Quantum Gates and Memory using Microwave Dressed States

TL;DR

This paper proposes a novel microwave dressing technique for trapped ions that significantly enhances coherence times, enabling scalable quantum information processing and quantum simulations by overcoming magnetic noise limitations.

Contribution

The paper introduces a theoretical and experimental method to extend coherence times of magnetic field sensitive states using microwave dressing, improving scalability of quantum systems.

Findings

Dressed states are long-lived with coherence times over 100 times longer.

Microwave dressing effectively mitigates magnetic noise effects.

The approach is applicable to various quantum systems suffering from magnetic noise.

Abstract

Trapped atomic ions have been successfully used for demonstrating basic elements of universal quantum information processing (QIP). Nevertheless, scaling up of these methods and techniques to achieve large scale universal QIP, or more specialized quantum simulations remains challenging. The use of easily controllable and stable microwave sources instead of complex laser systems on the other hand promises to remove obstacles to scalability. Important remaining drawbacks in this approach are the use of magnetic field sensitive states, which shorten coherence times considerably, and the requirement to create large stable magnetic field gradients. Here, we present theoretically a novel approach based on dressing magnetic field sensitive states with microwave fields which addresses both issues and permits fast quantum logic. We experimentally demonstrate basic building blocks of this scheme to show that these dressed states are long-lived and coherence times are increased by more than two orders of magnitude compared to bare magnetic field sensitive states. This changes decisively the prospect of microwave-driven ion trap QIP and offers a new route to extend coherence times for all systems that suffer from magnetic noise such as neutral atoms, NV-centres, quantum dots, or circuit-QED systems.