News and views (3&4)

The foundational work of Clarke, Devoret, and Martinis established macroscopic quantum tunneling and energy level quantization in Josephson junctions made of conventional metal superconductors.This commentary examines the fundamental parameters that determine the temperature for realizing those quantum phenomena.Elevating this temperature may promise superconducting quantum computation in a helium-4 cryostat, instead of the more sophisticated dilution refrigerator system that is being widely used today.We discuss the benefits and challenges of using high-temperature superconductors.We suggest that van der Waals stacking of twisted cuprates offers a promising path toward tunable and electromagnetically isolated high-temperature Josephson junctions for hosting macroscopic quantum coherence at unprecedentedly high temperatures.