# Dynamical Decoupling of Quantum Two-Level Systems by Coherent Multiple Landau-Zener Transitions

## TL;DR

This paper demonstrates that high-speed periodic electric biasing induces multiple Landau-Zener transitions in quantum two-level systems, significantly reducing dielectric loss in superconducting resonators and potentially improving qubit coherence.

## Contribution

It introduces a method of dynamical decoupling of TLSs via coherent multiple Landau-Zener transitions, reducing dielectric loss in superconducting quantum devices.

## Key findings

- High sweep rates lead to reduced dielectric loss.
- The effect occurs in both classical and quantum regimes.
- Potential for dynamic decoupling of TLSs from qubits.

## Abstract

Increasing and stabilizing the coherence of superconducting quantum circuits and resonators is of utmost importance for various technologies ranging from quantum information processors to highly sensitive detectors of low-temperature radiation in astrophysics. A major source of noise in such devices is a bath of quantum two-level systems (TLSs) with broad distribution of energies, existing in disordered dielectrics and on surfaces. Here we study the dielectric loss of superconducting resonators in the presence of a periodic electric bias field, which sweeps near-resonant TLSs in and out of resonance with the resonator, resulting in a periodic pattern of Landau-Zener transitions. We show that at high sweep rates compared to the TLS relaxation rate, the coherent evolution of the TLS over multiple transitions yields a significant reduction in the dielectric loss relative to the intrinsic value. This behavior is observed both in the classical high-power regime and in the quantum single-photon regime, possibly suggesting a viable technique to dynamically decouple TLSs from a qubit.