Towards qubit noise spectroscopy by quantum bang-bang control

Quantum bang-bang control is a method of suppressing decoherence in qubits [VKL99, VL98]. To date, mathematically rigorous treatments of quantum bang-bang control offered little intuition. To complement existing approaches and to seek better understanding, I present intuitive pictures to think about quantum bang-bang control. In addition, I develop a formalism for treating phase noise moments of a qubit under quantum bang-bang control. Although the desired purpose of quantum bang-bang control is to remove noise, it is conceivable that it can be used to infer information about the noise process and coupling on a qubit. By using a simple random rotation model of single qubit dephasing, I demonstrate how quantum bang-bang control can distinguish between dephasing under different stochastic processes. I also show how quantum bang-bang control can determine noise coupling in a toy model where noise couples to the qubit via a fixed noise axis. These two demonstrations indicate the potential of quantum bang-bang control as a tool for qubit noise spectroscopy.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Physics.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2004

Author dc:creator

• Chen, Zilong, 1981-

Advisor dc:contributor.advisor

• Isaac L. Chuang.

• Physics.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/32721

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/32721