# Fieldoscopy at the quantum limit

## TL;DR

This paper introduces a new method to measure electric fields of single photons with extreme sensitivity and precision, enabling new quantum technologies.

## Contribution

A novel technique for measuring petahertz-scale electric field transients at the single-photon level with yoctojoule sensitivity.

## Key findings

- Observed a classical regime breakdown consistent with Monte Carlo simulations.
- Achieved yoctojoule-level sensitivity and over 90 dB dynamic range.
- Measured intrapulse light coherence inaccessible to traditional spectroscopy.

## Abstract

We demonstrate a novel concept for measuring time-varying electric field transients of petahertz-scale photons down to a single-photon regime. We observe a clear breakdown of the classical regime consistent with our Monte Carlo model. We reach unprecedented yoctojoule-level (10⁻²⁴ J) sensitivity and a dynamic range exceeding 90 decibels. We utilize this capability to measure intrapulse light coherence - a regime inaccessible to conventional, time-averaged spectroscopy. This opens new avenues for quantum information, cryptography, and quantum light-matter interactions on sub-cycle time scales with attosecond precision.