Spinlock.m

Analytical approximation to a spin locking process.

Syntax

    rho=spinlock(spin_system,Lx,Ly,rho,direction)

Description

This function obliterates all spin-spin correlations and all magnetization components other than those along the indicated direction. The function destroys all magnetization except in the direction indicated, but does not prevent its subsequent evolution.

Arguments

     Lx         - X magnetization operator on the spins that
                  should be locked

     Ly         - Y magnetization operator on the spins that
                  should be locked

     rho        - state vector or a bookshelf stack thereof

     direction  - direction in which the spins should be lo-
                  cked, 'X' or 'Y'.

Returns

     rho        - state vector or a bookshelf stack thereof

Examples

The following code fragment is used for spin locking in roesy.m:

    % Pulse operators
    Lp=operator(spin_system,'L+',parameters.spins{1});
    Lx=(Lp+Lp')/2; Ly=(Lp-Lp')/2i;

    % Analytical spin lock
    rho_stack_cos=spinlock(spin_system,Lx,Ly,rho_stack,'Y');
    rho_stack_sin=spinlock(spin_system,Lx,Ly,rho_stack,'X');

Notes

This is an approximation to what happens during a real spin locking process. If you need a very accurate simulation, you would need to model the spin locking explicity by adding RF terms to the system Hamiltonian.

See also

coherence.m, correlation.m, homospoil.m

Version 1.10, authors: Ilya Kuprov