Visualizing paired electron pockets in the underdoped cuprates using ARPES in the presence of a current

We propose an experiment to test a theory of the underdoped cuprates, which assumes that the pseudogap contains a phase-incoherent paired electron pocket and unpaired hole pockets. The proposed experiment involves angular-resolved photoemission spectroscopy (ARPES) measurements performed in the pseudogap regime and in the presence of a transport current running through the sample. The current leads to two main effects on the spectral function: First, even a weak current tilts the Fermi surface and is predicted to open up a part of the electron pocket if the energy of the incident photons is smaller but close to the pseudogap. Second, stronger currents suppress pairing of the electron pocket, which too can be observable by ARPES. The observation of these predicted phenomena, including their temperature and current dependencies, should clarify the central question about the existence of pairs in the enigmatic pseudogap region.