All Van der Waals Josephson Junctions
Abstract
Two-level-systems (TLSs) are identified as a major coherence-limiting factor thatexist both within and at the interface of amorphous oxides found in current superconducting quantum circuits. Design improvements that reduce the spurious coupling to TLSs have led to significant improvements of superconducting qubit coherence over the past two decades. However, material and fabrication advancementthat reduce the sources of TLSs has been relatively limited. Van der Waals (vdW)materials and their heterostructures are known for their extraordinary crystallinequality, versatile electronic properties, and flexible assembly that can be achievedwith epitaxially-precise interfaces. In this thesis, we aim to explore and incorporatethe advantages of vdW materials into the circuit quantum electrodynamics (cQED)platform of relevance to advancing quantum technologies. In particular, we fabricate and characterize high-quality, all-vdW Josephson junctions, a key component in superconducting quantum circuits. VdW heterostructures of 2-4 layers ofhBN sandwiched between NbSe2 superconductors demonstrate Josephson effectand the critical current increases exponentially with decreasing hBN layer number. Additionally, we observed a superconducting gap close to the bulk NbSe2 gap, = 1.1 meV in all the vdW junctions, evidencing little degradation of superconductivity. We expect these efforts will lead to high-coherence all-vdW qubit deviceswith small footprints.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 28, 2021
- Accession Number
- AD1222603
Entities
People
- Qing Li
Organizations
- Massachusetts Institute of Technology