Quantum simulations and experiments on Rabi oscillations of spin qubits: intrinsic {\sl vs} extrinsic damping

TL;DR

This paper investigates how Rabi oscillation decay in spin qubits depends on microwave power, showing that dipolar interactions and inhomogeneities can explain driven decoherence through numerical simulations of the Schrödinger equation.

Contribution

It demonstrates that dipolar-coupled spins with inhomogeneities can account for driven decoherence, using direct numerical solutions of the many-body Schrödinger equation.

Findings

Dipolar interactions cause Rabi decay dependent on Rabi frequency.

Inhomogeneities contribute to driven decoherence.

Numerical simulations align with experimental observations.

Abstract

Electron Paramagnetic Resonance experiments show that the decay of Rabi oscillations of ensembles of spin qubits depends noticeably on the microwave power and more precisely on the Rabi frequency, an effect recently called "driven decoherence". By direct numerical solution of the time-dependent Schr\"odinger equation of the associated many-body system, we scrutinize the different mechanisms that may lead to this type of decoherence. Assuming the effects of dissipation to be negligible ($T_1=\infty$), it is shown that a system of dipolar-coupled spins with -- even weak-- random inhomogeneities is sufficient to explain the salient features of the experimental observations. Some experimental examples are given to illustrate the potential of the numerical simulation approach.