Challenges in Building Fault-Tolerant Quantum Computers

There are several challenges in building fault-tolerant quantum computers. Firstly, the need for higher quality qubits is a significant obstacle. While it is easier to build qubits today, constructing higher quality qubits remains incredibly difficult. Secondly, there is a requirement for a physical infrastructure that allows for on-the-fly classical logic integration with qubits, essential for quantum error correction. This necessitates very fast computing capabilities to decode and correct errors in parallel with quantum computation. Lastly, the challenge lies in creating scalable architectures and manufacturing capabilities. The ability to build millions or billions of chips at high scale is crucial, highlighting the massive scale of the computing industry. Currently, no quantum modality satisfactorily addresses all of these challenges.