https://doi.org/10.1140/epjqt/s40507-024-00249-7
Research
Synthesis of robust memory modes for linear quantum systems with unknown inputs
1
School of Mechanical Engineering and Automation, and Guangdong Key Laboratory of Intelligent Morphing Mechanisms and Adaptive Robotics, Harbin Institute of Technology, 518055, Shenzhen, China
2
State Key Laboratory of Industrial Control Technology, and Institute of Cyber-Systems and Control, College of Control Science and Engineering, Zhejiang University, 310027, Hangzhou, China
3
School of Automation Science and Electrical Engineering, and Beijing Advanced Innovation Center for Big Data and Brain Computing, Beihang University, 100191, Beijing, China
a
miaozibo@hit.edu.cn
c
ypan@zju.edu.cn
Received:
8
August
2023
Accepted:
19
May
2024
Published online:
30
May
2024
In this paper, the synthesis of robust memory modes for linear quantum passive systems in the presence of unknown inputs has been studied, aimed at facilitating secure storage and communication of quantum information. In particular, we can switch on decoherence-free (DF) modes in the storage stage by placing the poles on the imaginary axis via a coherent feedback control scheme, and these memory modes can further be simultaneously made robust against perturbations to the system parameters by minimizing the condition number associated with imaginary poles. The DF modes can also be switched off by tuning the controller parameters to place the poles in the left half of the complex plane in the writing/reading stage. We develop explicit algebraic conditions guiding the design of such a coherent quantum controller, which involves employing an augmented system model to counter the influence of unknown inputs. Examples are provided to illustrate the procedure of synthesizing robust memory modes for linear optical quantum systems.
Key words: Linear quantum passive systems / Unknown inputs / Robust memory modes
© The Author(s) 2024
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