Gravitational waves and atoms: From imprints on spontaneous emission to gravitational wave-induced superradiance

ABSTRACT

I will discuss two of our recent works reporting two distinct ways in which a gravitational wave (GW) can affect photon emission from atoms by shaping the electromagnetic vacuum. In a single atom, though the photon emission rate remains unaffected by a GW to leading order in the wave’s amplitude, the effects show up in the directionality and spectrum of emitted photons. The effects benefit from a long integration time made available by ultra-narrow optical transitions in atoms. An idealized analysis of the information about the GW extractable from these effects suggests that the effects could be measured in state-of-the-art cold-atom experiments and points to spontaneous emission as a potential probe of millihertz frequency GWs.

On the other hand, we address the problem of effects of spacetime geometry on quantum systems being typically very small by demonstrating a coherent many-body mechanism that can enhance these effects. We show that, in an ordered array, a GW induces long-range all-to-all dissipative coupling among atoms within half the gravitational wavelength. This coupling is mediated by the electromagnetic vacuum and leads to cooperative photon emission that we term gravitational wave-induced photon superradiance—delayed and intense emission of photons at frequencies shifted from the atomic transition by the GW frequency. The phenomenon arises in a regime distinct from flat-spacetime superradiance, allowing gravitational effects to dominate the collective photon emission from atoms. It persists despite common experimental challenges in atom arrays such as position disorder and partial filling. We thus identify a new class of effects arising from the interplay of general relativity and collective quantum optics that individual atoms do not exhibit.

Our work demonstrates that atomic clouds and engineered collective quantum systems provide a new window into the interplay of general relativity and quantum mechanics.

References: Gravitational Wave-Induced Superradiance in Ordered Atomic Arrays, arXiv:2408.12436; Gravitational Wave Imprints on Spontaneous Emission, Phys. Rev. Lett. 136, 113201 (2026).

BIOGRAPHY

Navdeep Arya is currently a Postdoctoral Researcher at the Stockholm University (Sweden). He obtained his Ph.D. in Theoretical Physics from the Indian Institute of Science Education and Research (IISER), Mohali (India). His current research interests include the use of atomic, optical, and mechanical systems to probe fundamental phenomena.