Figure 1

The scheme of entanglement swapping protocol. At first, four entangled transmon qubit pairs \((1,\,2)\), \((3,\,4)\), \((5,\,6)\) and \((7,\,8)\) have been considered such that each pairs of the entangled qubits has been placed on a separate chip. The transmon qubits \((2,\,3)\), \((6,\,7)\) and then \((4,\,5)\) are capacitively coupled to each other respectively via capacitance inductance \(C_i\) \((i=1,\,2,\,3)\). The tunable interaction between each of the two qubits can be realized by varying the frequency of the external magnetic field, through the jth qubit \((j=3,\,5,\,7)\). Finally, the target qubits (1, 8) are entangled.