Quantum Network with Multiple Cold Atomic Ensembles (Springer Theses)

✍ Scribed by Bo Jing

• Publisher: Springer
• Year: 2022
• Tongue: English
• Leaves: 197
• Category: Library

✦ Synopsis

This book highlights the novel research in quantum memory networking, especially quantum memories based on cold atomic ensembles. After discussing the frontiers of quantum networking research and building a DLCZ-type quantum memory with cold atomic ensemble, the author develops the ring cavity enhanced quantum memory and demonstrates a filter-free quantum memory, which significantly improves the photon-atom entanglement. The author then realizes for the first time the GHZ-type entanglement of three separate quantum memories, a building block of 2D quantum repeaters and quantum networks. The author also combines quantum memories and time-resolved measurements, and reports the first multiple interference of three single photons with different colors. The book is of good reference value for graduate students, researchers, and technical personnel in quantum information sciences.

✦ Table of Contents

Supervisor’s Foreword
Abstract
Preface
Acknowledgements
Contents
1 Introduction
1.1 Quantum Teleportation
1.2 Connection of Two Quantum Network Nodes
1.3 Connection of Multiple Quantum Network Nodes
1.4 Physical Realizations of Quantum Networks
1.5 State of the Art of Quantum Networks
1.6 Thesis Structure
References
2 Interaction Between Single Photons and Atomic Ensembles
2.1 Photon-Atom Interaction: Classical Description
2.1.1 Photon-Atom Interaction in Free Space
2.1.2 Photon-Atom Interaction Inside a Ring Cavity
2.2 Cavity Enhanced Photon-Atom Interaction: Quantum Theory
2.2.1 Jaynes-Cummings Model
2.2.2 Photon Scattering via the Atom Inside the Cavity
2.2.3 Interaction Between Photons and Atomic Ensembles Inside a Cavity
2.3 Summary
References
3 Preparation of Cold Atomic Ensembles
3.1 Vacuum System
3.2 Laser System
3.2.1 Lasers at 780 nm
3.2.2 Lasers at 795 nm
3.3 Magnetic Field
3.4 Magneto-Optical Trap
3.4.1 Fundamentals
3.4.2 Numbers of Atoms in MOT
3.5 Polarization Gradient Cooling
3.6 Cold Atomic Optical Depth and Temperature
3.6.1 Measurement of Optical Depth via Absorption Imaging
3.6.2 Measurement of Cold Atomic Temperature
3.7 Further Cooling of Cold Atoms
3.8 Summary
References
4 Highly Retrievable Quantum Memories
4.1 Background
4.2 DLCZ Quantum Memory and Its Quantization
4.2.1 The Write Process
4.2.2 The Read Process
4.2.3 EIT in the Read Process
4.2.4 Performance Criteria for Quantum Memory
4.2.5 Storage Lifetime
4.3 DLCZ Quantum Memory in the Free Space
4.3.1 Experimental Settings
4.3.2 Compensation of Environmental Magnetic Field
4.3.3 Initialization of Atomic States
4.3.4 Accidental Coincidence Events
4.3.5 Multi-excitation Events
4.4 DLCZ Quantum Memory with Ring Cavity Enhancement
4.4.1 Setup and Locking of the Ring Cavity
4.4.2 Phase Compensation of Cavity Wave Plates
4.4.3 Frequency of Cavity Locking Beam and Read Beam
4.4.4 Noise from the Cavity Locking Beam
4.4.5 Photonic Phase Shift Induced by Atoms
4.4.6 Cavity Finesse
4.4.7 Influence of Stability of Locked Cavity on Retrieval Efficiency
4.4.8 Influence of the Number of Experimental Trials on Retrieval Efficiency
4.4.9 Influence of Intensity of Read Beam on Retrieval Efficiency
4.4.10 Influence of Excitation Probability on Single Photon Quality Function α
4.4.11 Influence of Excitation Probability on Second-Order Correlation Function g2
4.5 DLCZ Quantum Memory with Atoms Initially Prepared in |F=1,mF=-1rangle
4.6 Summary
References
5 Entanglement of Three Cold Atomic Ensembles
5.1 Background
5.2 Entanglement Between Single Photons and Cold Atomic Ensembles
5.2.1 Photonic Polarization and Bias Magnetic Field
5.2.2 Accidental Coincidences
5.2.3 Raman Process
5.2.4 Multi-excitation Events
5.2.5 Initial State Purity
5.2.6 Photon-Atom Entanglement Fidelity
5.2.7 Efficiency of Photon-Atom Entanglement
5.3 Entanglement Between Two Cold Atomic Ensembles
5.3.1 Pulse Shape of Write Beam
5.3.2 Indistinguishability of Write-Out Photons
5.3.3 Imperfection of Polarization
5.3.4 From Photon-Atom Entanglement to Atom-Atom Entanglement
5.3.5 Experimental Results
5.4 Hybrid Entanglement of Three Cold Atomic Ensembles and Three Flying Photons
5.5 GHZ Entanglement of Three Cold Atomic Quantum Memories
5.6 Efficiency of Entanglement Generation and Verification
5.7 Summary
References
6 Interference of Three Frequency Distinguished Photons
6.1 Background
6.2 Single Photon Source
6.3 HOM Interference Between Two Indistinguishable Single Photons
6.4 Interference of Two Frequency Distinguished Photons
6.5 Interference of Three Frequency Distinguished Photons
6.5.1 Experimental Setup and Results
6.5.2 Fidelity Analysis
6.6 Summary
References
7 Entanglement of Two Cold Atomic Ensembles via 50 km Fibers
7.1 Background
7.2 Experimental Principle and Setup
7.3 Experimental Results
7.4 Summary
References
8 Summary and Outlook
Appendix A Saturated Absorption Spectrum for 87Rb D1 and D2 Line
Appendix B Calculation of Magnetic Field Generated by Rectangular Helmholtz Coils
Appendix C Retrieval Efficiency Under Different Polarization Combinations
Appendix D Fidelity Estimation of Bell State and GHZ State