  Although the current information revolution is still unfolding, the next
industrial revolution is already rearing its head. A second quantum revolution
based on quantum technology will power this new industrial revolution with
quantum computers as its engines. The development of quantum computing will
turn quantum theory into quantum technology, hence release the power of quantum
phenomena, and exponentially accelerate the progress of science and technology.
Building a large-scale quantum computing is at the juncture of science and
engineering. Even if large-scale quantum computers become reality, they cannot
make the conventional computers obsolete soon. Building a large-scale quantum
computer is a daunting complex engineering problem to integrate ultra-low
temperature with room temperature and micro-world with macro-world. We have
built hundreds of physical qubits already but are still working on logical and
topological qubits. Since physical qubits cannot tolerate errors, they cannot
be used to perform long precise calculations to solve practically useful
problems yet.
