What Does Entanglement Look Like Inside a Black Hole? | Ivette Fuentes

Closer To Truth
Closer To TruthApr 13, 2026

Why It Matters

Understanding how entanglement degrades near horizons clarifies the information paradox and guides the development of quantum technologies that exploit relativistic effects.

Key Takeaways

  • Entanglement degrades for observers outside a black hole horizon.
  • Acceleration of observers determines degree of observed entanglement loss.
  • Cosmic expansion can generate entanglement, while horizons diminish it.
  • Quantum information tools help probe quantum‑gravity interplay and sensor design.
  • Future work targets quantum‑gravity models and gravity measurement patents.

Summary

In a recent interview, quantum‑information physicist Ivette Fuentes explains how entanglement behaves when one or both parties fall into a black hole, and why the perspective of distant observers matters.

She shows that the shared quantum state is not invariant: observers outside the horizon see a reduced amount of entanglement, with the degradation scaling with their acceleration. In the limit of infinite acceleration the entanglement vanishes, while moderate accelerations produce a graded loss. Her calculations also reveal that expanding spacetime can create entanglement, whereas horizons tend to destroy it.

Fuentes cites her “Alice falls into a black hole” paper and a review on observer‑dependent entanglement as concrete examples, and mentions a patented quantum‑gravity sensor that emerged from these theoretical insights.

These findings bridge quantum optics and general relativity, offering new tools for quantum‑gravity models, informing the design of quantum sensors, and potentially shaping future quantum‑computing architectures.

Original Description

Information has become increasingly important in understanding the physical world around us, from ordinary computers to the underlying principles of fundamental physics, including quantum theory. How can information help discern physics? What can physics contribute to understanding information? And what about quantum information?
Ivette Fuentes is a Professor of Quantum Physics at the University of Southampton and Emmy Fellow at Keble College, University of Oxford. Her work considers fundamental quantum mechanics, quantum optics and their interplay with general relativity.
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