Zeptojoule calorimetry
Mikko Möttönen
Nature Electronics, Published online: 12 May 2026; doi:10.1038/s41928-026-01615-2 A metallic superconductor–normal-conductor–superconductor sensor can be used to measure the energy of 1-μs-long 8.4-GHz microwave pulses with a full-width at half-maximum energy resolution finer than 0.95 ± 0.02 zJ, corresponding to 170 photons at 8.4 GHz.