Observation of quantum Hawking radiation and its entanglement in an analogue black hole (1510.00621v3)

Abstract: We observe spontaneous Hawking radiation, stimulated by quantum vacuum fluctuations, emanating from an analogue black hole in an atomic Bose-Einstein condensate. Correlations are observed between the Hawking particles outside the black hole and the partner particles inside. These correlations indicate an approximately thermal distribution of Hawking radiation. We find that the high energy pairs are entangled, while the low energy pairs are not, within the reasonable assumption that excitations with different frequencies are not correlated. The entanglement verifies the quantum nature of the Hawking radiation. The results are consistent with a driven oscillation experiment and a numerical simulation.

• The paper reports the experimental observation of quantum Hawking radiation with a thermal distribution and entanglement in an analogue black hole realized in a Bose-Einstein condensate.
• The analogue black hole is created using a 1D Bose-Einstein condensate with varying flow velocities and a laser potential, enabling measurement of entanglement correlations.
• Findings validate Hawking's predictions, provide insights into the black hole information paradox and quantum gravity research, and suggest applications for other analogue space-time experiments.

Observation of Quantum Hawking Radiation and Its Entanglement in an Analogue Black Hole

The paper presented by Jeff Steinhauer showcases a meticulously conducted experimental observation of spontaneous Hawking radiation within an analogue black hole environment, utilizing a Bose-Einstein condensate as the experimental system. This experiment uniquely captures the quantum vacuum fluctuations that stimulate Hawking radiation and importantly demonstrates the entanglement between Hawking particles and their corresponding partner particles within the condensate.

The Bose-Einstein condensate offers a robust platform for simulating the dynamics of black holes due to its quantum mechanical properties, where sound plays the role of light, and the local flow velocity impacts the spacetime metric of the analogue setup. The experiment detects a characteristic thermal distribution of Hawking radiation, aligning with Hawking's theoretical predictions that the event horizon of a black hole should emit such radiation. High-energy particle pairs exhibit entanglement, a quantum feature that underscores the intrinsic nature of the Hawking radiation observed in this analogue model.

Key Findings

1. Thermal Distribution and Entanglement: The observed Hawking radiation presents an approximately thermal distribution, with high-energy pairs being entangled. This conforms with the predictions of black hole thermodynamics and suggests the quantum nature of such radiation.
2. Experimental Setup: The analogue black hole is realized through a 1D Bose-Einstein condensate of rubidium atoms, confined radially, exhibiting subsonic and supersonic flow regions due to a laser-induced potential step. The experiment successfully measures the correlation functions that mark the entanglement between Hawking and partner particles.
3. Validation through Oscillation: A supplemental experiment involving an oscillating horizon corroborates the main findings, indicating that the correlations and the observed Hawking radiation are influenced by a consistent Hawking temperature across both experiments.

Implications and Future Directions

The results from this paper open several pathways for both theoretical and practical advancements:

• Black Hole Information Paradox: The confirmation of entanglement in Hawking radiation provides critical insights into the black hole information paradox, supporting theories that argue for information preservation in quantum processes.
• Quantum Gravity Research: This experiment forms a foundational piece in the broader exploration of quantum gravity, validating elements of Hawking's theory in a controllable setting and offering a new domain to test ideas about quantum fields in curved spacetime.
• Further Analogue Space-Time Constructs: The methodologies can be expanded to explore other analogue gravity scenarios, potentially probing phenomena like analogue wormholes or event horizons in diverse materials and settings, such as photonic or fluid systems.

The research handled by Steinhauer not only substantiates theoretical frameworks but also invigorates experimental approaches towards understanding complex quantum phenomena in black holes. Future exploration in this direction promises to deepen our comprehension of fundamental physical principles, paving the way for more extensive experimental validations of quantum gravitational theories.