Detecting quantum chaos via pseudo-entropy and negativity

Mar 9, 2024
31 pages
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Abstract: (arXiv)
Quantum informatic quantities such as entanglement entropy are useful in detecting quantum phase transitions. Recently, a new entanglement measure called pseudo-entropy was proposed which is a generalization of the more well-known entanglement entropy. It has many nice properties and is useful in the study of post-selection measurements. In this paper, one of our goals is to explore the properties of pseudo-entropy and study the effectiveness of it as a quantum chaos diagnostic, i.e. as a tool to distinguish between chaotic and integrable systems. Using various variants of the SYK model, we study the signal of quantum chaos captured in the pseudo-entropy and relate it to the spectral form factor (SFF) and local operator entanglement (LOE). We also explore another quantity called the negativity of entanglement which is a useful entanglement measure for a mixed state. We generalized it to accommodate the transition matrix and called it pseudo-negativity in analogy to pseudo-entropy. We found that it also nicely captures the spectral properties of a chaotic system and hence also plays a role as a tool of quantum chaos diagnostic.
Note:
  • 31 pages, 12 figures
  • entropy: entanglement
  • operator: local
  • chaos
  • spectral
  • capture
  • critical phenomena
  • integrability
  • mixed state
  • form factor
  • Sachdev-Ye-Kitaev