  We report an ultra-low resistance superconducting joint using unreacted
multifilament MgB2 wires produced by tailoring the powder compaction pressure
within the joint with heat treatment conditions. The joint demonstrated an
ultra-low resistance of 5.48 x 10^-15 ohms and critical current (Ic) of 91.3 A
at 20 K in self-field. The microstructural and composition studies of the joint
revealed cracks and a high amount of MgO, respectively. These two features
reduced the Ic of the joint to some extent; nevertheless, the joint resistance
was not affected by it. Our tailored joining process will play a pivotal role
in superconducting joint development.
