OPENQASM 2.0;
include "qelib1.inc";
qreg q[4];
creg c[4];
// Bell pair 1
h q[0]; cx q[0],q[1];
// Bell pair 2
h q[2]; cx q[2],q[3];
// Bell measurement
cx q[1],q[2]; h q[1];
measure q -> c;