biostudies-literatureUnknown644(8078)Aigner ATunability in active metasurfaces has mainly relied on shifting the resonance wavelength^1,2 or increasing material losses^3,4 to spectrally detune or quench resonant modes, respectively. However, both methods face fundamental limitations, such as a limited Q factor and near-field enhancement control and the inability to achieve resonance on-off switching by completely coupling and decoupling the mode from the far field. Here we demonstrate temporal symmetry breaking in metasurfaces through ultrafast optical pumping, providing an experimental realization of radiative-loss-driven resonance tuning, allowing resonance creation, annihilation, broadening and sharpening. To enable this temporal control, we introduce restored symmetry-protected bound states in the continuum. ENature896-902https://www.ebi.ac.uk/biostudies/studies/S-EPMC12390841biostudies-literatureOptical control of resonances in temporally symmetry-broken metasurfaces.PMC12390841Antonov AAAigner AWeber TTittl AMaier SAPossmayer Tde S Menezes LfalseOptical control of resonances in temporally symmetry-broken metasurfaces.Tunability in active metasurfaces has mainly relied on shifting the resonance wavelength^1,2 or increasing material losses^3,4 to spectrally detune or quench resonant modes, respectively. However, both methods face fundamental limitations, such as a limited Q factor and near-field enhancement control and the inability to achieve resonance on-off switching by completely coupling and decoupling the mode from the far field. Here we demonstrate temporal symmetry breaking in metasurfaces through ultrafast optical pumping, providing an experimental realization of radiative-loss-driven resonance tuning, allowing resonance creation, annihilation, broadening and sharpening. To enable this temporal control, we introduce restored symmetry-protected bound states in the continuum. E2025-01-01T00:00:00Z2025 Aug2026-05-10T05:01:50.564Z2026-04-08T01:32:04.218ZS-EPMC123908414077010510.1038/s41586-025-09363-7