Universal protection of unitary evolution from slow noise: dynamical control pushed to the extreme

TL;DR

This paper introduces a method for universal control of quantum systems that simultaneously mitigates slow, constant noise, requiring at least a three-valued Hamiltonian, demonstrated through a two-qubit gate example.

Contribution

It presents a novel control technique that protects quantum evolution from first-order Hermitian noise using a minimal three-valued Hamiltonian.

Findings

The method achieves simultaneous control and noise compensation.

A specific control sequence for a two-qubit gate is numerically designed.

Protection against arbitrary Hermitian constant noise is demonstrated.

Abstract

We propose a technique that allows to simultaneously perform universal control of the evolution operator and compensate for the first order contribution of an arbitrary Hermitian constant noise. We show that, at least, a three-valued Hamiltonian is needed in order to protect the system against any such noise. This technique is illystrated by an explicit algorithm for a control sequence that is applied to numerically design a safe two-qubit gate.