QC Research Seminar: Error-corrected quantum logic gates

Speaker: Ben Brown (IBM).

Abstract: 
In order to scale a quantum computer to solve difficult problems, not only do we need to produce a quantum memory that protect quantum information from noise, but we also need to perform logical operations (logic gates) to manipulate the protected states. Like the memory, these logic gates must also protect their encoded quantum information as gates are performed. A number of the major breakthroughs in the field of error-corrected logic gates have been made through building connections between quantum error-correcting codes and topological phases of matter. Indeed, the surface code is central to this connection, and this model has captured the imagination of the entire error-correction community. In this talk I will explain how error-corrected logic is performed with the surface code by introducing lattice dislocations with behaviour that is analogous to anyonic quasiparticle excitations known as Majorana fermions. I will also explain how we can use transformations between different topological phases of matter via gauging operations to create magic states; an essential component in a logic gate set. I will mention experimental progress towards the realisations of these gates, and I will look ahead to describe how these ideas are being adapted for quantum computing architectures with long-range interactions, that can potentially minimise the high resource cost of building a practical quantum computer.