K. Vogel and H. Risken, "Determination of Quasiprobability Distributions in Terms of Probability Distributions for the Rotated Quadrature Phase," Phys. Rev. A 40, 2847 (1989); U. Leonhardt, "Quantum-State Tomography and Discrete Wigner Function," Phys. Rev. Lett. 74, 4101 (1995).  Home/Search   Document Not in Database   Summary   APS   Related Articles   Check

....it would be quite contrived to imagine that there is always someone in the background describing the system being measured or manipulated, and that what we are doing is grounding the phenomenon with respect to his state of belief. The solution, at least in the case of quantum state tomography [31], is found through a quantum mechanical version of de Finetti s classic theorem on unknown probabilities. This reports work from Refs. 32] and [33] Maybe one of the most interesting things about the theorem is that it fails for Hilbert spaces over the field of real numbers, suggesting that ....

....single quantum state used for describing the phenomenon namely, the state that actually captures the describer s overall set of beliefs throughout. This Section reports the work of Ref. 32] and [33] where such a project is carried out for the experimental practice of quantum state tomography [31]. The usual description of tomography is this. A device of some sort, say a nonlinear optical medium driven by a laser, repeatedly prepares many instances of a quantum system, say many temporally distinct modes of the electromagnetic field, in a fixed quantum state #, pure or mixed [103] An ....

K. Vogel and H. Risken, "Determination of Quasiprobability Distributions in Terms of Probability Distributions for the Rotated Quadrature Phase," Phys. Rev. A 40, 2847 (1989); U. Leonhardt, "Quantum-State Tomography and Discrete Wigner Function," Phys. Rev. Lett. 74, 4101 (1995).

....or quaternionic ones [24 27] Furthermore, the method we use to prove our main theorem employs a novel measurement technique that might be of use in the laboratory. We analyze in depth a particular use of unknown states, which comes from the measurement technique known as quantum state tomography [28 30]. The usual description of tomography is this. A device of some sort, say a nonlinear optical medium driven by a laser, repeatedly prepares many instances of a quantum system, say many temporally distinct modes of the electromagnetic eld, in a xed quantum state , pure or mixed. An ....

K. Vogel and H. Risken, \Determination of Quasiprobability Distributions in Terms of Probability Distributions for the Rotated Quadrature Phase," Phys. Rev. A 40, 2847 (1989).

....it exists at all. On the other hand, for many an application in quantum information, it would be quite a contrivance to imagine there is always someone in the background with extra knowledge of the system being measured or manipulated. The solution, at least in the case of quantum state tomography [13], is found through a quantum mechanical version of de Finetti s classic theorem on unknown probabilities. This reports work from Refs. 17] and [18] Maybe one of the most interesting things about the theorem is that it fails for Hilbert spaces over the field of real numbers, suggesting that ....

....a single quantum state used for describing the phenomenon namely, the state that actually captures the describer s state of knowledge throughout. This Section reports the work of Ref. 17] and [18] where such a project is carried out for the experimental practice of quantum state tomography [13]. The usual description of 33 y y y Figure 2: To make sense of quantum tomography, must we go to the extreme of imagining a man in the box who has a better description of the systems than we do How contrived our usage would be if that were so tomography is this. A device of some sort, ....

K. Vogel and H. Risken, "Determination of Quasiprobability Distributions in Terms of Probability Distributions for the Rotated Quadrature Phase," Phys. Rev. A 40, 2847 (

....output for the teleportation process are always related by a linear quantum operation. By preparing a complete set of four linearly independent initial states, we were able to obtain a complete description of the quantum process. In particular, we used a procedure known as quantum state tomography [181, 169] to determine the output states, and used the linearity of 6 In the language of that Chapter, we determined the dynamic fidelity for teleportation of the state I 2. 2.6. EXPERIMENTAL QUANTUM INFORMATION PROCESSING 39 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 0.0 0.2 0.4 0.6 0.8 1.0 Decoherence ....

K. Vogel and H. Risken. Determination of quasiprobability distributions in terms of probability distributions for the rotated quadrature phase. Phys. Rev. A, 40(12):7113--7120, 1989.

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