PHYSICS DISSERTATION DEFENSE: Stephen Kuenstner

Ph.D. Candidate:  Stephen Kuenstner

Research Advisor:  Kent Irwin

Date: August 17th, 2022
Time: 10 AM

Zoom Link:  https://stanford.zoom.us/j/99204166821

Zoom Password: email nickswan [at] stanford.edu (nickswan[at]stanford[dot]edu) for password.

 

Title: Superconducting Quantum Sensors for Wavelike Dark Matter Searches

Abstract: Discovering dark matter is one of the great challenges in contemporary physics. Successive generations of experiments - each more impressive and sophisticated than the last - have all failed to uncover dark matter's most basic properties. Characterizing dark matter would provide

the first-ever opportunity to study a particle outside the Standard Model, and probing the structure of the Milky Way's dark matter halo would open up an entirely new avenue to study astrophysics and cosmology. However, searching for dark matter typically requires expensive and large-scale experiments. This thesis describes a small part of the ongoing effort to make dark matter searches more tractable by adopting the techniques of quantum information science to engineer non-classical states in the detector. Leveraging these non-classical states in a dark matter detector allows it to greatly exceed the sensitivity of an equivalent, purely classical detector.  In the first part of the thesis I discuss the design, fabrication, and characterization the DM Radio Pathfinder, a modestly-scaled dark matter detector. I use the Pathfinder to set the best laboratory limits on a particular dark matter candidate particle, the hidden photon. Although the detector uses many techniques relevant to quantum information science, including cryogenics and sensitive superconducting circuits, it is a classical experiment which does not achieve any quantum speedup. In the second part of the thesis, I propose the Radio Frequency Upconverter (RQU), a superconducting circuit that could achieve a quantum speedup in a dark matter experiment similar to the Pathfinder. I design and fabricate prototype RQUs and characterize their properties in several experiments. Finally, I propose a realistic path towards using RQUs to achieve a quantum speedup in a real dark matter detector.