November 2009 - ITP-quantumseminare

[QI] QI Seminar
by Dejan D. Dukaric 23 Nov '09

23 Nov '09

Dear All, This weeks research day on Tuesday will be at the Computer Science Building. Speaker: Ligong Wang Title: Hypothesis Testing and Channel Capacity Time: 5 pm Place: IFW D42 Abstract: I shall try to demonstrate connections between these two subjects by showing that they use basically the same quantities and proof techniques. Cheers, Dejan

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[QI] QI Seminar
by Dejan D. Dukaric 16 Nov '09

16 Nov '09

Dear All, This weeks research day on Tuesday will be at the Computer Science Building. Speaker: Marco Tomamichel Title: Non-asymptotic quantum information theory with applications Time: 5 pm Place: IFW E44 (as the door will be locked you can call me to open the door: 27433) Abstract: I will discuss the need for a non-asymptotic quantum information theory using the example of quantum cryptography. Two non-asymptotic measures of conditional entropy, the smooth min- and max-entropies, are introduced. I will explore some of their properties, including a duality relation that illustrates their quantum character. Finally, the connection to asymptotic (Shannon) information theory is established via a fully quantum generalization of the asymptotic equipartition property. Cheers, Dejan

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[QI] QI Seminar
by Dejan D. Dukaric 06 Nov '09

06 Nov '09

Dear All, Next weeks research day on Tuesday will be at the Physics Building. Christian will present his Master Thesis he wrote in Jürg Fröhlich's group. Speaker: Christian Schilling Title: Indeterminism and Decoherence in Standard Quantum Theory Time: 5 pm Place: HIT K51 Abstract: In the first part we will address the question of indeterminism in standard quantum theory with respect to measurement processes. A priori, it is not clear whether the outcome of a measurement is determined by the initial quantum state of the measurement device. We disprove determinism in that sense by analyzing a correlated two-particle system in an initial spin singlet state and a measurement apparatus, which measures the spin of one of the particles. The second part will investigate decoherence in the double slit experiment for a charged particle caused by an irradiated (monochromatic) laser wave. By calculating the decoherence parameter it will be shown that the laser wave destroys the interference pattern under certain conditions, namely a high laser intensity, long interaction time and a wavelength of the laser in the order of the slit distance. Our results and further quantum features also emphasize the non absoluteness of quantum events. Cheers, Dejan

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research day this week
by Roger Colbeck 01 Nov '09

01 Nov '09

Hi all, I will give this week's talk will in HIT K51 at 5pm on Tuesday. Title and abstract below. Cheers, Roger --- "Boxworld is boring" I will present recent work where we have shown that the allowed reversible dynamics in box-world (a hypothetical theory in which all non-signalling correlations are permitted) are trivial. A corollary of this result is that boxworld is not compatible with "fundamental reversibility" (the ability to see any physical process as a reversible one on a larger space). In other words, a universe with the state space of boxworld must be irreversible, even at the microscopic level. An interesting open question is which theories are fundamentally reversible? The answer to this question may go a long way towards homing in on quantum theory...

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