A Time evolution of coherent state with vacuum

deepalakshmi
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Here I am having a Hamiltonian as a†b + b†a and I want to evolve |0,α⟩ with e^(−iHt)
I have attached my work here. I don't know how to proceed further?
 

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deepalakshmi said:
Summary:: Here I am having a Hamiltonian as a†b + b†a and I want to evolve |0,α⟩ with e^(−iHt)

I have attached my work here.
Attachments are not allowed. Please post your equations directly in the thread using the PF LaTeX feature. You will see a LaTeX Guide link at the bottom left of the post window.
 
The initial state is
##|ψ(0)⟩ = |0⟩ |α⟩##
The time evolved state is
##|ψ(t)⟩ = e^(−iHt) |0⟩|α⟩##
##|ψ(t)⟩ = e^(−iHt) e^(αa†−α∗a) |0⟩|0⟩##
##|ψ(t)⟩ = e^(−iHt) e^(αa†−α∗a)e^(−iHt) e^(iHt) |0⟩|0⟩##
##|ψ(t)⟩ = e^(−iHt) e^(αa†−α∗a)e^(iHt) |0⟩|0⟩##
Using BCH formula
##|ψ(t)⟩ = {e^(αa†−α∗a)+(-it)[ b†a+a†b, e^(αa†−α∗a)]+(it)^2{\2}[b†a+a†b,[b†a+a†b, e^(αa†−α∗a)]]+...}|0⟩|0⟩##
##|ψ(t)⟩={e^(αa†−α∗a)+(-it)((e^(αa†−α∗a) αb†+α∗b)+(it)^2{\2}((αa†−α∗a)+(αb†+α∗b)^2)e^(αa†−α∗a)+...}|0⟩|0⟩##
How to simplify further?
 
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