The Department of Physics at Yale University Announces the Hanan Rosenthal Memorial Lecturer
Anton Zeilinger
University of Vienna
Monday, October 23, 2006
4:00 pm in SPL 59
Quantum Measurement A problem becoming a resource
Abstract: Quantum measurement is often regarded as a problem because there is no way to arrive from a quantum superposition at a specific measurement result through unitary evolution alone. It is also often thought that an understanding of the measurement problem is necessary to explain the existence of a unique macroscopic world. Yet, such problems do not arise if one takes the quantum state to represent just our information. In the talk I will discuss some recent experiments on decoherence of macromolecules where the loss of coherent superposition can easily be understood as the flow of information from teh quantum system into the environment. Interestingly, quantum measurement also has become an important resource in quantum information processing. In a one-way quantum computer quantum measurement can provide an effective nonlinearity for realizing non-trivial quantum gates. Furthermore active feed-forward inside a quantum computer, as recentyl demoinstrated experimentally, has been shown to eliminate the probabilistic effect of quantum measurement. Besides opening up the avenue towards photonic quantum computation such experiments might also shed new light on the nature of computation itself.
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