Stabilizing quantum dynamics through coupling to a quantized environment

Presenting Author: Meenu Kumari, University of Waterloo
Contributing Author(s): Shohini Ghose, Eduardo Martin-Martinez, Achim Kempf

Quantum systems can be very sensitive to perturbations such as changes to external control parameters. Past studies on fidelity decay and, in particular, studies related to quantum chaos, have shown that such perturbations can lead to a significant decrease in the fidelity of the quantum system. We present a method to stabilize quantum systems against such perturbations in the sense that a finite lower bound to the fidelity decay can be ensured. To this end, we show that it is possible to improve the fidelity of quantum systems against perturbations to the external control parameters by implementing the external control parameters through the coupling with a quantum ancilla, or environment, that is in a state with suitable uncertainties. We illustrate the method in the model of the quantum kicked top. The new method is applicable to any system, including highly fragile chaotic systems. We illustrate that the effective evolution of the system is characterized by a channel which is non-Markovian. We illustrate that non-Markovianity is important for attaining the desired robustness in the fidelity. The new method should be implementable in experiments.

Read this article online: https://arxiv.org/abs/1711.07906

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