Fault-tolerant quantum computation in the 21st century
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.