Quantum mechanics george notes Flashcards

1
Q

what is quantum mechanics written in terms of

A

eigen equations

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2
Q

what does an eigen equation have

A

eigen functions, eigenvalue, and an operator

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3
Q

what is the general form of an eigen equation

A

operator (acts on ) eigen function = eigen value X eigen function

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4
Q

what is the position operator in 1D

A

X

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5
Q

What is the momentum operator

A

p^=-ih(bar)d/dx or p^=-iH(bar)GRAD

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6
Q

kinetic energy

A

T=p^2/2m

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7
Q

kinetic energy operator

A

T^=P^2/2m = -h(bar)/2m d^2/dx^2 = -h(bar/2m (GRAD^2)

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8
Q

what is Hamiltonian operator

A

the total energy operator

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9
Q

what is the eigen equation for the total energy

A

H^ x (wavefunction) = E x (wavefunction )

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10
Q

what is the expectation value

A

the expectation value of a system is the value you expect to get. position, momentum and energy have expectation value other variables do too.

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11
Q

what is degeneracy

A

when two different quantum states give the same value

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12
Q

what does the wavefunction collapsing mean

A

the wave function collapses when a measurement is performed. when you measure a property of the system you collapse the wavefunction from many possible states to one known state.

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13
Q

orthonormal equation

A

intergrate ϕ*_mϕ_n dτau

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14
Q

what are m and n in the orthonormal equations

A

they are labels for the different states

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15
Q

orthonormal

A

If wave functions are orthonormal then m=n and the integral=1, if m does not equal n then the integral will be equal to 0.

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16
Q

eigen value for the simple harmonic motion well

A

2E/hbarω =2n+1

E= (n+1/2)hbar ω

17
Q

property of a dynamic variable

A

they are always real

18
Q

what is a orthonormal eigen function

A

a non degenerate eigen function is orthonormal

19
Q

Hamiltonian in 3D

A

H^=Hx^ +Hy^ +Hz^

20
Q

symmetric degeneracy

A

when tow quantum numbers are swapped in a symmetric potential, the energy is the same

21
Q

accidental degeneracy

A

E proportional the the sum of ni^2 ,

e.g. n1=7 n2=1 is the same as n1=5 and n2=5