# Modeling low- and high-frequency noise in transmon qubits with resource-efficient measurement

## TL;DR

This paper develops a resource-efficient model of noise in transmon qubits, capturing both low- and high-frequency effects, validated through experiments and fidelity measurements, improving understanding of decoherence mechanisms.

## Contribution

The paper introduces a hybrid noise model combining low- and high-frequency effects using the Redfield master equation, validated with IBM quantum devices, and emphasizes the importance of including both noise types for accurate predictions.

## Key findings

- Model accurately predicts fidelity decay under various conditions.
- Including both high- and low-frequency noise improves model accuracy.
- Experimental validation confirms the model's effectiveness.

## Abstract

Transmon qubits experience open system effects that manifest as noise at a broad range of frequencies. We present a model of these effects using the Redfield master equation with a hybrid bath consisting of low and high-frequency components. We use two-level fluctuators to simulate 1/f-like noise behavior, which is a dominant source of decoherence for superconducting qubits. By measuring quantum state fidelity under free evolution with and without dynamical decoupling (DD), we can fit the low- and high-frequency noise parameters in our model. We train and test our model using experiments on quantum devices available through IBM quantum experience. Our model accurately predicts the fidelity decay of random initial states, including the effect of DD pulse sequences. We compare our model with two simpler models and confirm the importance of including both high-frequency and 1/f noise in order to accurately predict transmon behavior.