IQC Special Seminar featuring Lukas Bödeker

Lukas Bödeker - Forschungszentrum Jülich and RWTH Aachen university 

Abstract: 

Quantum information is fragile: it is easily disturbed by noise, imperfect control, and unwanted interactions with the environment. To operate quantum devices reliably, one therefore needs methods that can protect encoded information, identify errors, and implement logical operations under realistic experimental constraints. 

In this talk, I will discuss several approaches to this problem. First, I will focus on decoding in active quantum error correction. I will show how neural networks can be trained to interpret measurement data, and how one can look inside these networks to test whether they have learned physically meaningful correction strategies. I will also discuss how experimental measurement data can be used directly to learn about the noise in a device and improve the decoding procedure. 

The second part of the talk focuses on logical operations between protected quantum bits. In particular, I will discuss lattice surgery, a method for combining and separating encoded qubits in order to create entanglement and teleport logical quantum states. The emphasis will be on how such protocols can be adapted to realistic superconducting-qubit hardware, where connectivity, measurement time, and classical feedback all affect performance. 

The final part takes a complementary viewpoint on the same question: instead of actively extracting measurement data and applying corrections, one can ask whether suitably engineered open quantum systems can protect and retrieve information through their own dynamics. I will discuss this idea in the context of quantum associative memories, where stored information is represented by stable states of a noisy driven system. This connects the active error-correction perspective to a broader question of how information can be stabilized in imperfect quantum devices. 

Location: QNC 0101