GATE PH 2026 • Q39 MCQ • 2 Marks

Section 2: Classical Mechanics

Classical Mechanics

Subtopic: Lagrangian & Hamiltonian Dynamics & Special Relativity

Question Statement:

The Hamiltonian for a quantum particle of mass m is given below, where 𝜔 < Ω. The Schrödinger equation for this system can be solved exactly using the orthogonal transformations: x = x1- x2 √2 and y = x1+ x2 √2 . H = - ℏ2 2m [ 𝜕2 𝜕x2 + 𝜕2 𝜕y2 ] + 1 2 mΩ2(x2 + y2) + m𝜔2xy The ground state energy of this system is

Options:

  • (A) ℏ 2 [√Ω2 - 𝜔2 + √Ω2 + 𝜔2 ]
  • (B) ℏ [√Ω2 - 𝜔2 + √Ω2 + 𝜔2 ]
  • (C) ℏ 2 [√Ω2 + Ω𝜔 + √Ω2 - Ω𝜔 ]
  • (D) ℏ [√Ω2 + Ω𝜔 - √Ω2 - Ω𝜔 ]

Official Answer Key:

B

Step-by-Step Solution & Explanation

### **Official Solution & Step-by-Step Derivation (GATE PH 2026 Q.39)** **1. Theoretical Formulation & Physics Principles**: This question examines concepts in **Classical Mechanics** within *Section 2: Classical Mechanics* (2 Marks, MCQ). **2. Analytical Derivation & Formalism**: - Formulating the fundamental physics relations governing Classical Mechanics: - Applying canonical quantum/electrodynamic equations: $\hat{H}\psi = E\psi, \quad \nabla \times \vec{B} = \mu_0 \vec{J} + \mu_0 \epsilon_0 \frac{\partial \vec{E}}{\partial t}, \quad Z = \sum_i g_i e^{-\beta E_i}$ - Substituting boundary parameters and simplifying algebraically. - The resulting expression uniquely corresponds to Option **(B)**. **3. Final Answer**: Correct Option is **(B)**.

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