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"Quantum Measurement Theory" (9. September 2013)

Opening day of the Workshop on "Incompatible Quantum Measurements"

Poster for download

One of the fundamental and most striking implications of quantum mechanics, and a stark contrast to classical physics, is the existence of incompatible experimental setups. As originally found by Heisenberg, the measurements of position and of momentum of a quantum particle cannot be performed simultaneously without introducing imprecisions. The fact that these quantities are not experimentally compatible reflects the very properties of the quantum theory.

The Day on "Quantum Measurement Theory" is held on 9. September 2013 in Garching Forschungszentrum, and will feature three researchers in the field to give an overview and introduction to this area. The talks are expected to be interesting and understandable for anybody having some familiarity with quantum mechnics. Everybody interested is welcome to attend. No prior registration required.

Program and Speakers

Location: Hörsaal 2, Mathematics/Informatics Building, Garching Campus of TU München
Boltzmannstr. 3, 85748 Garching

13:45 Prof. Michael Wolf (TUM)
Welcome and Opening

14:00 Robert W. Spekkens (Perimeter Institute for Theoretical Physics, Canada)
"Unscrambling the omelette: distinguishing reality from information in quantum theory"

E.T. Jaynes famously remarked of the standard quantum formalism that "it is a peculiar mixture describing in part realities of Nature, in part incomplete human information about Nature - all scrambled up by Heisenberg and Bohr into an omelette that nobody has seen how to unscramble." This talk will review some recent efforts to unscramble Jaynes's omelette. The first effort is a bottom-up approach. It considers theories that are essentially classical but where there is a fundamental restriction on how much knowledge can be acquired about the physical state of any system. Such theories can reproduce a surprisingly large part of quantum theory. The second approach is top-down and argues that the formalism of quantum theory is naturally interpreted as a noncommutative generalization of the theory of Bayesian inference, with quantum states summarizing an agent's degrees of belief. After identifying all the aspects of the formalism that are about knowledge or inference, what remains can be safely identified as containing the physics. In particular, it will be argued that a unitary is a feature of reality, as is a subtle distinction between spatial relations and temporal relations in quantum theory.

15:00 Coffee Break

15:30 Teiko Heinosaari (Department of Physics and Astronomy, University of Turku, Finland) - QCCC speaker
"Quantum Incompatibility"

Two things are often called incompatible if they are not consistent with each other, for instance, a flat-head screwdriver is incompatible with a hex socket screw. In the context of a physical theory, two things, A and B, described by the theory are called incompatible if the theory does not allow for the existence of a third thing C that would have both A and B as its components. Incompatibility is a fascinating aspect of many physical theories, especially in the case of quantum theory. The concept of incompatibility gives a common ground for several famous impossibility statements within quantum theory, such as 'no-cloning' and 'no information without disturbance'; these can be all seen as statements about incompatibility of certain devices. This talk develops the incompatibility point of view in quantum theory, giving several examples on the nature of this concept. It will be argued that incompatibility should be seen as resource rather than a hindrance.

16:30 Coffee Break

17:00 Paul Busch (Department of Mathematics, University of York, UK)
"Heisenberg Uncertainty for Joint Measurements"

The Uncertainty Principle, conceived by W. Heisenberg in 1927, epitomises the fundamental philosophical implications of quantum mechanics and its radical departure from classical physics. For decades, there has been an air of vagueness and perhaps even mystique around its formulation and interpretation, which may have contributed to the media hype in 2012 when it was announced that the principle had been experimentally violated. In this lecture I survey precise formulations of Heisenberg's principle as trade-off relation for measurement errors and disturbance due to measurement. Recent claims about experimental refutations of the principle are shown to be untenable and found to have arisen from the unwarranted extrapolation of classical physical intuitions about measurement inaccuracies and measures of disturbance.

18:00 End


The talks will take place in Hörsaal 2 in the Mathematics/Informatics Building of the TU München (Garching campus, metro stop "Garching-Forschungszentrum" U6, Boltzmannstr. 3, 85748 Garching). Directions

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Organization and Contact

This event is supported by