Long Distance Entanglement Between Quantum Memories (Springer Theses)

✍ Scribed by Yong Yu

• Publisher: Springer
• Tongue: English
• Leaves: 147
• Category: Library

✦ Synopsis

This book highlights novel research work done on cold atom-based quantum networks. Given that one of the main challenges in building the quantum network is the limited entanglement distribution distance, this book presents some state-of-the-art experiments in tackling this challenge and, for the first time, establishes entanglement between quantum memories via metropolitan-scale fiber transmission. This achievement is accomplished by cooperating high-efficiency cold quantum memories, low-loss quantum frequency conversion modules, and long-fiber phase-locking techniques. In the book, the scheme design, experimental setup, data analyses, and numerous technical details are given. Therefore, it suits a broad readership that includes all students, researchers, and technicians who work in quantum information sciences.

✦ Table of Contents

Supervisor’s Foreword
Abstract
Acknowledgements
Contents
1 Introduction
1.1 Fundamental of Quantum Information Processing
1.2 Entanglement-Based Cryptography
1.2.1 Ekert 91 Protocol
1.2.2 Quantum Teleportation
1.3 Quantum Repeater
1.4 Quantum Network
1.5 State of the Art
1.6 Structure of the Thesis
References
2 Principles of Quantum Memories
2.1 EIT Quantum Memory
2.1.1 Property Manipulation of the Optical Medium
2.1.2 EIT Quantum Memory
2.1.3 The Dynamic Process
2.2 DLCZ Quantum Memory
2.2.1 DLCZ Quantum Memory in Free Space
2.2.2 Cavity Enhanced DLCZ
2.3 Rydberg Blockade Mechanism
2.3.1 Rydberg Interaction
2.3.2 Rydberg Blockade
References
3 A High-Efficiency Quantum Memory
3.1 Preparation of Cold Atoms
3.1.1 Doppler Cooling
3.1.2 Magneto-Optical Trap
3.1.3 Polarization Gradient Cooling
3.1.4 Energy Diagram for Atomic Cooling
3.2 Energy Scheme for Quantum Memory Experiments
3.3 The Ring Cavity
3.3.1 Cavity Geometry
3.3.2 Cavity Locking
3.4 Quantum Memory Characterization
3.4.1 Quantum Correlation
3.4.2 Storage Efficiency and Lifetime
3.4.3 Entanglement Benchmarking
3.5 Comparison of the State-of-the-Art Quantum Memories
References
4 Quantum Frequency Conversion
4.1 Principle
4.1.1 Nonlinear Optics
4.1.2 Coupled Wave Equations
4.1.3 Quasi Phase Matching
4.2 Periodically Poled Lithium Niobate Waveguides
4.2.1 Generation of Periodic Poling
4.2.2 Waveguide Fabrication
4.2.3 Integrated QFC Chip
4.3 QFC Scheme
4.4 QFC Setup and Characterization
References
5 Remote Entanglement via the Two-Photon Scheme
5.1 Comparison of Two Entanglement Schemes
5.2 Experiment Setup
5.3 The Degree-of-Freedom Conversion of Photon Qubit
5.4 Field Deployed Fibres
5.5 Optimization of the Experiment Condition
5.6 Results for Remote Entanglement
5.7 Imperfection Analysis
References
6 Remote Entanglement via the Single-Photon Scheme
6.1 Experimental Setup
6.2 Phase Locking
6.2.1 Phase Locking Scheme
6.2.2 Suppression of Fast Phase Variation in Long Fibre Situation
6.2.3 Phase Uncertainty in PPLN Waveguide Chips and Atomic Ensembles
6.3 Benchmarking the Entanglement
6.4 Experimental Analysis
6.4.1 Imperfection of Photon Interference
6.4.2 Write-out Photon Mismatch
6.4.3 Phase Instability
6.4.4 Decrease of SNR
6.5 Lasers in Outdoor Applications
6.5.1 Phase of Control Lasers
6.5.2 Test Result
6.5.3 Statistics of Phase Fluctuation
References
7 Measurement-Device-Independent Verification of a Quantum Memory
7.1 The Theory of Measurement-Device-Independent Verification
7.2 Experimental Setup
7.3 Rydberg Single Photon Source
7.4 The EIT Quantum Memory
7.4.1 Specifications
7.4.2 Optimization of the Readout Profile
7.4.3 Phase Locking and the Losses in the Setup
7.5 Results
References
8 Further Improvement of Atomic Ensemble Quantum Memories
8.1 Entanglement Creation and Swapping via Rydberg Interactions
8.1.1 Quantum Circuits Representations for Operations in Rydberg Collective States
8.1.2 Deterministic Entanglement Generation
8.1.3 Intra-atom Entanglement Swapping
8.2 Raman Transition-Based Spinwave Operations
8.2.1 Long-Lived Storage of Qubits
8.2.2 The Configuration of Raman Beams in Ring Cavity Setup
8.2.3 Spinwave Echo-Based Multimode Quantum Memory
References
9 Conclusion and Outlook
References