Renyi_entropy.py

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# -*- coding: utf-8 -*-
"""
Created on Fri Jun 26 14:42:56 2020
Copyright 2020 Peter Rakyta, Ph.D.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

@author: Peter Rakyta, Ph.D.
"""


from squander import N_Qubit_Decomposition_adaptive  




def create_custom_gate_structure(qbit_num, level_num=2):
    """
    Create gate structure
    """

    from squander import Circuit


    # creating an instance of the wrapper class Circuit
    Circuit_ret = Circuit( qbit_num )  


    Layer = Circuit( qbit_num )
    for target_qbit in range(qbit_num):
        Layer.add_U3(target_qbit, True, True, True )

    Circuit_ret.add_Circuit( Layer )
                  


    for idx in range(0,level_num):

        for target_qbit in range(1, qbit_num-1, 2):

                # creating an instance of the wrapper class Circuit
                Layer = Circuit( qbit_num )

                Layer.add_CNOT( target_qbit=target_qbit, control_qbit=target_qbit+1 )
                Layer.add_U3( target_qbit, True, True, True )
                Layer.add_U3( target_qbit+1, True, True, True )

                Circuit_ret.add_Circuit( Layer )


        for target_qbit in range(0, qbit_num-1, 2):

                # creating an instance of the wrapper class Circuit
                Layer = Circuit( qbit_num )
        
                Layer.add_CNOT( target_qbit=target_qbit, control_qbit=target_qbit+1 )
                Layer.add_U3( target_qbit, True, True, True )
                Layer.add_U3( target_qbit+1, True, True, True )

                Circuit_ret.add_Circuit( Layer )



          
    return Circuit_ret



import numpy as np

    
# the number of qubits spanning the unitary
qbit_num  = 22
level_num = 15

gate_structure = create_custom_gate_structure( qbit_num, level_num )


# get the number of parameters
num_of_parameters = gate_structure.get_Parameter_Num()


# create random parameter set
parameters = np.random.uniform( 0.0, 2*np.pi, (num_of_parameters,) )

# calculate the second Rényi entropy

qubit_list = [0,1]
()

entropy = gate_structure.get_Second_Renyi_Entropy( parameters=parameters, qubit_list=qubit_list )
print( 'The second Renyi entropy is:',  entropy) 


page_entropy = len(qubit_list) * np.log(2.0) - 1.0/( pow(2, qbit_num-2*len(qubit_list)+1) )

print( 'The page entropy: ', page_entropy)