Fermions in a one-dimensional harmonic potential

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SUMMARY

This discussion focuses on the quantum mechanics of two identical spin-1/2 fermions in a one-dimensional harmonic potential described by the potential function V(x)=(1/2) m w^2 x^2. The key tasks include finding the energies and eigenstates of the ground and first excited states, as well as calculating the square of the separation of the two fermions for the lowest energy state. The discussion emphasizes the differences in behavior between fermions and bosons, particularly regarding occupancy of energy levels.

PREREQUISITES
  • Understanding of quantum mechanics principles, specifically fermions and bosons.
  • Familiarity with harmonic oscillator wavefunctions.
  • Knowledge of spin-1/2 particle behavior.
  • Ability to perform calculations involving expectation values in quantum systems.
NEXT STEPS
  • Study the derivation of harmonic oscillator wavefunctions for spin-1/2 particles.
  • Learn about the Pauli exclusion principle and its implications for fermions.
  • Explore the calculation of expectation values in quantum mechanics.
  • Investigate the differences in statistical mechanics between fermions and bosons.
USEFUL FOR

Quantum physicists, graduate students in physics, and researchers studying many-body quantum systems will benefit from this discussion.

MeiLai
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Two identical spin-1/2 fermions are placed in the one-dimensional harmonic potential

V(x)=(1/2) m w^2 x^2,

where m is the mass of the fermion and w its angular frequency.



(1) Find the energies of the ground and first excited states of this two-fermion system. Express the eigenstates corresponding to these two energy levels in terms of harmonic oscillator wavefunctions and spin states.



(2) Calculate the square of the separation of the two fermions,

<(x1-x2)^2>=<(x1^2+x2^2-2x1x2)>

for the lowest energy state of the two-fermion system.



[(3) Repeat the calculations for the first excited states.]




~~So I'm unsure how to add the spatial components to that or if it's a good start at all. I've only done this for parrallel spin stuff
 

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Quickie hint: what is the difference between a system of bosons and one of fermions regarding particles occuping the same ground state energy level? You've stated you know how to do it for parallel spins... so how will it change slightly for this system?
 

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