They spoke of the hacking-resistant communications networks they are building across China, the sensors they are designing to see through smog and around corners, and the prototype computers that may someday smash the computational power of any existing machine.

All the gear is based on quantum technology — an emerging field that could transform information processing and confer big economic and national-security advantages to countries that dominate it. To the dismay of some scientists and officials in the United States, China’s formidable investment is helping it catch up with Western research in the field and, in a few areas, pull ahead.

Beijing is pouring billions into research and development and is offering Chinese scientists big perks to return home from Western labs. China’s drive has sparked calls for more R&D funding in the United States, and helped trigger concerns in the Trump administration that some types of scientific collaboration with China may be aiding the People’s Liberation Army and hurting U.S. interests.

“The United States must be prepared for a future in which its traditional technological predominance faces new, perhaps unprecedented challenges,” the Center for a New American Security wrote in a recent report about China’s quantum ambitions.