Objectives:

Quantum Information Science (QIS) is a very new emerging research and education frontier that has generated a great deal of interest and stimulated novel potential applications in the last few years. It combines and draws on the disciplines of physical science, mathematics, computer science, and engineering. Its aim is to understand how certain fundamental laws of quantum physics can be harnessed to dramatically improve the storage, processing and transmission of information. Quantum physics, information theory, and computer science are among the crowning intellectual achievements of the past century.

The QIS focus program supported by National Center for Theoretical Science will build a platform of communication for researchers in this area. We have established associations and cooperation other researchers all over Taiwan; and will seek to establish links and exchanges other QIS researchers and activities worldwide. We believe this national program will be joined by many other local researchers in the near future. Although Taiwan has yet to make its mark on the subject internationally, many local researchers are already working on areas bordering on QIS, both theoretically and experimentally. We believe with strong support and encouragement; with the appropriate alignment of theoretical and experimental personnel, by learning from others, by exchanging scholars and information with other institutions; and last but not least - by closely integrating QIS research with Taiwan’s commitment, we will be able to ramp up quickly to realize Taiwan’s potential in QIS, and to compete on equal footing with other nations in this exciting frontier.

To achieve the above objectives, a program committee has been formed for the year of 2005. Its mission includes selection of research topics, budget allocation, and invitation of long-term visitors and recommendation of candidates for exchange programs. The current members and their specializations are:

 

Wei-Min Zhang (NCKU), quantum dot quantum computers (Theory)

Hsi-Sheng. Goan (NTU), silicon-based quantum computer, decoherence (Theory)

Chih Long Chou (CYCU), quantum communication (Theory)

Pochung Chen (NTHU), quantum dot quantum computer (Theory)

Der-San Chuu (NCTU), cavity QED, quantum dot (Theory & Experiment)

Zheng-Yao Su (NCHC), quantum algorithms (Theory)

Chopin Soo (NCKU) quantum entanglement, fundamental quantum physics (Theory)

The committee meeting will be held once every two month. The first committe meeting was in April at National Cheng Kung University. The Second committe meeting held in June at National Taiwan University.

 

Outlines of Activities:

With the budget of about 2 million TWD for the academic year 2004-2005, the committee has decided to support for a post-doc researching position. This position had granted to Dr. Lee, Min-Chung. He is current working on the theory of decoherence process.

In order to provide a communication platform from QIS researchers in Taiwan, we plan to have a small workshop every two months. The first workshop was held on June 10 and 11 at national Taiwan University, hosted by Hsi-Sheng Goan. The second workshop was held in September 23 at National Tsing Hwa University. Pochung Chen and Zeng-Yao Su hosted this workshop.

We are planning a QIS winter school in December 2005. The list of candidates of inviting speakers including Prof. Lu Jeu Sham (UC San Diego, USA), Prof. Hoi-Kwong Lo (U. Toronto, Canada), Prof. Bei Lok Hu (U. Maryland, USA), Prof Artur Ekert (NUS, Singapore) and Prof. Francesco Petruccione (South Africa).

 

Progresses:

1. The first workshop was held on Jun 10 – 11 at National Taiwan University hosted by Hsi-Sheng Goan. The inviting speakers and their topics were:

The following shows the speakers and part of the participants of this workshop.

 

2. The second workshop was held on September 23 at National Tsing Hua University hosted by Pochung Chen and Zeng-Yao Su . The inviting speakers and their topics were:

 

3. Seminars on QIS held in NCTS/South

Date Speaker Title

2005/02/22

Prof. Min-Sheng Wang
Department of Physics, National Central University

Validity of the postulates of quantum mechanics - A study based on von Neumann measurement theory

2005/03/07

Prof. Ite Albert Yu
Department of Physics, National Tsing Hua University

Storage and retrieval of photonic information - from electromagnetically induced transparency to reduction of the light speed

2005/03/14

Prof. Shun-Jen Cheng
Department of ElectroPhysics, National Chiao Tung University

Excitonic artificial atoms: Photoexcited self-assembled semiconductor quantum dots

2005/03/16

Photon Entanglement Topical Discussion

Three Photon Entanglement

2005/03/21

Prof. Chuan-Pu Liu
Department of Material Science and Engineering, NCKU

QIS group meeting on Quantum Dots experiments

2005/03/22

Photon Entanglement Topical Discussion

The properties of optical components for preparing an
entanglement photon pair

2005/03/23

Prof. Zheng-Yao Su
National Center for High-performance Computing

QIS Theory Group Discussion : Algebraic invariants their applications in QIS

2005/03/28

Prof. Chi-Shung Tang
National Center for Theoretical Sciences

From Dynamical Transport to Spin Quantum Bits

2005/03/29

Photon Entanglement Topical Discussion

Entanglement Photon from femtosecond laser

2005/04/11

張文豪 博士
Department of Physics, National Central University

Single-mode single-photon sources based on single quantum dots in photonic crystal nanocavities

