Enhancing quantum control by improving shape pulse generation

TL;DR

This paper introduces a scalable, efficient algorithm for designing optimized pulse sequences to control quantum states, demonstrated through NMR experiments on systems up to 12 qubits and simulations on larger lattices.

Contribution

It presents a novel, parameter-efficient algorithm for quantum pulse design that improves speed and scalability over existing methods.

Findings

Successful implementation on 4, 7, and 12 qubits using NMR.

Effective control of large spin systems with up to 100 qubits.

Reduced computational complexity with fewer parameters.

Abstract

Most quantum processors requires pulse sequences for controlling quantum states. Here, we present an alternative algorithm for computing an optimal pulse sequence in order to perform a specific task, being an implementation of a quantum gate or a quantum state preparation. In our method, we reduced drastically the number of parameters to be fitted, by using a limited number of functions as the modulations for the amplitude and phase of the radio-frequency pulses, and employed approximations to make the algorithm fast and scalable. We demonstrate the success of the proposed algorithm, by performing several real experiments for 4, 7 and 12 quantum bits systems using NMR. In addition, we have also shown the efficiency of the algorithm, finding pulses for controlling with good fidelity the quantum states of spins in a fictional square bi-dimensional lattices containing 16, 36 and 100 qubits.