Earlier this month, President Joe Biden banned new investment from the United States in key technology industries – such as advanced semiconductors and quantum computers – that could be used to enhance Beijing’s military capabilities. (Last year, the Biden administration restricted exports of advanced semiconductors and chip-manufacturing equipment to China.) But investors worry that Beijing’s decision to change its growth motor will leave the country facing a prolonged period of economic stagnation. They fear the Chinese economy lacks a growth engine, now that infrastructure and property are no longer driving activity. Indeed, recent data indicate that President Xi Jinping now…