Optical control of non-equilibrium superconducting phase transition below Tc in a cuprate

TL;DR

This study demonstrates optical control over a purely electronic non-equilibrium phase transition in a cuprate superconductor, achieved through ultrashort laser pulses that induce a transition from superconducting to normal state without significant heating.

Contribution

It provides the first evidence of optically inducing a non-thermal, purely electronic phase transition in a cuprate superconductor, revealing new control mechanisms for quantum phases.

Findings

Abrupt transition at a critical laser fluence of 70 μJ/cm^2

Transition consistent with an inhomogeneous first-order superconducting-normal phase change

Triggered by a sudden shift of the chemical potential

Abstract

Photoinduced phase transitions from insulating to metallic states, accompanied by structural re-arrangements, have been recently reported in complex transition-metal oxides. However, the optical control of a purely electronic phase transition, where the thermodynamic phase is determined by the distribution of excitations, has remained elusive. Here we report optical control of the electronic phase in an underdoped Bi2212 crystal through impulsive photoinjection of quasiparticles (QP) via ultrashort laser pulses, avoiding significant laser heating. An abrupt transition of the transient optical electronic response is observed at a critical fluence of Ipump=70 uJ/cm^2. We show that the measured dynamics is consistent with an inhomogenous first-order superconducting-to-normal state phase transition, triggered by a sudden shift of the chemical potential.