Shape optimization of superconducting transmon qubit for low surface dielectric loss

• URL: http://arxiv.org/abs/2211.14159v1
• Date: Fri, 25 Nov 2022 15:03:43 GMT
• Title: Shape optimization of superconducting transmon qubit for low surface dielectric loss
• Authors: Sungjun Eun, Seong Hyeon Park, Kyungsik Seo, Kibum Choi and Seungyong Hahn
• Abstract summary: We present the shape optimization approach for reducing Surface dielectric loss in transmon qubit. The capacitor pad and junction wire of the transmon qubit are shaped as spline curves and optimized through the combination of the finite-element method and global optimization algorithm. As a result, the TLS-limited quality factor and corresponding $T_1$ were increased by approximately 21.6%.
• Score: 1.1228750845630484
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: Surface dielectric loss of superconducting transmon qubit is believed as one of the dominant sources of decoherence. Reducing surface dielectric loss of superconducting qubit is known to be a great challenge for achieving high quality factor and a long relaxation time ($T_{1}$). Changing the geometry of capacitor pads and junction wire of transmon qubit makes it possible to engineer the surface dielectric loss. In this paper, we present the shape optimization approach for reducing Surface dielectric loss in transmon qubit. The capacitor pad and junction wire of the transmon qubit are shaped as spline curves and optimized through the combination of the finite-element method and global optimization algorithm. Then, we compared the surface participation ratio, which represents the portion of electric energy stored in each dielectric layer and proportional to two-level system (TLS) loss, of optimized structure and existing geometries to show the effectiveness of our approach. The result suggests that the participation ratio of capacitor pad, and junction wire can be reduced by 16% and 26% compared to previous designs through shape optimization, while overall footprint and anharmonicity maintain acceptable value. As a result, the TLS-limited quality factor and corresponding $T_{1}$ were increased by approximately 21.6%.

Related papers

• Wiring surface loss of a superconducting transmon qubit [0.0]
  We show that more than 50% of surface loss in transmon qubits can originated from Josephson junctions wiring. We fabricate six tunable floating transmon qubits and experimentally demonstrate up to 20% improvement in qubit quality factor by wiring design optimization.
  arXiv  Detail & Related papers  (2023-11-28T13:59:41Z)
• Enhancing the Coherence of Superconducting Quantum Bits with Electric Fields [62.997667081978825]
  We show that qubit coherence can be improved by tuning defects away from the qubit resonance using an applied DC-electric field. We also discuss how local gate electrodes can be implemented in superconducting quantum processors to enable simultaneous in-situ coherence optimization of individual qubits.
  arXiv  Detail & Related papers  (2022-08-02T16:18:30Z)
• Precision measurement of the microwave dielectric loss of sapphire in the quantum regime with parts-per-billion sensitivity [50.591267188664666]
  Dielectric loss is known to limit state-of-the-art superconducting qubit lifetimes. Recent experiments imply upper bounds on bulk dielectric loss tangents on the order of $100$ parts-per-billion. We have devised a measurement method capable of separating and resolving bulk dielectric loss with a sensitivity at the level of $5$ parts per billion.
  arXiv  Detail & Related papers  (2022-06-29T00:14:11Z)
• Compact vacuum gap transmon qubits: Selective and sensitive probes for superconductor surface losses [0.0]
  State-of-the-art transmon qubits rely on large capacitors which systematically improves their coherence. We present transmon qubits with sizes as low as 36$ times $39$ mu$m$2$ with $gtrsim$100 nm wide vacuum gap capacitors.
  arXiv  Detail & Related papers  (2022-06-28T16:02:08Z)
• Measurement of the Low-temperature Loss Tangent of High-resistivity Silicon with a High Q-factor Superconducting Resonator [58.720142291102135]
  We present the direct loss tangent measurement of a high-resist intrinsicivity (100) silicon wafer in the temperature range from 70 mK to 1 K. The measurement was performed using a technique that takes advantage of a high quality factor superconducting niobium resonator.
  arXiv  Detail & Related papers  (2021-08-19T20:13:07Z)
• Optimal design of a superconducting transmon qubit with tapered wiring [0.0]
  formulas can thus be used to precisely predict loss and optimize the qubit layout. A significant fraction of surface loss comes from the small wire that connects the Josephson junction to the qubit capacitor.
  arXiv  Detail & Related papers  (2021-04-04T06:13:14Z)
• In-situ bandaged Josephson junctions for superconducting quantum processors [101.18253437732933]
  Shadow evaporation is commonly used to micro-fabricate the key element of superconducting qubits - the Josephson junction. Here, we present an improved shadow evaporation technique allowing one to fabricate sub-micrometer-sized Josephson junctions together with bandage layers in a single lithography step.
  arXiv  Detail & Related papers  (2021-01-05T11:08:09Z)
• Quantum Sensors for Microscopic Tunneling Systems [58.720142291102135]
  tunneling Two-Level-Systems (TLS) are important for micro-fabricated quantum devices such as superconducting qubits. We present a method to characterize individual TLS in virtually arbitrary materials deposited as thin-films. Our approach opens avenues for quantum material spectroscopy to investigate the structure of tunneling defects.
  arXiv  Detail & Related papers  (2020-11-29T09:57:50Z)
• Comparison of Dielectric Loss in Titanium Nitride and Aluminum Superconducting Resonators [45.82374977939355]
  Lossy dielectrics are a significant source of decoherence in superconducting quantum circuits. We fabricate isotropically trenched resonators to accentuate a specific dielectric region's contribution to resonator quality factor. We evaluate the quality factor of each TiN resonator geometry with and without a post-process hydrofluoric (HF) etch, and find that it reduced losses from the substrate-air interface.
  arXiv  Detail & Related papers  (2020-07-14T20:20:22Z)
• Effects of device geometry and material properties on dielectric losses in superconducting coplanar-waveguide resonators [0.0]
  Superconducting coplanar-waveguide (CPW) resonators are one of the key devices in circuit quantum electrodynamics (cQED) We present a method for combining loss simulations with measurements of two-level-system-limited quality factors and resonance frequencies of CPW resonators.
  arXiv  Detail & Related papers  (2020-02-28T15:26:41Z)
• Analytical modeling of participation reduction in superconducting coplanar resonator and qubit designs through substrate trenching [0.0]
  Strategy aimed at decreasing dielectric loss in coplanar waveguides and qubits. Conformal mapping techniques produce transformed CPW and qubit geometries without substrate trenching.
  arXiv  Detail & Related papers  (2020-01-30T16:57:44Z)

This list is automatically generated from the titles and abstracts of the papers in this site.

This site does not guarantee the quality of this site (including all information) and is not responsible for any consequences.