dorsal/arxiv
View SchemaA Discrete Phase-Space Calculus for Quantum Spins based on a Reconstruction Method using Coherent States
| Authors | Stefan Weigert |
|---|---|
| Categories | |
| ArXiv ID | quant-ph/9904095 |
| URL | https://arxiv.org/abs/quant-ph/9904095 |
Abstract
To reconstruct a mixed or pure quantum state of a spin s is possible through coherent states: its density matrix is fixed by the probabilities to measure the value s along 4s(s+1) appropriately chosen directions in space. Thus, after inverting the experimental data, the statistical operator is parametrized entirely by expectation values. On this basis, a symbolic calculus for quantum spins is developed, the `expectation-value representation.' It resembles the Moyal representation for SU(2) but two important differences exist. On the one hand, the symbols take values on a discrete set of points in phase space only. On the other hand, no quasi-probabilities - that is, phase-space distributions with negative values - are encountered in this approach.
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"abstract": "To reconstruct a mixed or pure quantum state of a spin s is possible through\ncoherent states: its density matrix is fixed by the probabilities to measure\nthe value s along 4s(s+1) appropriately chosen directions in space. Thus, after\ninverting the experimental data, the statistical operator is parametrized\nentirely by expectation values. On this basis, a symbolic calculus for quantum\nspins is developed, the `expectation-value representation.\u0027 It resembles the\nMoyal representation for SU(2) but two important differences exist. On the one\nhand, the symbols take values on a discrete set of points in phase space only.\nOn the other hand, no quasi-probabilities - that is, phase-space distributions\nwith negative values - are encountered in this approach.",
"arxiv_id": "quant-ph/9904095",
"authors": [
"Stefan Weigert"
],
"categories": [
"quant-ph"
],
"title": "A Discrete Phase-Space Calculus for Quantum Spins based on a Reconstruction Method using Coherent States",
"url": "https://arxiv.org/abs/quant-ph/9904095"
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