Quantum Many

# Quantum Many-Body Theory Calculation Application A comprehensive iOS application for physicists, materials scientists, and researchers working with quantum many-body theory calculations. ## Features ### 1. Keldysh Closed Time Path (CTP) Analysis - Calculate evolution operators for non-equilibrium quantum systems - Compute two-point correlation functions - Analyze time-ordered, retarded, and advanced correlation functions - Support for custom Hamiltonian and operator inputs ### 2. Non-Equilibrium Green's Functions - Calculate lesser, greater, retarded, and advanced Green's functions - Compute Keldysh Green's functions - Fourier transform between time and frequency domains - Visualize Green's functions in both time and frequency representations ### 3. Quantum Master Equation Solver - Solve Lindblad master equation for open quantum systems - Numerical integration using Runge-Kutta 4th order method - Calculate density matrix evolution - Compute purity and von Neumann entropy - Support for multiple Lindblad operators ### 4. Fluctuation-Dissipation Theorem Verification - Verify quantum fluctuation-dissipation relations - Calculate response functions (susceptibility) - Compute correlation function spectra - Compare response and correlation functions according to FDT ### 5. Open Quantum System Analysis - Study system-environment coupling effects - Calculate decoherence time (T2) - Calculate relaxation time (T1) - Analyze quantum fidelity decay - Compute entanglement evolution using concurrence