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Matrix product state (MPS) is a pure quantum state of many particles, written in the following form: : where are complex, square matrices of order (this dimension is called local dimension). Indices go over states in the computational basis. For qubits, it is . For qudits (d-level systems), it is . It is particularly useful for dealing with ground states of one-dimensional quantum spin models (e.g. Heisenberg model (quantum)). The parameter is related to entanglement between particles. In particular, if the state is a product state (i.e. not entangled at all), it can be described as a matrix product state with. For states that are translationally symmetric, we can choose: : In general, every state can be written in the MPS form (with growing exponentially with the particle number ''N''). However, MPS are practical when is small – for example, does not depend on the particle number. Except for a small number of specific cases (some mentioned in the section Examples), such thing is not possible. Though, in many cases it serves as a good approximation. MPS decomposition is not unique. Introductions in.〔 and.〔 In the context of finite automata:〔 == Obtaining MPS == One method to obtain MPS is to use Schmidt decomposition times. 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Matrix product state」の詳細全文を読む スポンサード リンク
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