Readout of relaxation rates by nonadiabatic pumping spectroscopy

TL;DR

This paper introduces a nonadiabatic charge pumping method to accurately measure charge relaxation rates in quantum dot systems, enabling improved control for quantum devices and metrology applications.

Contribution

It presents a novel nonadiabatic pumping spectroscopy technique that reliably measures relaxation rates without fitting parameters, applicable to quantum dots and dopant systems.

Findings

Reliable readout of relaxation rates from current plateaus

Method is independent of fitting parameters

Applicable to quantum dots and dopant systems

Abstract

We put forward nonadiabatic charge pumping as a method for accessing the different charge relaxation rates as well as the relaxation rates of excited orbital states in double-quantum-dot setups, based on extremely size-limited quantum dots and dopant systems. The rates are obtained in a well-separated manner from plateaus, occurring when comparing the steady-state current for reversed driving cycles. This yields a reliable readout independent of any fitting parameters. Importantly, the nonadiabatic pumping spectroscopy essentially exploits the same driving scheme as the operation of these devices generally employs. We provide a detailed analysis of the working principle of the readout scheme as well as of possible errors, thereby demonstrating its broad applicability. The precise knowledge of relaxation rates is highly relevant for the implementation of time-dependently operated devices, such as electron pumps for metrology or qubits in quantum information.