Tesis doctoral. David Díez Ibáñez (DFTUZ/CAPA)

"Exploring dark matter with quantum-enhanced haloscopes and time projection chambers"
Doctorando: David Díez Ibáñez. Área de Física Atómica, Molecular y Nuclear
Directora: Theopisti Dafni

Abstract:
This thesis presents a study of experimental approaches to dark matter detection, exploring two different technologies:
time projection chambers and emerging quantum sensor technologies. Its goal is to help address one of
modern physics’ central challenges: identifying the nature of dark matter, which constitutes roughly 27% of the Universe.

A major part of the work focuses on gaseous detectors, especially the Micromegas-based TREX-DM experiment for low-mass
WIMP searches. The TREX-DM setup—its construction, shielding, readout, and data acquisition—is described, and results
show stable gain, good energy resolution, and effective background reduction. An important upgrade involves adding GEM
foils to Micromegas planes, boosting gain significantly.

Further developments include a new UV-LED internal calibration system capable of producing photoelectrons from metallic
photocathodes, offering a compact and flexible alternative to radioactive sources. Additional studies of pressure-dependent
gain in several gas mixtures refine optimal operating conditions for future low-background TPCs.
The thesis then turns to axion and dark photon searches, discussing their theoretical foundations and detection concepts
such as haloscopes, which exploit axion–photon conversion in resonant microwave cavities. Limitations set by the Standard
Quantum Limit motivate the move toward quantum-enhanced detection methods.

The final experimental contribution is the DarkQuantum prototype, a quantum sensor based on superconducting transmon
qubits coupled to microwave cavities that enables single-photon detection in the microwave range. The device is characterized
through qubit spectroscopy, coherence measurements, and tailored control pulses. Its first dark-photon exclusion limit shows
leading sensitivity around 5.051 GHz, demonstrating the promise of cryogenic quantum detectors.

Overall, the thesis advances both gaseous detector technology for WIMP searches and quantum sensing techniques for axion
and dark photon detection, illustrating how classical and quantum approaches together can open new avenues in the search for dark matter.

Lugar: Sala de Grados de la Facultad de Ciencias
Día y hora: martes 2 de diciembre, 11:00 horas