code: def fermi_fourier_trans_inverse_conjugate_4(qubits):
      
  
      yield fswap(qubits[1], qubits[2]),
      yield fermi_fourier_trans_2(qubits[0], qubits[1])
      yield fermi_fourier_trans_2(qubits[2], qubits[3])
      yield fswap(qubits[1], qubits[2])
      yield fermi_fourier_trans_2(qubits[0], qubits[1])
      yield cirq.S(qubits[2]) ** 3
      yield fermi_fourier_trans_2(qubits[2], qubits[3])
      yield fswap(qubits[1], qubits[2])
docs: We will need to map the momentum states in the reversed order for
      spin-down states to the position picture. This transformation can be
      simply implemented the complex conjugate of the former one. We only
      need to change the S gate to S* = S ** 3.
  
      Args:
          qubits: list of four qubits