L'Huillier uses attosecond sources to study ultrafast dynamics of electrons in atomic and molecular systems. In 2003 her group beat the world record for the shortest laser pulse, lasting 170 attoseconds. These attosecond sources are considered the world's fastest cameras, using extremely short pulses of light to measure electrons as they move or change in energy. L’Huillier's methods for studying and manipulating electrons using light have pioneered the field of attochemistry as they allows the study electronic processes during chemical reactions.