Once the nanometric structures have been designed, how can nano-superconductivity be measured without destroying these structures? Indeed, experiments have proved that what characterizes superconductivity is a resistance equal to zero. However, in order to measure the resistance, a voltage power supply (such as a battery for instance) has to be plugged to measure the electric current. In order to do that, the nano-object has to be electrically connected, with wires that might be neither as small as a nanometre, neither superconducting !
Today’s research must hence understand the disturbance caused by the connection to the samples. Scientists have created “soft” connections that affect the sample less, using tunneling probes, or influential measurements with no contact. In order to do that, a circle-shaped sample is built and the supercurrent (the current that flows with no energy loss) flowing in this circle is measured thanks to the magnetic field created by this current. This technique requires extremely sensitive magnetic field detectors but at least does not require wire welding!
