Experimental evidence for a surface distribution of two-level systems in superconducting lithographed microwave resonators

By Jiansong Gao, M. Daal, P. Day, B. Mazin, H. Leduc, A. Vayonakis, Shwetank Kumar, B. Sadoulet, Jonas Zmuidzinas. 2008

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We present measurements of the temperature-dependent frequency shift of five niobium superconducting coplanar waveguide microresonators with center strip widths ranging from 3 to 50 µm, taken at temperatures in the range of 100–800 mK, far below the 9.2 K transition temperature of niobium. These data agree well with the two-level system (TLS) theory. Fits to this theory provide information on the number of TLSs that interact with each resonator geometry. The geometrical scaling indicates a surface distribution of TLSs and the data are consistent with a TLS surface layer thickness of the order of a few nanometers, as might be expected for a native oxide layer.

Subfields: Atomic and Molecular Physics, and Optics, Condensed Matter Physics, Electrical and Electronic Engineering

View Paper: https://www.semanticscholar.org/paper/b1c73d4553e0e394da019a414533a8f97bb4d197

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Citations in the corpus

Origins of Diamond Surface Noise Probed by Correlating Single-Spin Measurements with Surface Spectroscopy (2018, background): “More broadly, the strategy of correlating surface spectroscopy with qubit measurements can be applied to a variety of quantum platforms that also exhibit deleterious effects from surfaces and interfaces, such as superconducting qubits [31], trapped ions [32], and shallow donors [33].”
Low-Disorder Microwave Cavity Lattices for Quantum Simulation with Photons (2012, background): “Usual suspects for these parasitic modes are slot line modes, box modes, and poorly designed microwave circuitry [105, 46, 34, 16].”
High Kinetic Inductance Superconducting Nanowire Resonators for Circuit QED in a Magnetic Field (2015, neutral): “The observed increase of Qi with Pin indicates dominant loss by coupling to spurious two-level systems (TLSs) which saturate at high power [16,30,31].”
A wideband, low-noise superconducting amplifier with high dynamic range (2012, background): “[27] The high resistivity also results in a large penetration depth,[7] in the range 2 − 20μm depending on thickness (20-50 nm typically) and critical temperature Tc, so a uniform current density is readily achieved in our micron-scale wires patterned by optical lithography.”
The physics of superconducting microwave resonators (2008, methodology): “Numerical calculations show that this is consistent with a ∼ 2 nm layer of the TLS–loaded material on the metal surface or a ∼ 3 nm layer on the gap surface, suggesting that native oxides or adsorbed layers may be the TLS host material[72].”