PHz-scale nonlinear photoconductive sampling in air

The electric field waveform of a light field can be used to unlock a detailed recording of its interaction with matter, but accessing it requires a measurement with subfemtosecond temporal resolution. We demonstrate nonlinear photoconductive sampling of light fields at optical frequencies in ambient air. The resulting detection method provides broadband electric field measurement in an inexpensive setup using a self-healing medium. A direct comparison is made between detection in air and in quartz, validating the technique up to 0.7 PHz. This provides both a simple route toward field metrology and a new platform for future studies in attosecond physics without the need for complex vacuum setups or sophisticated sample preparation.