Continuous variable surface codes: hearing a whisper in the quantum noise - Gavin Brennen

Over the past decade there has been a convergence in the fields of condensed matter and quantum information with the discovery that many body phases of matter can used for storing and processing quantum data. The best known example of this is the qubit toric code but to date only small sized systems can be prepared in the lab. I will describe a bosonic continuous variable version of the toric code that can be prepared in large scale frequency or temporal modes of light using current technology. Such states are topologically ordered and remarkably the topological entanglement entropy can be efficiently measured in the laboratory [1]. Furthermore, these states can be used as a resource for anonymous broadcasting of classical information amoung many parties. High squeezing enables large transmission bandwidth and strong anonymity, and the topological nature of the state enables local error mitigation [2]. [1] T. Demarie, T. Linjordet, N. Menicucci, and G.K. Brennen, "Detecting Topological Entanglement Entropy in a Lattice of Quantum Harmonic Oscillators," New Journal of Physics 16, 085011 (2014). [2] N. Menicucci, T. Demarie, and G.K. Brennen, "Anonymous broadcasting with a continuous variable topological quantum code," arXiv:1503.00717.