How do you approach the concept of quantum phase transitions in your theoretical work?

Sample interview questions: How do you approach the concept of quantum phase transitions in your theoretical work?

Sample answer:

1. Identify the relevant degrees of freedom: Determine the minimal set of variables that adequately describe the system’s behavior near the quantum phase transition. This may involve identifying the order parameter, which is a quantity that distinguishes the different phases of the system.

2. Construct an effective model: Develop a simplified model that captures the essential physics of the quantum phase transition. This model should be mathematically tractable and allow for analytical or numerical analysis. Common approaches include:

   • Landau theory: This phenomenological approach assumes a continuous order parameter and expands the free energy in powers of the order parameter.
   • Ginzburg-Landau theory: This extension of Landau theory includes gradient terms that account for spatial variations of the order parameter.
   • Quantum field theory: This microscopic approach describes the system in terms of fundamental fields and interactions.

3. Analyze the model: Use analytical or numerical techniques to study the behavior of the effective model. This may involve ca… Read full answer

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