Research

Our group develops superconducting quantum circuits based on longitudinal qubit coupling, a hardware approach that can simplify control, improve readout, and enable new architectures for quantum information processing. In contrast to conventional transverse coupling, longitudinal interactions can reduce unwanted hybridization between qubits and resonators while still allowing fast measurement and controllable multi-qubit operations. We aim to design, fabricate, and study circuit QED systems that realize strong and tunable longitudinal coupling, and to use them to demonstrate high-fidelity readout and elementary quantum gate operations. Our goal is to establish longitudinal coupling as a practical resource for building larger and more robust superconducting quantum processors.

[1] - Strong intrinsic longitudinal coupling in circuit quantum electrodynamics, C.A. Potts, R.C. Dekker, S. Deve, E.W. Strijbis, G.A. Steele. Physical Review Letters 134, 153603 (2025)
 

We develop hybrid quantum devices that couple superconducting qubits to mechanical resonators, creating a platform for controlling motion at the quantum level. By engineering strong, tunable interactions between qubits and mechanical modes, we aim to transfer quantum states, generate nonclassical mechanical motion, and explore new approaches to sensing and transduction. Our goal is to demonstrate qubit electromechanical systems that expand the reach of superconducting quantum circuits beyond purely electrical platforms.

[1] - Probing the quantum motion of a macroscopic mechanical oscillator with a radio-frequency superconducting qubit, K. Gerashchenko, et al., arXiv:2505.21481

[2] - Kerr enhanced backaction cooling in magnetomechanics, D. Zoepfl, M.L. Juan, N. Diaz-Naufal, C.M.F. Schneider, L.F. Deeg, A. Sharafiev, A. Metelmann, G. Kirchmair, Phys. Rev. Lett. 130, 033601 (2023)

[3] -  Schrödinger cat states of a 16-microgram mechanical oscillator, M. Bild, M. Fadel, Y. Yang, U. Von Lüpke, P. Martin, A. Bruno, Y. Chu, Science 380 (6642), 274-278 (2023)

We develop superconducting quantum circuits for bosonic quantum computing using longitudinally coupled cat qubits. By combining the error-protection of cat states with the advantages of longitudinal coupling, we aim to create architectures with reduced unwanted interactions, improved control, and greater scalability. Our goal is to demonstrate robust bosonic qubits as a path toward fault-tolerant quantum computing.

[1] - Nonlinear Sideband Cooling to a Cat State of Motion, B.D. Hauer, J. Combes, J.D. Teufel, Physical Review Letters 130, 213604 (2023)

[2] - Stabilization and operation of a Kerr-cat qubit, A. Grimm, et al., Nature 584, 205–209 (2020)