## On noise in swap ASAP repeater chains: exact analytics, distributions and tight approximations

### – 11/07 – 12:00pm – HBL Instruction 1102 –

**Abstract: **Losses are one of the main bottlenecks for the distribution of entanglement in quantum networks, which can be overcome by the implementation of quantum repeaters. The most basic form of a quantum repeater chain is the swap ASAP repeater chain. In such a repeater chain, elementary links are generated and swapped as soon as two adjacent links have been generated. As each entangled state is waiting to be swapped, decoherence is experienced, lowering the fidelity of the state. The aim of this project is to understand the total amount of decoherence experienced. We find analytical expressions for the average noise and its distribution for a small number of links. Furthermore, by exploiting tools from analytic combinatorics we find exponentially tight approximations on the average noise. Finally, we also use methods from statistical physics to numerically calculate quantities of interest for the inhomogeneous case. Our tools can be used to understand and optimize the performance of near-term quantum communication systems.

**Bio:** Dr. Kenneth Goodenough is a postdoctoral researcher under Don Towsley at the University of Massachusetts, Amherst. During his PhD with David Elkouss at QuTech he has worked on near-term repeater schemes, and afterwards focused on distillation and error correction. Currently he is interested in understanding the mathematical structures behind noisy quantum systems.