Experimentalists are getting better and better at building qubits, but no matter how hard they try, their qubits will never be perfect. In order to build a large quantum computer, we will almost certainly need to encode the qubits using quantum error-correcting codes and encode the quantum circuits using fault-tolerant protocols. This will eventually allow reliable quantum computation even when the individual components are imperfect. I will review the current state of the art of quantum fault tolerance and discuss progress towards answering the most important questions that will enable large fault-tolerant quantum computers.
- Scientific Series