# Multiphoton processes by conditional measurements in the atom-field interaction

## TL;DR

This paper demonstrates how conditional measurements on a two-level atom interacting with a cavity field can induce multiphoton addition or subtraction, enabling control over the photon number in the cavity.

## Contribution

It introduces a method to add or remove multiple photons from a cavity field via entanglement and measurement of a two-level atom, expanding quantum control techniques.

## Key findings

- Multiphoton addition and subtraction are achievable through conditional measurements.
- Entanglement between atom and field enables control of photon number.
- The process allows for manipulating cavity fields beyond single-photon transitions.

## Abstract

We show that it is possible to add or subtract many photons from a cavity field by interacting it resonantly with a two-level atom. The atom, after entangling with the field inside the cavity and exiting it, may be measured in one of the Schmidt states, producing a multiphoton process (in the sense that can add or annihilate more photons than a single transition allows), i.e., adding or subtracting several photons from the cavity field.