Topological Quantum Computing with and without Majoranas
Note the different location and time for this week's talk, Wednesday, April 18 at noon in 265 West Bridge
Abstract: Topological quantum computing comes in two flavors. The condensed matter approach is to build error-resilient qubits using exotic quasiparticles in topological materials, most prominently Majorana zero modes in topological superconductors. The quantum information approach is to combine many error-prone qubits (e.g., superconducting qubits) to build more robust logical qubits using topological error-correcting codes. Even though the first approach is hardware-based and the second approach is software-based, schemes for quantum computation with Majoranas or with surface codes can be identical. This presents an opportunity to learn about quantum computing with Majoranas, and simultaneously learn about quantum computing with surface codes. I will present a scheme for universal quantum computation with Majoranas, in which Clifford gates are implemented with zero time overhead. For the equivalent surface-code scheme, Majoranas are replaced by corners of surface-code patches (twist defects), and Majorana parity measurements are replaced by lattice surgery. I will also discuss Majorana fermion surface and color codes, i.e., topological codes that can only be implemented with Majorana-based qubits, but not with conventional qubits such as superconducting qubits. This talk is based on two recent papers: arXiv:1709.02318 and arXiv:1801.08143.