# Generation of optical Fock and W states with single-atom-based bright quantum scissors

## TL;DR

This paper presents a deterministic protocol using single-atom systems to engineer optical quantum states, enabling generation of Fock and W states crucial for quantum communication and computing.

## Contribution

It introduces a multi-step, atom-based quantum scissors protocol that can produce advanced optical quantum states deterministically or via heralding.

## Key findings

- Deterministically generates W states of single photons.
- Can produce Fock-state optical pulses with heralding.
- Utilizes single-photon Raman interaction with a single atom.

## Abstract

We introduce a multi-step protocol for optical quantum state engineering that performs as deterministic "bright quantum scissors" (BQS), namely truncates an arbitrary input quantum state to have at least a certain number of photons. The protocol exploits single-photon pulses and is based on the effect of single-photon Raman interaction, which is implemented with a single three-level $\Lambda$ system (e.g. a single atom) Purcell-enhanced by a single-sided cavity. A single step of the protocol realises the inverse of the bosonic annihilation operator. Multiple iterations of the protocol can be used to deterministically generate a chain of single-photons in a W state. Alternatively, upon appropriate heralding, the protocol can be used to generate Fock-state optical pulses. This protocol could serve as a useful and versatile building block for the generation of advanced optical quantum states that are vital for quantum communication, distributed quantum information processing, and all-optical quantum computing.