The pub lecture is back!

This time the pub will be bigger ( = more comfortable), but the idea is the same: join a lecture, while enjoying a drink.

The talks will be in English! 

20.00-20.45: Talk by Dirk Schuricht: Collective phenomena in the quantum world

A single football fan raising his arms is not very spectacular, however, if 50,000 do so in an organised way it becomes impressive. This is an example of a collective phenomenon; loosely speaking many things together can bring about behaviour impossible for the individual. In this presentation I will discuss collective phenomena in the quantum world. After recapitulating the basic properties of electrons, I focus on two examples. First, I discuss spin-charge separation, in which the electron is split into two pieces. Second, I present the quantum Hall effect, in which even the fundamental electric charge (and statistics) is cut to pieces.

21.15-22.00: Talk by Lola Thompson: An efficient algorithm for summing values of arithmetic functions

The Moebius function, mu(n), is always equal to ±1 or 0, depending on the prime factorization of the input n. In a recent paper with Harald Helfgott, we devised a new elementary algorithm for summing mu(n) for all integers n in intervals [1,x] in time about O(x^{3/5}). This is the first improvement in the exponent of x for this type of algorithm since 1985. In this talk, we will give a friendly discussion of some of the ideas that go into the proof of our algorithm. We will also discuss some of the computational aspects of the problem. Many of these ideas can be adapted to efficiently sum values of other arithmetic functions.

We hope to see you all there!