Vacuum fluctuations can enhance superconductivity in a bulk material. This is the new finding from researchers in China and the US who have put forward the concept of “vacuumtronics”. This is a new way to tune superconductivity without chemically altering a material, applying pressure to it or driving it with intense light.
In quantum electrodynamics, a vacuum is not empty but is host to fluctuating electromagnetic fields in which pairs of virtual particles are continuously being created and annihilated. Such vacuum fluctuations are thought to be responsible for phenomena like the Lamb shift, spontaneous emission and the Casimir effect.
In recent years researchers have been looking into the possibility of exploiting these fluctuations to change the properties of bulk matter. This is challenging because the fluctuations are extremely weak and produce little measurable change in macroscopic quantum states. They can, however, be amplified by a factor of 100 or even more using structures like resonant cavities. Indeed, such enhanced vacuum fields have already been exploited to modify material properties like chemical reactivity, topological states and conductivity.
In theory, vacuum fluctuations could be used to modulate superconductivity too, but until now this had never been demonstrated in an experiment.
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