Quantum Sensors for Microscopic Tunneling Systems

Abstract

The anomalous low-temperature properties of glasses arise from intrinsic excitable entities, so-called tunneling Two-Level-Systems (TLS), whose microscopic nature has been baffling solid-state physicists for decades. TLS have become particularly important for micro-fabricated quantum devices such as superconducting qubits, where they are a major source of decoherence. Here, we present a method to characterize individual TLS in virtually arbitrary materials deposited as thin-films. The material is used as the dielectric in a capacitor that shunts the Josephson junction of a superconducting qubit. In such a hybrid quantum system the qubit serves as an interface to detect and control individual TLS. We demonstrate spectroscopic measurements of TLS resonances, evaluate their coupling to applied strain and DC-electric fields, and find evidence of strong interaction between coherent TLS in the sample material. Our approach opens avenues for quantum material spectroscopy to investigate the structure of tunneling defects and to develop low-loss dielectrics that are urgently required for the advancement of superconducting quantum computers.

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Cited by in corpus (16)

• TLS Dynamics in a Superconducting Qubit Due to Background Ionizing Radiation
• High-kinetic inductance NbN films for high-quality compact superconducting resonators
• Probing defect densities at the edges and inside Josephson junctions of superconducting qubits
• Identification of different types of high-frequency defects in superconducting qubits
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• Stabilizing and improving qubit coherence by engineering noise spectrum of two-level systems
• Stabilization of Qubit Relaxation Rates by Frequency Modulation
• Strain-spectroscopy of strongly interacting defects in superconducting qubits
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• Systematic Characterization of Transmon Qubit Stability with Thermal Cycling
• Interacting Defects Generate Stochastic Fluctuations in Superconducting Qubits