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I haven't seen much on this topic, but that's probably because - for superpositions of only a few quantum states - it can be done by inspection rather than Mathematica.

Still, I would like to know how to compute the conjugate of a wavefunction, and I am having trouble getting Mathematica to do this.

My wavefunction is:

Ψ = b1*Exp[-I*ω1*t]*ψ1 + b2*Exp[-I*ω1*t]*Exp[-I*ω*t]*ψ2

Which I then try to take the conjugate of:

Simplify[Conjugate[Ψ], t ω1 ω ∈ Reals]

But Mathematica just outputs the following:

E^(I Conjugate[t ω1])Conjugate[b1 ψ1 + b2 E^(-I t ω) ψ2]

Ideally, I'd like it so that it doesn't just say 'Conjugate', and then leave all of the expressions as they were. In texts, you would see complexes denoted by an '*' in superscript. Is there any way to see this also by a Conjugate function in Mathematica?

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  • $\begingroup$ In Mathematica imaginary unit is I not i! $\endgroup$ Commented Mar 19, 2021 at 17:40
  • $\begingroup$ Oh what a rookie error. Thank you - fixed the i's but doesn't affect Mathematica's ability to perform the conjugate sadly. $\endgroup$ Commented Mar 19, 2021 at 17:44
  • $\begingroup$ See my answer, ComplexExpandmight help. $\endgroup$ Commented Mar 19, 2021 at 17:47

1 Answer 1

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Change i to I

Ψ = b1*Exp[-I*ω1*t]*ψ1 + b2*Exp[-I*ω1*t]*Exp[-I*ω*t]*ψ2

Simplify[Conjugate[Ψ],Element[{t, ω1, ω}, Reals]]
(*E^(I t ω1) Conjugate[b1 ψ1 + b2 E^(-I t ω) ψ2]*)

Further Simplification might be achieved with ComplexExpand

ComplexExpand[Conjugate[Ψ]]
(*b1 ψ1 Cos[t ω1] + b2 ψ2 Cos[t ω + t ω1] - 
I (-b1 ψ1 Sin[t ω1] -b2 ψ2 Sin[t ω + t ω1])*)

For complex b1,b2 try

ComplexExpand[Conjugate[Ψ], {b1, b2}]
(*ψ1 (Cos[t ω1] Re[b1] + 
Im[b1] Sin[t ω1]) + ψ2 (Cos[ t ω + t ω1] Re[b2] + Im[b2] Sin[t ω + t ω1]) - 
I (ψ1 (Cos[t ω1] Im[b1] -Re[b1] Sin[t ω1]) + ψ2 (Cos[t ω + t ω1] Im[b2] -Re[b2] Sin[t ω + t ω1]))*)
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    $\begingroup$ Thanks for the info - your first answer is helpful, as it at least gives the [Omega]1 exponential term conjugate. Is there any way that you know of where the conjugates of b1 and b2 can be shown as b1* and b2*, or is this not a Mathematica functionality? $\endgroup$ Commented Mar 19, 2021 at 17:53
  • $\begingroup$ Sorry don't know how to do that. But if you know b1,b2are complex, tell it ComplexExpand(see my modified answer) $\endgroup$ Commented Mar 19, 2021 at 18:05
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    $\begingroup$ (Ψconj = Assuming[Element[{t, ω1, ω}, Reals], ComplexExpand[Conjugate[Ψ], {b1, b2}, TargetFunctions -> Conjugate] // Simplify]) // TraditionalForm $\endgroup$
    – Bob Hanlon
    Commented Mar 19, 2021 at 19:21
  • $\begingroup$ @TubularHell Ulrich may be overthinking regarding how to achieve such formatting. Ulrich, you may simply add //FullSimplify//TraditionalForm to your last example to achieve OP’s desired form. $\endgroup$ Commented Mar 19, 2021 at 19:27

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