Microscopic Sources of Decoherence and Noise in Josephson Junction Qubits
Abstract
The Josephson junction (JJ) qubit is a leading candidate in the design of a quantum computer. A significant advantage of this approach is scalability, as these qubits may be readily fabricated in large numbers using integrated-circuit technology. A major obstacle to the realization of quantum computers with Josephson junction qubits is decoherence. The goal of our research was to elucidate the microscopic sources of this decoherence and to suggest ways to eliminate or reduce these culprits. We focused on the decoherence produced by two level systems in the insulating barrier of a Josephson junction as well as in the insulating dielectric material (e.g., SiO2) typically used to fabricate integrated circuit (IC) chips. Two level systems consist of an atom or group of atoms that can sit in one of two places. We worked with John Martinis' group (UCSB/NIST) which found that two level states are a dominant source of decoherence in superconducting qubits. One reason for this is that two level systems can resonantly absorb microwaves that are used to probe and manipulate the qubit. Once there are enough microwaves to saturate the two level systems, the rest of the microwaves can go through resulting in attenuation that decreases with increasing microwave power. Another mechanism for qubit decoherence is due to two level systems in the junction barrier which couple to the qubit. We explored two models in which a two level system couples to a qubit.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2008
- Accession Number
- ADA485322
Entities
People
- Clare C. Yu
Organizations
- University of California, Irvine