In theory, a quantum computer could perform calculations vastly more quickly than today’s conventional computers.

The chipmaker NVIDIA held its annual conference in Silicon Valley this week. Among the major announcements: it chose Boston to be the site of its first-ever research center for quantum computing, opening later this year.

Quantum-computing stocks fell again Friday, extending the previous session’s losses as investors were left disappointed by a Nvidia event aimed at celebrating the technology.The artificial-intelligence chip maker’s Quantum Day was lacking in major announcements and the formerly highflying stocks tumbled.