We address the challenge of designing a quantum computer architecture with a layered framework that is modular and facilitates fault-tolerance. The framework is flexible and could be used for analysis and comparison of differing quantum computer designs. Using this framework, we develop a complete, layered architecture for quantum computing with optically controlled quantum dots, showing how a myriad of technologies must operate synchronously to achieve fault-tolerance. Our design deliberately takes advantage of the large possibilities for integration afforded by semiconductor fabrication. Quantum information is stored in the electron spin states of a charged quantum dot controlled by ultrafast optical pulses. Optical control makes this system very fast, scalable to large problem sizes, and extensible to quantum communication or distributed architectures. The design of this quantum computer centers on error correction in the form of a topological surface code, which requires only local and nearest-neighbor gates. We analyze several important issues of the surface code that are relevant to an architecture, such as resource accounting and the use of Pauli frames. Furthermore, we investigate the performance of this system and find that Shor's factoring algorithm for a 2048-bit number can be executed in approximately one week.
Figure 1. Layered framework for a quantum computer architecture. Each layer contains a set of duties which are essential for the quantum computer to function properly. The organization of the layers promotes a fault-tolerant and modular design.
Figure 2. The central control cycle of a quantum computer. Because quantum information is short-lived, control operations must be pipelined for efficiency. Managing the large quantity of classical data is itself a challenging engineering problem.
N. Cody Jones, Rodney Van Meter, Austin G. Fowler, Peter L. McMahon, Jungsang Kim, Thaddeus D. Ladd, and Yoshihisa Yamamoto, "A Layered Architecture for Quantum Computing Using Quantum Dots," arXiv:1010.5022
Dr. Thaddeus Ladd
Prof. Yoshihisa Yamamoto
Prof. Rodney Van Meter (Keio University, Japan) [Group Website]
Dr. Austin Fowler (Unversity of Melbourne, Australia)
Prof. Jungsang Kim (Duke University)
National Science Foundation (Project #0829694)