Authorities in Nebraska on Tuesday morning used the powerful opioid fentanyl to carry out a death sentence, an unprecedented move that came as the state — which just three years ago briefly abolished capital punishment — completed a remarkable reversal and resumed executions for the first time in nearly a generation. Nebraska experienced a series of firsts Tuesday morning: the state’s first execution in 21 years, its first lethal injection and the country’s first death sentence carried out with fentanyl, which has helped drive the opioid epidemic.