Signatures of Enhanced Superconducting Phase Coherence in Optimally Doped Bi2Sr2Y0.08C

Quench–drive spectroscopy of cuprates

“…We now want to describe a state with a superconducting instability and characterized by the presence of pre-formed incoherent pairs, which can be identified as the origin of the pseudogap phase: in this regard, as in Ref. 1 , we use a new artificial equilibrium superconducting state obtained by adding a random momentum-dependent phase φ k to the original Cooper pairs' state. Therefore, the strength of the pairing potential remains unchanged, as well as the number of total Cooper pairs, while the superconducting order parameter decreases due to the reduced coherence.…”

“…In the last years, experiments on high-temperature superconductors have revealed the presence of signatures of superconducting fluctuations above the critical temperature T c . This behaviour has been attributed to incoherent or pre-formed Cooper pairs, leading to third-harmonic generation (THG) and enhancement of the reflectivity change in a pump-probe experimental configuration [1][2][3] . Cuprates are the prototypical example of high-temperature superconductors, exhibiting a complex phase diagram as a function of doping and temperature, with a superconducting dome enriched by charge-density wave and pseudogap phases 4 .…”

“…In the present work, we numerically solve the Heisenberg's equation of motion derived within the pseudospin formalism 29,30 in order to describe the superconducting state, and we support our interpretations and results with the derivation of the nonlin-ear susceptibility by means of a diagrammatic approach 31 . Moreover, in order to treat the pseudogap phase, characterized by incoherent pairs, we extend the pseudospin model artificially adding a phase to the Cooper pairs 1 , and solving the corresponding equations to obtain the time-evolution of the order parameter and the generated nonlinear current (see Fig. 2(b),(c)).…”

Time-resolved ARPES on cuprates: Tracking the low-energy electrodynamics in the time domain

“…QP scattering relaxation pling to any specific collective mode (whose energy scales are commonly sub-100 meV) [2,3,61]. Following the path already set by all-optical studies, where tailored mid-infrared/THz excitations have been used to resonantly excite specific collective modes and drive new phases of matter with no equilibrium counterparts [61][62][63][64][65], next-generation TR-ARPES systems will offer longwavelength pump capabilities, enabling new insights into the light-induced manipulation of the electronic properties of quantum materials with the addition of direct momentum resolution. The potential of these types of experiments has recently been demonstrated in several pioneering works [9,10,66].…”

Nature of superconducting fluctuation in photo-excited systems

“…Such a possibility has been intensively studied by pumpprobe experiments using a laser pulse, and the intriguing photo-excitated states have been created and measured [1][2][3][4][5][6][7][8]. For superconducting materials in strongly correlated systems, recent experiments have shown gigantic enhancement of superconductivity in a photo-induced state [4,[9][10][11][12][13][14][15], which has considerable attention in the physics community. While the change in the electronphonon coupling through the phonon drive has been studied as the origin of the photo-induced superconducting state [16][17][18][19][20][21][22][23][24][25][26], photons also pump the electrons directly.…”