There’s a quiet movement behind a new idea for government technology gaining momentum in technocratic pockets of Washington, D.C.: a central bank digital currency, or CBDC. But some Republicans want to block this potentially authoritarian tool from ever becoming a reality.The idea of a CBDC sounds innocuous enough. It would simply be a “digital dollar” issued by the Federal Reserve, America’s central bank. Its supposed benefits include everything from saving trees to reducing administrative costs. But the downsides of a CBDC are p …