2005/04/18

Quantum Dots Group Meeting

The latest experimental progress

2005/04/19

劉如芬 同學
Department of Physics, NCKU

Photon Entanglement Topical Discussion : Introduction to mixed state entanglement - the basic

2005/04/26

Prof. Po-Chung Chen
Department of Physics, National Tsing Hua University

Dynamical Decoupling for Pedestrians

2005/05/02

Dr. Shu-Hui Tsai
Institute of Physics, Academia Sinica

Noise measurement in qubits readout

2005/05/03

Photon Entanglement Topical Discussion
Department of Physics, NCKU

Current status of photon down-conversion

2005/05/16

Prof. Ikai Lo
Department of Physics, National Sun Yat-Sen University

Application of GaN-based Semiconductors in Spintronics: Spin-polarized Field Effect Transistor

2005/05/23

Prof. Watson Kuo
Department of Physics, National Chung Hsing University

Toward single charge detection

2005/05/30

Prof. Hsi-Sheng Goan
Department of Physics, National Taiwan University

Quantum Technology

2005/06/06

QIS Group Meeting :林俊鈺同學
Department of Physics, NCKU

Decomposition of the Density Matrix

2005/06/13

Prof. Bei-Lok Hu
University of Maryland

Non-Markovian Decoherence and Error Prevention by Dynamical Decoupling

2005/06/20

Prof. Todd Brun
University of Southern California

Quantum trajectories and the flow of information

2005/06/29

Quantum Dots Group Meeting

Quantum Dots Group Meeting

2005/09/19

Prof. Pi-Gang Luan
Institute of Optical Sciences, National Central University

Anomalous refraction in photonic crystals

2005/09/21

Quantum Dots Group Meeting

The latest experimental progress

2005/09/26

Prof. Wei-Min Zhang
Department of Physics, NCKU

Free Spin Quantum Computer

2005/10/03

Dr. Ying-Cheng Chen
Institute of Atomic and Molecular Sciences, Academia Sinica

Exploring the ultracold world

2005/10/13

Prof. Jaw-Shen Tsai
Laboratory Head, Macroscopic Quantum Coherence Lab, Riken; & Research Fellow, Fundamental Research Laboratories, NEC, Japan

Josephson Multi-Qubit Systems

 

 

4. “Quantum Decoherence in Solid-state qubits” Reseach report by Ming Tsung Lee

My research interests are primarily in the related field of quantum information physics containing: Physical realizations of quantum information, mechanism and control of quantum decoherence, and quantum measurement. This field has attracted much attention for practical applications in quantum information science in recent years. Quantum decoherence is mainly induced by the interaction of a microscopic system coupled with its environment. The non-unitary evolution of the system destroys the purity of quantum states, quantum interference and quantum entanglement, and leads to information loss toward the environment.

Recently, some investigations of quantum decoherence have been focused on the decoherence induced by quantum measurements and the controls of quantum decoherence. For the implementation of realistic quantum information processors, these studies become the most champion works in the field. In the solid-state quantum computer with charge qubits, qubit measurements can be realized by the charge qubit coupled with sensitive electrometers such as quantum point contacts (QPC) and single-electron transistors. I have been researching on the quantum measurement of a single-electron in coupled quantum dots (a charge qubit) by a QPC and the dynamical non-equilibrium effect of the QPC on the decoherence of the charge qubit.

To study the quantum decoherence induced by quantum measurement, the condition of the perfect heat bath is usually introduced to simplify the problem in literatures. However, practically, this condition is not guaranteed at mesoscopic scale. The non-equilibrium effect from the heat bath should be taken into account. For the QPC, the non-equilibrium effect could be induced by the electron accumulation (EA) in reservoirs. I have developed a perturbation scheme to take the EA effect into account [1]. The character of the EA in terms of the analytic EA number and the quantum decoherence of the measured single electron in coupled dots under the EA effect are studied in the framework. The theory shows that the EA can induce an extra relaxation to the qubit decoherence. However, the influence of the EA effect to the decoherence rate depends on the bias-assistance in the QPC.

 

 

Committee member of focused group:

Hsi-Sheng Goan National Taiwan Univ .
Wei-Min Zhang(coordinator) National Cheng Kung Univ.
Pochung Chen National Tsing Hua Univ .
Der-San Chuu Nat'l Chiao Tung Univ.
Chopin Soo National Cheng Kung Univ.
Chih Long Chou Chung Yuan Christian Univ.
Zheng-Yao Su National Center for High-Performance Computing