What Does h.c. Signify in Quantum Mechanics Formulas?

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SUMMARY

The discussion clarifies that "h.c." in the interaction Hamiltonian formula represents the Hermitian conjugate. The formula provided describes the interaction of an atom with a photon, incorporating the transition dipole moment \mu and polarization states \epsilon_{1} and \epsilon_{2}. The participants confirm that when writing the second term explicitly, the transition dipole moment \mu and polarization vectors remain unchanged, while the Pauli spin-flip operator \sigma^{-} transforms to \sigma^{+}, and the creation operator a^{+}_{s} changes to the annihilation operator a_{s}. Additionally, the variable g is identified as the gyromagnetic ratio.

PREREQUISITES
  • Understanding of quantum mechanics principles, particularly Hamiltonians.
  • Familiarity with operators in quantum mechanics, including creation and annihilation operators.
  • Knowledge of polarization states in quantum optics.
  • Basic grasp of the Pauli spin matrices and their properties.
NEXT STEPS
  • Study the derivation and applications of interaction Hamiltonians in quantum mechanics.
  • Learn about the properties and implications of Hermitian conjugates in quantum operators.
  • Explore the role of the gyromagnetic ratio in quantum systems and its physical significance.
  • Investigate the use of polarization states in quantum optics and their measurement techniques.
USEFUL FOR

Quantum physicists, students of quantum mechanics, and researchers in quantum optics will benefit from this discussion, particularly those interested in Hamiltonian formulations and operator algebra.

phonon44145
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A textbook gives the following interaction Hamiltonian describing the interaction of an atom (having transition dipole moment \mu) with a photon whose polarization can be \epsilon_{1} or \epsilon_{2}):

H = g \Sigma^{2}_{s=1}\mu\bullet\epsilons\sigma^{-}a^{+}_{s} + h.c.

where \sigma^{-} is Pauli spin-flip operator and a^{+}_{s} is the creation/annihilation operator.

What does "h.c." stand for in this formula?
 
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Hermitean conjugate.
 
Thanks for the quick reply. But I still cannot quite see how to write the second term explicitly. Am I correct in assuming that μ and ϵ1, ϵ2 should not change, σ− will become σ+, and creation operator will change to annihilation operator?
 
Also, what does g stand for - gyromagnetic ratio?
 

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