Batteries belongs to everyday life. A classical
battery, the Volta’s pile, converts chemical energy into a voltage,
which can power electronic circuits. In many quantum technologies,
circuits or devices are based on superconducting materials. In such
materials, currents may flow without the need of an applied
voltage; therefore, there is no need for a classical battery in
such a system. These currents are called supercurrents because they
do not exhibit any energy losses. They are induced not from a
voltage but from a phase difference of the wave function of the
quantum circuit, which is directly related to the wave nature of
matter. A quantum device able to provide a persistent phase
difference can be seen as a quantum phase battery, which induces
supercurrents in a quantum circuit.
