GradientDescentDisentangler

• full name: tenpy.algorithms.disentangler.GradientDescentDisentangler

• parent module: tenpy.algorithms.disentangler

• type: class

Inheritance Diagram

Methods

GradientDescentDisentangler.__init__(parent)
GradientDescentDisentangler.iter(theta)	Given theta, find a unitary U towards minimizing the n-th Renyi entropy.

class tenpy.algorithms.disentangler.GradientDescentDisentangler(parent)

Bases: Disentangler

Gradient-descent optimization, similar to RenyiDisentangler.

Options

iter(theta)

Given theta, find a unitary U towards minimizing the n-th Renyi entropy.

This function calculates the gradient \(dS = \partial S(U theta, n) /\partial U\). and then U(t) = exp(-t*dS), where we choose the t from stepsizes which minimizes the entropy of U(t) theta.

When R[i] is the derivative \(\partial S(Y, n)/ \partial Y_i\) of the (n-th Renyi) entropy, dS is given by:

|     .----X--R--Z----.
|     |    |     |    |
|     |    q0    q1   |
|     |               |
|     |    q0*   q1*  |
|     |    |     |    |
|     .----X*-Y--Z*---.

Parameters:

theta (Array) – Two-site wave function to be disentangled

Returns:

• S (float) – n-th Renyi entropy of new_theta

• theta (Array) – The disentangled wave function new_U theta.

• new_U (Array) – Unitary with legs 'q0', 'q1', 'q0*', 'q1*', which was used to disentangle theta.