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I have a query: Let us  have 2 particles and 2 corresponding wavefunctions, under two incompatible Hamiltonians ( $H_1,H_2$).

$$\Psi_1(x_1,t_1)= e^{-x_1} e^{i\sin(\pi t_1/3)}+e^{-x_1^2}e^{i\cos(\pi t_1/5)}$$ and $$\Psi_2(x_2,t_2)= e^{-x_2}e^{i\cos(\pi t_2/12)} +e^{-x_2^2}e^{i\sin(3\pi t_2/20)}$$ These are such that they become the same expression at $t_1= 1\,\text s$ and $t_2=2\,\text s$ respectively.

Now, after $t_1=1\, \text s$ , if we act the Hamiltonian $H_2$ on particle 1 , what can we expect to happen?

SX849
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1 Answers1

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The comments clarified your question a bit.

This question has nothing to do with entanglement.

  • A two particle wave function is $\Psi(x_1,x_2,t)$. None of your function is of that form. They are one particle wave functions.

  • The two particle wave function describes entangled particles when it cannot be written in the form $$ \Psi(x_1,x_2,t)=\Psi_1(x_1,t)\Psi_2(x_2,t)\,. $$

To the idea you had with your question: It is conceivable that you can smoothly paste together "two" wave functions $\Psi_1(x,t)$ and $\Psi_2(x,t)$ at some fixed $t$ but this will still give a single particle wave function because its space argument is one dimensional.

If you like here is my first version of the answer:

Doing calculations such as

\begin{align} \frac{\partial\Psi_1}{\partial t_1}&=e^{-x_1}e^{i\sin(\pi t_1/3)}\cos(\pi t_1/3)\frac{i\pi}{3}-e^{-x_1^2}e^{i\cos(\pi t_1/5)}\sin(\pi t_1/5)\frac{i\pi}{5}\,,\\ \frac{\partial\Psi_1}{\partial x_1}&=-e^{-x_1}e^{i\sin(\pi t_1/3)}-2x_1e^{-x_1^2}e^{i\cos(\pi t_1/5)}\,,\\ \frac{\partial^2\Psi_1}{\partial x_1^2}&=e^{-x_1}e^{i\sin(\pi t_1/3)}-2e^{-x_1^2}e^{i\cos(\pi t_1/5)}+4x_1^2e^{-x_1^2}e^{i\cos(\pi t_1/5)}\,,\\ \end{align} -and same for $\Psi_2$- one should be able to write down the Hamiltonians $H_1,H_2$ explicitly so that each $\Psi_1$ and $\Psi_2$ satisfies the Schrödinger equation $$ i\hbar\frac{\partial \Psi_i}{\partial t_i}=H_i\Psi_i\,. $$ Regarding your question what happens when we act $H_2$ on $\Psi_1\,:$ It is unlikely that $$ i\hbar\frac{\partial \Psi_1}{\partial t_1}=H_2\Psi_i $$ holds. In other words, it is unlikely that $H_2$ is the energy operator of "particle 1". The fact that $\Psi_1(\,.,t_1)$ and $\Psi_2(\,.,t_2)$ agree for two $t_1$ and $t_2$ is obviously totally irrelevant because the time evolution of $\Psi_1$ is governed by $H_1$ and not by $H_2\,.$

Kurt G.
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