n_bit_subtraction

subtraction of two n_bit numbers using qiskit

This is a qiskit algoritham to subtract a decimal number from another number.
libraries needed :-

1. python3.
2. qiskit .
3. qiskit.visualization.
   Two do subtraction of bits with carry the following code is used:-

• qc.cx(i,i+1)
• qc.cx(i+2,i+4)
• qc.ccx(i,i+1,i+2)
• qc.cx(i+2,i+4)
  The number of bit of the biggest number has to be given as input.
  The total number of bits used 2*n+1