A Caltech Library Service

Towards a quantum network with atomic ensembles


Chou, Chin-wen (2006) Towards a quantum network with atomic ensembles. Dissertation (Ph.D.), California Institute of Technology.


The experiments discussed in this thesis investigate the application of atomic ensembles in building a quantum network. Specifically, the atomic ensembles refer to cesium atoms in magneto-optical traps. Chapter 1 gives an introduction to quantum networks, along with the difficulty in extending the range due to the optical loss of communication channels. Chapter 2 describes the protocol proposed by Duan, Lukin, Cirac, and Zoller (DLCZ) for overcoming the limit of channel loss on scaling up a quantum network, exploiting relatively simple setups with atomic ensembles. The protocol introduces many capabilities and simplifies many tasks in quantum information processing with atoms and light. Chapter 3 summarizes the first step in our lab toward realizing the DLCZ protocol. In particular, we observed nonclassical correlation between two optical fields generated from one atomic ensemble. Chapter 4 is a sidetrack apart from the DLCZ protocol. We demonstrated that the atomic ensemble can be used as a conditional source of single photons. In addition to a description of the experiment, details of the simple model we used to fit the data are also included. Chapter 5 augments chapter 4 in that the temporal behavior of the nonclassical correlation is investigated. We found that the correlation decayed rapidly, which is a major obstacle for further implementation of the DLCZ protocol. Chapter 6 describes our effort to fight the fast decay of correlation observed in the experiment. A theoretical model is used to better understand the source of decoherence. Chapter 7 is the follow-up in the direction of implementing the DLCZ protocol. Two atomic ensembles located in vacuum chambers on two optical tables are entangled in a heralded fashion. The details on controlling the phases of the interferometers and data processing are elaborated. Chapter 8 is a practical proposal on how to proceed further toward realization of the DLCZ protocol. Four atomic ensembles are involved in the proposed setup, which merely requires relative phase stability. Chapter 9 concludes the thesis and provides several possible directions toward building a large-scale quantum network through the DLCZ protocol.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:DLCZ; quantum entanglement; quantum repeater
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Physics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Kimble, H. Jeff
Thesis Committee:
  • Kimble, H. Jeff (chair)
  • Preskill, John P.
  • Vahala, Kerry J.
  • Painter, Oskar J.
  • Blatt, Rainer
Defense Date:22 May 2006
Record Number:CaltechETD:etd-05252006-185918
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:2059
Deposited By: Imported from ETD-db
Deposited On:31 May 2006
Last Modified:10 May 2017 23:09

Thesis Files

PDF (thesis.pdf) - Final Version
See Usage Policy.


Repository Staff Only: item control page