What are attosecond light pulses and why did they win the 2023 Nobel Prize?

The answer

The 2023 Nobel Prize in Physics was awarded to Pierre Agostini, Ferenc Krausz, and Anne L'Huillier for developing methods to generate attosecond pulses of light. An attosecond is one quintillionth (10⁻¹⁸) of a second - the timescale at which electrons move within atoms. L'Huillier discovered that laser light interacting with noble gases produces overtone harmonics that can be combined into pulses lasting just hundreds of attoseconds. Agostini produced 250-attosecond pulse trains in 2001, while Krausz isolated single 650-attosecond pulses that same year. These ultrafast flashes allow scientists to directly observe electron dynamics during chemical reactions, potentially revolutionizing semiconductor design, medical diagnostics, and our fundamental understanding of quantum chemistry.