Talks

In this talk I will propose a new mechanism for thermal dark matter freezeout, termed Co-Decaying Dark Matter. Multi-component dark sectors with degenerate particles and out-of-equilibrium decays can co-decay to obtain the observed relic density. The dark matter density is exponentially depleted through the decay of nearly degenerate particles, rather than from Boltzmann suppression. The relic abundance is set by the dark matter annihilation cross-section, which is predicted to be boosted, and the decay rate of the dark sector particles. Finally, I'll present a simple model that realizes co-decaying dark matter. 

The possibility of observing quantum gravitational phenomena, viewed as remote until not long ago, is increasingly considered to be plausible.  A potentially observable phenomenon is the decay of black holes via a quantum gravitational tunneling akin to standard nuclear decay.  Loop quantum gravity can be used to compute the corresponding lifetime.  This could be much shorter than the Hawking radiation time, rendering the effect astrophysically relevant. Preliminary estimates indicate that centimeter-size primordial black holes should be exploding today and predict impulsive high energy as well as microwave signals tantalizing similar to the Fast Radio Bursts recently observed by the Areceibo and Parkes radio telescopes.  The predicted signal has a characteristic distance/frequency relation which will allow to test the Planck star hypotheses in the near future.

Raussendorf introduced a powerful model of fault tolerant measurement based quantum computation, which can be understood as a layering (or “foliation”) of a multiplicity of Kitaev’s toric code.  I will discuss our generalisation of Raussendorf’s construction to an arbitrary CSS code.  We call this a Foliated Quantum Code.  Decoding this foliated construction is not necessarily straightforward, so I will discuss an example in which we foliate a family of finite-rate quantum turbo codes, and present the results of numerical simulations of the decoder performance.

If I have time, I will discuss some ongoing work (with Gavin Brennan) on relational time applied to topological quantum field theories, in particular, how anyonic systems with essentially trivial dynamics can still exhibit correlations that track “time".