Merged-element transmon
R. Zhao, S. Park, T. Zhao, M. Bal, C.R.H. McRae, J. Long, and D.P., Pappas

TL;DR
This paper introduces the merged-element transmon, a compact superconducting qubit design that replaces large capacitors with Josephson junctions, significantly reducing device size while maintaining coherence and functionality.
Contribution
It presents the design, fabrication, and experimental validation of the mergemon, demonstrating a 100-fold size reduction and analyzing loss mechanisms for improved qubit coherence.
Findings
Achieved approximately 100 times reduction in qubit size.
Demonstrated qubit-state dependent frequency shifts and multi-photon transitions.
Identified dielectric loss in the tunnel barrier as the main relaxation source.
Abstract
Transmon qubits are ubiquitous in the pursuit of quantum computing using superconducting circuits. However, they have some drawbacks that still need to be addressed. Most importantly, the scalability of transmons is limited by the large device footprint needed to reduce the participation of the lossy capacitive parts of the circuit. In this work, we investigate and evaluate losses in an alternative device geometry, namely, the merged-element transmon (mergemon). To this end, we replace the large external shunt capacitor of a traditional transmon with the intrinsic capacitance of a Josephson junction (JJ) and achieve an approximately 100 times reduction in qubit dimensions. We report the implementation of the mergemon using a sputtered Nb--amorphous-Si--Nb trilayer film. In an experiment below 10 mK, the frequency of the readout resonator, capacitively coupled to the mergemon, exhibits a…
Peer Reviews
No public reviews on file for this paper yet. If you reviewed it on a platform where reviews are public (OpenReview, ICLR, NeurIPS, ICML), you can paste yours below so the community can read it here.
Videos
No videos yet. Explain this paper in a talk, walkthrough, or lecture? Add one.
Taxonomy
TopicsPhotonic and Optical Devices · Quantum and electron transport phenomena · Mechanical and Optical Resonators
