本研究の目的は, システム制御理論に基づき量子状態変換のための設計理論を構築することである。対象系に応じて次の成果を得た。(1)多入力多出力線形系について, 完全状態転送の必要十分条件と実行プロトコルを明らかにした。また, この成果を量子光スイッチ設計へ応用した。(2)典型的な無限次元系であるGradient Echo Memory について, 必要な入力波形, 転送精度の離調依存性などを明らかにした。(3)非線形qubit結合系について, 完全状態転送の必要十分条件と実行プロトコルを明らかにした。(4)1入力1出力線形系について, 入力パルス波形の複雑さを軽減するプロトコルを開発した。
The purpose is to develop useful designing methods for quantum state transfer, based on systems and control theory. Depending on the type of systems, the following results have been obtained. (1) For the general multi-input multi-output linear system, the iff condition for the perfect state transfer and the concrete protocol have been clarified. Also an application to designing a quantum optical switch has been given. (2) For the Gradient Echo Memory system (a typical infinite dimensional system) detailed investigations have been examined ; condition for the input pulse shape, performance evaluation depending on the detuning, and so on. (3) For a coupled qubit system (a typical nonlinear system) the iff condition for the perfect state transfer and the concrete protocol have been clarified. (4) For the general single-input single-output linear system, a novel protocol for reducing the complexity of the required input pulse shape has been developed.
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