Higginbotham Lab

The Higginbotham group experimentally explores the boundary between condensed-matter physics and quantum information processing.

We are using circuit elements developed for quantum computing both to probe otherwise hidden behavior in materials, and to realize synthetic, effective models of materials physics. We are interested in how these ideas could result in new functionality for quantum information processing and sensing.

Current research topics include:

detecting exotic mechanical responses in quantum materials
non-equilibrium behavior in granular superconductors
engineered and driven phases of Josephson-junction arrays

Recent Research Highlights

Quantum phase transitions in Josephson arrays

Combining microwave spectroscopy and transport measurements of a Josephson Junction array, we uncover evidence that superconductivity is surprisingly robust.

This work explains why quantum criticality is sometimes curiously absent in arrays of Josephson junction, and suggests that, surprisingly, non-zero temperature is useful for improving the performance of some superconducting resonators.

“Superconductivity from a melted insulator”, Mukhopadhyay et al.
Nature Physics (2023)
News & Views: Superconducting arrays offer resistance

Probing quantum materials with microwave resonators

By integrating a microwave resonator with an Al-InAs hybrid material we are able to extract “hidden” properties of the buried interface.

We present the first evidence of induced p-wave pairing and the emergence of Bogoliubov-Fermi surfaces. Our technique probes properties of the semiconductor buried under the aluminum, which are inaccessible to conventional probes.

This approach paves the way for studying and characterization of other hybrid devices that are of great importance to the quantum information processing community.

“Detecting Induced p±ip Pairing at the Al-InAs Interface with a Quantum Microwave Circuit”, D.Phan et al.
Phys. Rev. Lett. (2022)
arXiv:2107.03695

Building new circuit elements from quantum materials

We added a single Josephson junction to a Al-InAs hybrid device to realize a semiconductor-based parametric amplifier operating near quantum limits.

“Gate-Tunable Superconductor-Semiconductor Parametric Amplifier”
D. Phan et al.
Phys. Rev. Applied 19, 064032 (2023). arXiv:2206.05746

Strong coupling from mechanical motion to a transmission line

Coupling between electromagnetic waves and mechanical motion is famously weak. We suspended a silicon nitride membrane covered with metal over a counter electrode to create an electromechanical spring which couples more strongly to transmission lines than to its own internal loss at room temperature.

The strong coupling of the device allows it to detect tiny deflections in the membrane position, which creates an opportunity for us to study exotic behaviors of materials under curvature next.

“Room temperature, cavity-free capacitive strong coupling to mechanical motion”, D. Puglia et al. Nano Letters 2025 25 (7), 2749-2755. arXiv: 2407.15314