Journal Club

Seminar Room

Monday 4th of May, 2026

Hour: 12:00

Title: Searching for axions with quantum interferometry

Presented by: Fuensanta Vilches Bravo

Ref: https://arxiv.org/pdf/2604.13181

Abstract:

Quantum phase measurements offer a complementary route to axion searches. We show that axion-photon interactions can imprint both Aharonov-Bohm (AB) and Berry phases in experimentally motivated quantum setups. For a coherently oscillating axion dark matter background, the induced effective current generates a time dependent magnetic flux in an rf-SQUID, leading to a measurable voltage signal through the Josephson phase. For representative benchmarks, this AB phase search reaches the minimum axion-photon coupling g_min ∼ 7.8 × 10^{−14} GeV^{−1} at axion mass m_a ∼ 10−10 eV, with projected sensitivity that can improve on existing limits in that parameter space by roughly one to two orders of magnitude. We also identify a geometric phase observable in a Mach-Zehnder interferometer with an adiabatically rotating magnetic field, providing a proof-ofprinciple phase-based probe of meV-scale axions even when they do not constitute the dark matter, although sensitivity on the coupling remains weaker than current bounds with conservative tabletop benchmarks. Extending the analysis to a three level photon-axion quasiparticle (AQP)-axion system, with the AQP realized in a topological magnetic insulator, we find a potentially measurable THz Berry phase dominated by the AQP sector, furnishing a nontrivial validation of the formalism in a richer coupled system. These setups establish quantum phase observables as a useful new framework for axion searches, with immediate phenomenological promise in superconducting circuits and longer term potential in quantum enhanced interferometry.

Hour: 12:30

Title: Quirks Live in Cool Universes

Presented by: Maria Cristina Fiore

Ref: https://arxiv.org/pdf/2512.20696

Abstract:

We demonstrate that cosmological observations place strong bounds on the reheat temperature TRH of the Standard Model (SM) in minimal models of ‘quirks’ – heavy fermions transforming under the SM gauge group together with a new non-Abelian gauge interaction with a confinement scale far below the mass of the fermions. These models have unique collider signals associated with the confining flux strings, which cannot break due to the large mass of the quirks. Our work shows that in these models T_RH <= O(100) GeV for the entire ‘quirky’ parameter space where the effects of the flux string are important. These bounds are in tension with most models of baryogenesis, showing that the discovery of quirks at colliders can have far-reaching implications for cosmology. The bounds arise because the irreducible relic abundance of glueballs from UV freeze-in, combined with their long lifetimes, leads to constraints from the disruption of BBN, distortions of the CMB, excess γ-rays, an over-abundance of selfinteracting dark matter, and contributions to ∆Neff. The glueball freeze-in abundance has a strong dependence on TRH, making the bounds relatively insensitive to strong interaction uncertainties. The bounds are robust to the SM quantum numbers of the quirks and the presence of Yukawa couplings with the Higgs. In non-minimal extensions
of the model where the glueballs can decay to an additional dark sector, the bounds remain for models where the flux string has a macroscopic length at colliders. We also show that for quirk masses above ~ 10 TeV, the dark glueballs can be the dominant component of dark matter. This work illustrates a striking connection between quirky collider signals and cosmological probes of new physics, strengthening the case for targeted quirk searches at colliders.