# Particle-hole Asymmetry in the Cuprate Pseudogap Measured with Time-Resolved Spectroscopy

## TL;DR

This study uses time-resolved spectroscopy to investigate particle-hole symmetry in cuprate pseudogap states, revealing an asymmetry that informs understanding of high-temperature superconductivity.

## Contribution

Introduces a novel laser-based technique to measure particle-hole symmetry in cuprates on picosecond timescales, providing new insights into the pseudogap state.

## Key findings

- Pseudogap state exhibits particle-hole asymmetry.
- Asymmetry in density of states is inverted in pseudogap.
- Results can test theoretical models of cuprate electronic structure.

## Abstract

One of the most puzzling features of high-temperature cuprate superconductors is the pseudogap state, which appears above the temperature at which superconductivity is destroyed. There remain fundamental questions regarding its nature and its relation to superconductivity. But to address these questions, we must first determine whether the pseudogap and superconducting states share a common property: particle-hole symmetry. We introduce a new technique to test particle-hole symmetry by using laser pulses to manipulate and measure the chemical potential on picosecond time scales. The results strongly suggest that the asymmetry in the density of states is inverted in the pseudogap state, implying a particle-hole asymmetric gap. Independent of interpretation, these results can test theoretical predictions of the density of states in cuprates.