Soutenance d'Hector Hutin
| When |
Nov 29, 2024
from 02:00 to 03:00 |
|---|---|
| Where | Salle des thèses |
| Contact Name | Hector Hutin |
| Attendees |
Hector Hutin |
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The association of a quantum bit and a harmonic mode dispersively coupled is one of the most studied systems in the field of quantum electrodynamics of superconducting circuits. It offers one of the most reliable current methods for measuring the state of a quantum bit in a non-destructive manner and has enabled numerous quantum information experiments, studying the information obtained through this measurement and the dynamics of the qubit when subjected to it. It also provides the ability to prepare and manipulate the quantum state of the harmonic mode via the qubit, allowing information to be stored and processed in this mode, which is fundamental to building a quantum processor. This thesis presents two experiments based on this architecture.
The first demonstrates how to use qubit fluorescence to non-destructively read the number of photons contained in a microwave cavity in a single shot, that is, before the cavity has relaxed. This makes it possible to measure photon number trajectories and observe them leave the cavity one by one. The analysis of this experiment relies on a fluorescence analysis in terms of propagating modes and addresses a number of questions about the information that these modes may contain.
The second is a demonstration of the use of a neural network for quantum state preparation in the cavity. Here, the goal is to accelerate the optimization of control electromagnetic pulses at the frequencies of the cavity and qubit to create a quantum state in the cavity with high fidelity, and this for a broad class of states. To evaluate the efficiency of this new optimization protocol over this class of states, an optimal method to assess the fidelity of the prepared states using a Wigner function measurement protocol was experimentally implemented for the first time.