Next Wednesday the Centre for Quantum Technologies is putting on a show:

• The Famous, the Bit and the Quantum, CQT Annual Symposium 2011, Centre for Quantum Technologies, Singapore, 7 December 2011.

There will be three talks. Since I’m not famous, I must either the ‘bit’ or the ‘quantum’. (Seriously, I have no idea what the title of this workshop means.)

• 3 pm. Immanuel Bloch (Max-Planck-Institut für Quantenoptik): **Controlling and exploring quantum gases at the single atom level**.

Abstract:Over the past years, ultracold quantum gases in optical lattices have offered remarkable opportunities to investigate static and dynamic properties of strongly correlated bosonic or fermionic quantum many-body systems. In this talk I will show how it has recently not only become possible to image such quantum gases with single atom sensitivity and single site resolution, but also how it is now possible to coherently control single atoms on individual lattice sites, how one can measure hidden order parameters and how one can follow the propagation of entangled quasiparticles in a many-body setting. In addition I will present recent results on the generation of strong effective magnetic fields for ultracold atoms in optical lattices, which has opened a new avenue for realizing fractional quantum Hall like states with atomic gases.

• 4.30 pm. Harry Buhrman (Centrum Wiskunde & Informatica & University of Amsterdam): **Position-based cryptography**.

Abstract:Position-based cryptography uses the geographic position of a party as its sole credential. Normally digital keys or biometric features are used. A central building block in position-based cryptography is that of position-verification. The goal is to prove to a set of verifier that one is at a certain geographical location. Protocols typically assume that messages can not travel faster than the speed of light. By responding to a verier in a timely manner one can guarantee that one is within a certain distance of that verifier. Quite recently it was shown that position-verification protocols only based on this relativistic principle can be broken by two attackers who simulate being at a the claimed position while physically residing elsewhere in space. Because of the no-cloning property of quantum information (qubits) it was believed that with the use of quantum messages one could devise protocols that were resistant to such collaborative attacks. Several schemes were proposed that later turned out to be insecure. Finally it was shown that also in the quantum case no unconditionally secure scheme is possible. We will review the field of position-based quantum cryptography and highlight some of the research currently going on in order to develop, using reasonable assumptions on the capabilities of the attackers, protocols that are secure in practice.

• 6 pm. John Baez (U.C. Riverside & CQT): **Probabilities versus amplitudes**.

Abstract:Some ideas from quantum theory are just beginning to percolate back to classical probability theory. For example, there is a widely used and successful theory of “chemical reaction networks”, which describes the interactions of molecules in a stochastic rather than quantum way. If we look at it from the perspective of quantum theory, this turns out to involve creation and annihilation operators, coherent states and other well-known ideas•but with a few big differences. The stochastic analogue of quantum field theory is also used in population biology, and here the connection is well-known. But what does it mean to treat wolves as fermions or bosons?

People who have been following my network theory course will know this stuff already. I’ll give a more detailed mini-course on network theory here:

• Expository Quantum Lecture Series 5 (EQuaLS5), Institute for Mathematical Research (INSPEM), Universiti Putra Malaysia, Malaysia, 9-13 January 2012.

This looks like fun because a number of people will be giving such mini-courses:

• Do Ngoc Diep (Inst of Math, Hanoi): **A procedure for quantization of fields**.

• Maurice de Gosson (Univ. of Vienna): **The symplectic camel and quantum mechanics**.

• Fredrik Stroemberg (Technical Univ. of Darmstadt): **Arithmetic quantum chaos**.

• S. Twareque Ali (Concordia University, Montreal): **Coherent states: theory and applications**.

The ‘symplectic camel’, in case you’re wondering, is an allusion to Mikhail Gromov’s result on classical mechanics limiting our ability to squeeze a region of phase space into a long and skinny shape. It’s like trying to squeeze a camel through the eye of a needle!

Later, I’ll give a version of my talk ‘Probabilities versus amplitudes’ at this workshop:

• Coogee ’12: Sydney Quantum Information Theory Workshop, Coogee Bay Hotel, Australia, 30 January – 2 February 2012.

The workshop will focus on quantum computation with spin lattices, quantum memory, and quantum error correction. The speakers include:

• Sean Barrett (Imperial College London, UK)

• Hector Bombin (Perimeter Institute, Canada)

• Andrew Doherty (Sydney, Australia)

• Guillaume Duclos-Cianci (Sherbrooke, Canada)

• Steve Flammia (Caltech/Washington, USA)

• Jeongwan Haah (Caltech, USA)

• Robert Koenig (IBM, USA)

• Tobias Osborne (Leibniz Universitat Hannover, Germany)

• David Poulin (Sherbrooke, Canada)

• Jiannis Pachos (Leeds, UK)

• Norbert Schuch (Caltech, USA)

• Frank Verstraete (Vienna, Austria)

• Guifre Vidal (Perimeter Institute, Canada)

I’d better stop blogging and get my talk ready!