### Abstract

A Free Electron Laser (FEL) operating in the quantum regime can provide a compact and monochromatic Xray source. Here we review the basic principles of a high-gain quantum FEL starting from noise, with special emphasis on the self-amplified spontaneous emission (SASE) mode of operation. In the first part of the paper, a condition for the neglect of the fermionic character of the electrons is derived and the full quantum theory of the N-particle and single-radiation-mode FEL Hamiltonian is presented. Quantum effects such as cooperative gain, discrete spectrum and line narrowing are described, both in the multi-particle and in the second quantization formalism. In the second part, propagation effects (i.e. slippage) are described and the main features of the quantum SASE regime are discussed. The broad and spiky radiation spectrum observed in classical SASE reduces in the quantum regime to a series of narrow lines, associated with sequential transitions between adjacent momentum states. A simple interpretation of the discrete nature of the spectrum and of the linewidth of the single spike observed in the quantum regime is presented.

Language | English |
---|---|

Pages | 1041-1051 |

Number of pages | 11 |

Journal | Progress of Physics |

Volume | 57 |

Issue number | 11-12 |

Early online date | 13 Oct 2009 |

DOIs | |

Publication status | Published - Nov 2009 |

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### Keywords

- monochromatic X-ray
- discrete spectrum
- cooperative gain
- line narrowing
- self-amplified spontaneous emission
- SASE
- propagation effects

### Cite this

*Progress of Physics*,

*57*(11-12), 1041-1051. https://doi.org/10.1002/prop.200900097

}

*Progress of Physics*, vol. 57, no. 11-12, pp. 1041-1051. https://doi.org/10.1002/prop.200900097

**The quantum free electron laser: A new source of coherent, short-wavelength radiation.** / Bonifacio, R.; Piovella, N.; Robb, G. R. M.

Research output: Contribution to journal › Article

TY - JOUR

T1 - The quantum free electron laser: A new source of coherent, short-wavelength radiation

AU - Bonifacio, R.

AU - Piovella, N.

AU - Robb, G. R. M.

PY - 2009/11

Y1 - 2009/11

N2 - A Free Electron Laser (FEL) operating in the quantum regime can provide a compact and monochromatic Xray source. Here we review the basic principles of a high-gain quantum FEL starting from noise, with special emphasis on the self-amplified spontaneous emission (SASE) mode of operation. In the first part of the paper, a condition for the neglect of the fermionic character of the electrons is derived and the full quantum theory of the N-particle and single-radiation-mode FEL Hamiltonian is presented. Quantum effects such as cooperative gain, discrete spectrum and line narrowing are described, both in the multi-particle and in the second quantization formalism. In the second part, propagation effects (i.e. slippage) are described and the main features of the quantum SASE regime are discussed. The broad and spiky radiation spectrum observed in classical SASE reduces in the quantum regime to a series of narrow lines, associated with sequential transitions between adjacent momentum states. A simple interpretation of the discrete nature of the spectrum and of the linewidth of the single spike observed in the quantum regime is presented.

AB - A Free Electron Laser (FEL) operating in the quantum regime can provide a compact and monochromatic Xray source. Here we review the basic principles of a high-gain quantum FEL starting from noise, with special emphasis on the self-amplified spontaneous emission (SASE) mode of operation. In the first part of the paper, a condition for the neglect of the fermionic character of the electrons is derived and the full quantum theory of the N-particle and single-radiation-mode FEL Hamiltonian is presented. Quantum effects such as cooperative gain, discrete spectrum and line narrowing are described, both in the multi-particle and in the second quantization formalism. In the second part, propagation effects (i.e. slippage) are described and the main features of the quantum SASE regime are discussed. The broad and spiky radiation spectrum observed in classical SASE reduces in the quantum regime to a series of narrow lines, associated with sequential transitions between adjacent momentum states. A simple interpretation of the discrete nature of the spectrum and of the linewidth of the single spike observed in the quantum regime is presented.

KW - monochromatic X-ray

KW - discrete spectrum

KW - cooperative gain

KW - line narrowing

KW - self-amplified spontaneous emission

KW - SASE

KW - propagation effects

U2 - 10.1002/prop.200900097

DO - 10.1002/prop.200900097

M3 - Article

VL - 57

SP - 1041

EP - 1051

JO - Progress of Physics

T2 - Progress of Physics

JF - Progress of Physics

SN - 0015-8208

IS - 11-12

ER -