I would like to know what the "0-ket", called vacuum state and used in the following expression, represents $$\Psi(x,t) = \int d^3x <x| \ a^{\dagger}(x) \ |0>$$ I have rewritten the expression for the case of just one ##x##. The expression above is usually presented with ##(x_1,...x_n)## (n particles), in which case we have to integrate over each ##x_i##.(adsbygoogle = window.adsbygoogle || []).push({});

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# I Expression for state function

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