Undergrad Annihilation vs. Creation Operators: What's the Difference?

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SUMMARY

The discussion centers on the fundamental differences between annihilation and creation operators in quantum mechanics, specifically regarding their eigenstates. Coherent states are defined as eigenstates of the annihilation operator, while there are no eigenstates associated with the creation operator. This asymmetry arises from the ordered basis of quantum states, which includes the ground state but lacks a terminal state. The distinction is crucial for understanding quantum state behavior and manipulation.

PREREQUISITES
  • Understanding of quantum mechanics principles
  • Familiarity with operators in quantum theory
  • Knowledge of coherent states and their properties
  • Basic grasp of eigenstates and eigenvalues
NEXT STEPS
  • Research the mathematical formulation of annihilation and creation operators
  • Explore the concept of coherent states in quantum optics
  • Study the implications of eigenstates in quantum mechanics
  • Investigate the role of ordered bases in quantum state representation
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Quantum physicists, students of quantum mechanics, and researchers interested in the mathematical foundations of quantum state manipulation.

gerald V
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Cohererent states are defined as eigenstates of the annihilation operator. Never the creation operator is referred to.

Is this just a convention or is more behind? What is the essential difference between eigenstates of the annihilation- versus the creation operator?

Thank you very much in advance!
 
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There are no eigenstates of the creation operator. The asymmetry between creation and annihilation operators stems from the fact that the ordered basis ##\{|0\rangle, |1\rangle, |2\rangle,\ldots\}## has the first element but not last element.
 
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gerald V said:
What is the essential difference between eigenstates of the annihilation- versus the creation operator?

Existence!
 
Got it. Thank you very much.
 
Time reversal invariant Hamiltonians must satisfy ##[H,\Theta]=0## where ##\Theta## is time reversal operator. However, in some texts (for example see Many-body Quantum Theory in Condensed Matter Physics an introduction, HENRIK BRUUS and KARSTEN FLENSBERG, Corrected version: 14 January 2016, section 7.1.4) the time reversal invariant condition is introduced as ##H=H^*##. How these two conditions are identical?

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