Speaker: Caterina Braggio (Dipartimento di Fisica e Astronomia – Universita` di Padova)
Title: “Dark matter search goes quantum: improving the sensitivity in axion detection with superconducting circuits”
Abstract:
A factor five discrepancy between the observed density of gravitating and luminous matter in galaxies, including the Milky Way, is the extent of the greatest unknown in Physics: Dark Matter.
In the past 40 years laboratory searches have focused on weakly interacting massive particle (WIMP) dark matter. The observable in this case is the deposit of a tiny, discrete amount of energy when these hypothetical particles collide with the detector active material. The WIMP hypothesis is now somewhat disfavoured by null results, and the interest of the scientific community has broadened to light and ultralight DM. In this scenario particle masses are smaller than ~1 eV, and appear as a background of oscillating fields with De Broglie wavelength greater than ~mm. Searching for this latter class of signals requires detectors at the ultimate level of sensitivity allowed by quantum mechanics. I will show how the ability to control and read out quantum systems is opening new opportunities in advancing the search for DM in the laboratory.
I will focus on cavity-based searches of axion dark matter, where vacuum fluctuations of the cavity field fundamentally limit the sensitivity to an axion-induced signal. With today’s leading technology based on microwave cavities and quantum-limited linear amplifiers, it may take centuries to probe the existence of this leading DM candidate through the most plausible parameter space. Current efforts to readout microwave cavities using quantum sensors will be described, including single microwave photon detectors based on superconducting qubits. This quantum technology represents a breakthrough in the field of dark matter detection, that can in principle introduce a thousandfold enhancement of the search speed compared to low noise receivers based on phase-preserving amplification.