measure the environment observables with\neigenstates most closely correlated with the optimally predictable {\\it pointer\nbasis} of the system.",
"arxiv_id": "quant-ph/0107033",
"authors": [
"Jacek Dziarmaga",
"Diego A. R. Dalvit",
"Wojciech H. Zurek"
],
"categories": [
"quant-ph"
],
"doi": "10.1103/PhysRevA.69.022109",
"journal_ref": "Phys. Rev. A 69, 022109 (2004)",
"title": "Conditional quantum dynamics with several observers",
"url": "https://arxiv.org/abs/quant-ph/0107033"
},
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