München 2004 – wissenschaftliches Programm
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Q: Quantenoptik und Photonik
Q 45: Quanteninformation IV
Q 45.4: Vortrag
Freitag, 26. März 2004, 12:00–12:15, HS 101
Upper bounds on success probabilities in linear optics quantum gates — •Stefan Scheel1 and Norbert Lütkenhaus2 — 1Quantum Optics and Laser Science, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2BW, UK — 2QIT group, Institut für Theoretische Physik I, Universität Erlangen-Nürnberg, 91058 Erlangen
We develop an abstract way of defining linear-optics networks designed to perform certain quantum gates. We will be mainly concernced with the nonlinear sign shift (NS) gate but it will become obvious that all other gates can be treated in a similar manner. The abstract scheme is extremely well suited for analytical as well as numerical investigations since it does not depend on the number of ancilla modes at all. With that approch we analyse numerically and partially analytically the NS gate and show evidence that indicates that the success probability of that gate does not exceed 1/4. This is to our knowledge the strongest bound to date.