Low frequency Rabi spectroscopy of dissipative two level systems. The dressed state approach

TL;DR

This paper presents a theoretical analysis of a dissipative two-level quantum system under dual-frequency excitation, revealing a resonance-based low-frequency Rabi spectroscopy method applicable to various quantum systems.

Contribution

It introduces a dressed state approach to analyze the response of a dissipative TLS to combined high and low frequency excitations, enabling low-frequency Rabi spectroscopy.

Findings

Resonance at the Rabi frequency with damping-dependent width

Undamped low frequency oscillations in the response

Applicability to systems like NMR, quantum dots, and superconducting qubits

Abstract

We have analyzed a dissipative two level quantum system (TLS) which is continuously and simultaneously irradiated by a high and low frequency excitation. The interaction of the TLS with a high frequency excitation is considered in the frame of the dressed state approach. A linear response of the coupled TLS and corresponding photon field system to a signal whose frequency is of the order of the Rabi frequency is found. The response exhibits undamped low frequency oscillations, whose amplitude has a clear resonance at the Rabi frequency with the width being dependent on the damping rates of the TLS. The method can be useful for low-frequency Rabi spectroscopy in various physical systems described by a two-level Hamiltonian, such as nuclei spins in NMR, double well quantum dots, superconducting flux and charge qubits, etc. The application of the method to a superconducting flux qubit and to the detection of NMR is considered in detail.