Superconductivity is a fascinating phenomenon, which allows a material to sustain an electrical current without any loss. This collective quantum behavior of matter only appears in certain conductors at temperatures far below ambient.
A number of modern studies have investigated this behavior in so-called non-equilibrium states, that is in situations in which the material is pushed away from thermal equilibrium. In these conditions, it appears that at least some of the features of superconductivity can be recreated even at ambient temperatures.
Such non-equilibrium high temperature superconductivity, shown to exist under irradiation with a laser pulse, may be useful for applications different from the ones envisaged for the stationary version of superconductivity, as for example in high-speed devices controlled by laser pulses.
This phenomenon has been termed "light-induced superconductivity," signaling an analogy with its equilibrium counterpart.
An important frontier in the past decade has been to characterize the properties of one such light-induced superconducting state and understand how far this phase reproduces the known properties of a conventional superconductor.
Besides being capable of transporting electrical currents without loss, superconductors are also known to expel magnetic fields from their interior.
This phenomenon, known in equilibrium conditions as the Meissner effect, is a direct consequence of the mutual coherence of the charge carriers and of their tendency to march in lockstep. However, measuring the expulsion of magnetic fields for light-induced superconductivity has been challenging, because the effect only persists for a few picoseconds (one trillionth of a second), making it impossible to measure magnetic field changes with precision.
A team of researchers at the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) in Hamburg, Germany, led by Andrea Cavalleri, has developed a new experiment capable of monitoring the magnetic properties of superconductors at very fast speeds.
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