(a) For a function ƒ(x) that can be expanded in a Taylor series, show that f(x + xo) = ei Pxo/n f(x) (where xo is any constant distance). For this reason, §/ħ is called the genera- tor of translations in space. Note: The exponential of an operator is defined by the power series expansion: e =1+ Ô + (1/2)Q² + (1/3!)ĝ³ +... .....

Advanced Engineering Mathematics
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Chapter2: Second-order Linear Odes
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*Problem 3.39
(a) For a function ƒ(x) that can be expanded in a Taylor series, show that
f(x + xo) = e' Pxo/h ƒ (x)
%3D
(where xo is any constant distance). For this reason, §/ħ is called the genera-
tor of translations in space. Note: The exponential of an operator is defined
by the power series expansion: eº =1+ Ô + (1/2)Q² +(1/3!)ĝ³ + ....
(b) If ¥(x, 1) satisfies the (time-dependent) Schrödinger equation, show that
¥(x,t + to) = e
(where to is any constant tìme); –Ĥ /ħ is called the generator of translations
in time.
:) Show that the expectation value of a dynamical variable Q(x, p, t), at time
t + to, can be written34
(Q)+» = (¥(x, t)le'Hta/h Ô (f. §, 1 + to)e¯iim/^|¥(x,1)).
Use this to recover Equation 3.71. Hint: Let to = dt, and expand to first
order in dt.
%3D
Transcribed Image Text:*Problem 3.39 (a) For a function ƒ(x) that can be expanded in a Taylor series, show that f(x + xo) = e' Pxo/h ƒ (x) %3D (where xo is any constant distance). For this reason, §/ħ is called the genera- tor of translations in space. Note: The exponential of an operator is defined by the power series expansion: eº =1+ Ô + (1/2)Q² +(1/3!)ĝ³ + .... (b) If ¥(x, 1) satisfies the (time-dependent) Schrödinger equation, show that ¥(x,t + to) = e (where to is any constant tìme); –Ĥ /ħ is called the generator of translations in time. :) Show that the expectation value of a dynamical variable Q(x, p, t), at time t + to, can be written34 (Q)+» = (¥(x, t)le'Hta/h Ô (f. §, 1 + to)e¯iim/^|¥(x,1)). Use this to recover Equation 3.71. Hint: Let to = dt, and expand to first order in dt. %3D
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