arXiv subjects

Raul Aguero-Santacruz

Publications and source records attributed to Raul Aguero-Santacruz.

4 recordsLinked to original sources

arXiv2026

Backreaction of stimulated Hawking radiation in an optical analogue

Hawking radiation - the emission of quantum particles at the event horizon of a black hole - connects gravity with quantum mechanics and thermodynamics; the Bekenstein-Hawking entropy has been the benchmark for potential quantum theories of gravity. But Hawking radiation has never been observed in astronomy, only in laboratory analogues and the chances of ever observing it in space are astronomically small. The energy of Hawking radiation must come from the gravitational field around the black hole, but how field quanta generate Hawking quanta has been unknown. Here we report on experimental and theoretical evidence for the process that generates Hawking radiation in a fibre-optical analogue of the event horizon. There, as in gravity, it has been believed that Hawking radiation comes from a complicated, cascaded process; here we have found a simple, direct process and measured its backreaction on the field. Our findings suggest an equally direct process for other laboratory analogues and perhaps also for gravitational fields, shedding light on how black holes might radiate.

gr-qc↗

arXiv2023

Negative frequencies and negative norms in analogue Hawking radiation systems

In this work, we study the core concepts of Hawking radiation in the astrophysical and analogue systems. We focus on the definitions of negative frequencies and negative norms: their relationship and their role in the particle creation process of the Hawking effect. We characterize the dispersion relation by the signs of the frequency and the norm. We conclude that the most natural frame for studying the Hawking effect is in the frame in which the horizon is static, where the sign of the norm can be made equal to the sign of the Doppler-shifted frequency in that frame. We use as examples the four most successful experimental analogue systems: water waves, Bose-Einstein condensates, polaritons fluids, and optical fibers.

gr-qc↗

arXiv2023

Negative frequencies in pulse propagation equations and the double analytic signal

In recent years, the topic of negative frequencies has resurfaced in optics motivated by the optical analogue of Hawking radiation. We discuss the physical meaning of negative frequencies and the conditions under which they are relevant. We review how negative frequencies are treated in current pulse propagation models based on the electric field and the analytic signal. We focus on experimentally measured signals predicted by the conservation of negative comoving frequency in the nonlinear polarization terms to advance these concepts. We propose a new formalism called the double analytic signal which clearly separates negative frequencies from positive ones. Additionally, we reduce this new formalism to the analytic signal to prove their equivalence. Throughout the paper, we present numerical solutions of the unidirectional pulse propagation equation to illustrate the electric field, analytic signal, and double analytic signal formalisms and to highlight their differences.

physics.optics↗

arXiv2020

Hawking radiation in optics and beyond

Hawking radiation was originally proposed in astrophysics, but it has been generalized and extended to other physical systems receiving the name of analogue Hawking radiation. In the last two decades, several attempts have been made to measure it in a laboratory, one of the most successful systems is in optics. Light interacting in a dielectric material causes an analogue Hawking effect, in fact, its stimulated version has already been detected and the search for the spontaneous signal is currently ongoing. We briefly review the general derivation of Hawking radiation, then we focus on the optical analogue and present some novel numerical results. Finally, we call for a generalization of the term Hawking radiation.

gr-qc↗