## Abstract

Quantum amplifier is an essential device in quantum information processing. As in the classical (non-quantum) case, its characteristic uncertainty needs to be suppressed by feedback, and in fact such a control theory for a single quantum amplifier has recently been developed. This letter extends this result to the case of cascaded quantum amplifier. In particular, we consider two types of structures: the case where controlled amplifiers are connected in series, and the case where a single feedback control is applied to the cascaded amplifier. Then, we prove that the latter is better in the sense of sensitivity to the uncertainty. A detailed numerical simulation is given to show actual performance of these two feedback schemes.

Original language | English |
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Article number | 8424461 |

Pages (from-to) | 156-161 |

Number of pages | 6 |

Journal | IEEE Control Systems Letters |

Volume | 3 |

Issue number | 1 |

DOIs | |

Publication status | Published - 2019 Jan |

## Keywords

- Quantum information and control
- robust control
- stability of linear systems

## ASJC Scopus subject areas

- Control and Systems Engineering
- Control and Optimization