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Updated: Aug 23, 2025

A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference
Published on: September 5, 2019
Berry Phase from the Entanglement of Future and Past Light Cones: Detecting the Timelike Unruh Effect
James Q Quach1,2, Timothy C Ralph3, William J Munro4,5
1Institute for Photonics and Advanced Sensing and School of Physical Sciences, The University of Adelaide, South Australia 5005, Australia.
Abstract:
The Unruh effect can not only arise out of the entanglement between modes of left and right Rindler wedges, but also between modes of future and past light cones. We explore the geometric phase resulting from this timelike entanglement between the future and past, showing that it can be captured in a simple Λ system. This provides an alternative paradigm to the Unruh-deWitt detector. The Unruh effect has not been experimentally verified because the accelerations needed to excite a response from Unruh-deWitt detectors are prohibitively large. We demonstrate that a stationary but time-dependent Λ-system detects the timelike Unruh effect with current technology.
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