Confessions of a Diagonalcoholic!

Every Quantum-problem-solver person is a repeat-offender of a simple crime! Diagonalizing!

I am writing about the philosophy of diagonalizing in a bid to elucidate the underlying motive of the QuTiP functions I am writing.

I am writing about a humble problem of calculating the dispersion relationship. Although, algorithmically or computationally it is not intimidating, it exemplifies one of the most effective diagonalization technique at our disposal-- translational symmetry!

In exact diagonalization of an interacting model translational symmetry technique can become the difference between an in and out-of-reach problem. If a 1d lattice can be resolved into a unit cell repeating N times, the translational symmetry can help reduce the length of the matrix to be diagonalized by a factor of N. For interacting models which scale as 2(or 4) to the power N, this little reduction in size can make a problem solvable with a given computational resource.

Using other symmetries can help with further dimensional reduction. I shall elaborate on our work on a Fermi Hubbard model soon.


Comments

Popular posts from this blog

What I cannot code-up, I do not understand

The storm before the calm?

Come for the bandstructure, stay for the topology