dorsal/arxiv
View SchemaMeasuring quantum states: an experimental setup for measuring the spatial density matrix
| Authors | Max Tegmark |
|---|---|
| Categories | |
| ArXiv ID | quant-ph/9607021 |
| URL | https://arxiv.org/abs/quant-ph/9607021 |
| DOI | 10.1103/PhysRevA.54.2703 |
| Journal | Phys Rev A, 54, 2703 (1996) |
Abstract
To quantify the effect of decoherence in quantum measurements, it is desirable to measure not merely the square modulus of the spatial wavefunction, but the entire density matrix, whose phases carry information about momentum and how pure the state is. An experimental setup is presented which can measure the density matrix (or equivalently, the Wigner function) of a beam of identically prepared charged particles to an arbitrary accuracy, limited only by count statistics and detector resolution. The particles enter into an electric field causing simple harmonic oscillation in the transverse direction. This corresponds to rotating the Wigner function in phase space. With a slidable detector, the marginal distribution of the Wigner function can be measured from all angles. Thus the phase-space tomography formalism can be used to recover the Wigner function by the standard inversion of the Radon transform. By applying this technique to for instance double-slit experiments with various degrees of environment-induced decoherence, it should be possible to make our understanding of decoherence and apparent wave-function collapse less qualitative and more quantitative.
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"abstract": "To quantify the effect of decoherence in quantum measurements, it is\ndesirable to measure not merely the square modulus of the spatial wavefunction,\nbut the entire density matrix, whose phases carry information about momentum\nand how pure the state is. An experimental setup is presented which can measure\nthe density matrix (or equivalently, the Wigner function) of a beam of\nidentically prepared charged particles to an arbitrary accuracy, limited only\nby count statistics and detector resolution. The particles enter into an\nelectric field causing simple harmonic oscillation in the transverse direction.\nThis corresponds to rotating the Wigner function in phase space. With a\nslidable detector, the marginal distribution of the Wigner function can be\nmeasured from all angles. Thus the phase-space tomography formalism can be used\nto recover the Wigner function by the standard inversion of the Radon\ntransform. By applying this technique to for instance double-slit experiments\nwith various degrees of environment-induced decoherence, it should be possible\nto make our understanding of decoherence and apparent wave-function collapse\nless qualitative and more quantitative.",
"arxiv_id": "quant-ph/9607021",
"authors": [
"Max Tegmark"
],
"categories": [
"quant-ph"
],
"doi": "10.1103/PhysRevA.54.2703",
"journal_ref": "Phys Rev A, 54, 2703 (1996)",
"title": "Measuring quantum states: an experimental setup for measuring the spatial density matrix",
"url": "https://arxiv.org/abs/quant-ph/9607021"
},
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