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- Björk, Gunnar, et al.
(författare)
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Visibility is not a good measure of a well-defined relative phase
- 2000
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 6202:2
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Tidskriftsartikel (refereegranskat)abstract
- In a recent paper Marburger and Das [J. H. Marburger III and K. K. Das, Phys. Rev. A 59, 2213 (1999)] considered an interference visibility experiment involving two weakly interacting Bose-Einstein condensates. It was shown that condensate eigenstates of the Hermitian relative phase operator do not give interference fringes with unit visibility in a Young's double slit type of experiment. The authors concluded that ... these states are not especially well suited to describe weakly interacting multiply occupied coherent bosonic systems. In this work we suggest a criterion for states with a well-defined relative phase. Subsequently we show that the relative phase operator eigenstates satisfy this criterion. This suggests that the concept of interference visibility can, and should, be generalized, since it is widely believed that interference visibility is a measure of the relative phase properties. We therefore propose a broader, but still operational, definition of interference visibility, which we call generalized visibility, and prove that the relative phase operator eigenstates indeed can show unit generalized visibility. We also derive a simple, but general, criterion for states which can display a unit generalized visibility. Somewhat surprisingly, this criterion is weaker than the criterion for a well-defined relative phase. Finally, we discuss which two-mode states can display unit (ordinary) visibility.
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- Inoue, S., et al.
(författare)
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Experimental demonstration of exposure-free imaging and contrast amplification
- 2000
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Ingår i: Journal of Optics B-Quantum and Semiclassical Optics. - : IOP Publishing. - 1464-4266 .- 1741-3575. ; 2:3, s. 338-345
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Tidskriftsartikel (refereegranskat)abstract
- Interference between waves can yield quite counterintuitive results. Some time ago, Elizur and Vaidman (1993 Found. Phys. 23 987) proposed a way to detect the presence or absence of a perfectly absorbing object by probing it with light, without any photons being absorbed. Here we present experimental results where a photographic film's shape is imaged on an identical piece of film without exposing the first film. This is possible by using resonant imaging, i.e. by holding the film to be imaged inside an optical resonator. Using the same technique, it is also possible to image nearly transparent objects. The resonant imaging will 'amplify' small transmission variations rendering the nearly invisible clearly visible.
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- Mikheev, A M, et al.
(författare)
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Frequent activation of CArG binding factor-A expression and binding in N-methyl-N-nitrosourea-induced rat mammary carcinomas
- 2004
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Ingår i: Breast Cancer Research and Treatment. - : Springer Science and Business Media LLC. - 1573-7217 .- 0167-6806. ; 88:1, s. 95-102
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Tidskriftsartikel (refereegranskat)abstract
- We previously identified a positive transcriptional element identical to human Ha-ras response element ( HRE) within the promoter of the rat Ha-ras gene. We further identified CArG binding factor A ( CBF-A), a member of heterogeneous nuclear ribonuclear protein ( hnRNP) gene family, as a trans-acting factor that binds the HRE sequence with high affinity in rat mammary carcinoma cells. To determine if activation of CBF-A plays a role in tumor development in vivo, we investigated CBF-A expression and binding activity in rat mammary tumors induced by N-methyl-N-nitrosourea. We found that -82% of tumors expressed CBFA at levels that were 3-20 fold higher than detected in normal mammary gland. Moreover, elevated CBF-A protein levels were invariably associated with increased binding activity to the HRE. CBF-A mRNA levels in tumors were on average elevated only two fold as compared to normal mammary gland, indicating that increased CBF-A protein levels in tumors resulted from both translational and/or post-translational regulation. The level of CBF-A expression in mammary tumors was independent of Ha-ras mutational status. Together, these findings indicated that deregulation of CBF-A contributes to mammary carcinogenesis via a mechanism that is distinct from its hnRNP functions in binding and post-transcriptional regulation of RNA.
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- Soderholm, J., et al.
(författare)
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Quantum limits on phase-shift detection using multimode interferometers
- 2003
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 67:5
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Tidskriftsartikel (refereegranskat)abstract
- Fundamental phase-shift detection properties of optical multimode interferometers are analyzed. Limits on perfectly distinguishable phase shifts are derived for general quantum states of a given average energy. These bounds are found to be independent of the number of interfering modes, and are consistent with the Heisenberg limit. A short discussion on the concept of well-defined relative phase is also included.
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