Quantum computation may seem to be a topic for science fiction, but small quantum computers have existed for several years and larger machines are on the drawing table. These efforts have been fueled by a tantalizing property: while conventional computers employ a binary representation that allows computational power to scale linearly with resources at best, quantum computations employ quantum phenomena that can interact to allow computational power that is exponential in the number of "quantum bits" in the system. Quantum devices rely on the ability to control and manipulate binary data stored in the phase information of quantum wave functions that describe the electronic states of individual atoms or the polarization states of photons. While existing quantum technologies are in their infancy, we shall see that it is not too early to consider scalability and reliability. In fact, such considerations are a critical link in the development chain of viable device technologies capable of orchestrating reliable control of tens of millions quantum bits in a large-scale system. The goal of this lecture is to provide architectural abstractions common to potential technologies and explore the systemslevel challenges in achieving scalable, fault-tolerant quantum computation. The central premise of the lecture is directed at quantum computation (QC) architectural issues. We stress the fact that the basic tenet of large-scale quantum computing is reliability through system balance: the need to protect and control the quantum information just long enough for the algorithm to complete execution. To architectQCsystems, onemust understand what it takes to design and model a balanced, fault-tolerant quantum architecture just as the concept of balance drives conventional architectural design. For example, the register file depth in classical computers is matched to the number of functional units, the memory bandwidth to the cache miss rate, or the interconnect bandwidth matched to the compute power of each element of a multiprocessor. We provide an engineering-oriented introduction to quantum computation and provide an architectural case study based upon experimental data and future projection for ion-trap technology.We apply the concept of balance to the design of a quantum computer, creating an architecture model that balances both quantum and classical resources in terms of exploitable parallelism in quantum applications. From this framework, we also discuss the many open issues remaining in designing systems to perform quantum computation.

Autorentext

Tzvetan S. Metodi is a senior member of the technical staff at the Computer Systems Research Department at the Aerospace Corporation. Tzvetan received his Bachelors degree in physics from the University of California at Davis and PhD in Computer Science also from UC Davis. Tzvetan's current effort in quantum computing focuses on the development of balanced architectural models of organization and specialization for emerging quantum computing technologies, incorporating quantum fault-tolerance and analysis using modern compilation techniques. His other research interests include the design of hardware-based secure partitioning techniques for general-purpose processors running multi-level security flight software systems employed on modern spacecraft. Frederic T. Chong is the director of Computer Engineering, the director of the Greenscale Center for Energy-Efficient Computing, and a professor of computer science at the University of California at Santa Barbara. Prof. Chong also leads the computer architecture and circuits areas in both the ORAQL and NGQCS projects under the IARPA Quantum Computer Science program. Prof. Chong also co-founded the Quantum Architecture Research Center (QARC) in 2001, which received the 2002 DARPATech most significant technical achievement award. Prof. Chong received his BS in 1990, MS in 1992, and PhD in 1996, all from MIT. He was an assistant professor at UC Davis from 1996-2001, was an associate professor at UC Davis from 2001-2005, and has been a professor at UCSB from 2005-present. Dr. Chong's research interests include quantum computing architectures, nanoscale electronics, embedded processing, computer security, and sustainable computing. Prof. Chong was a UC Davis Chancellor's Fellow (2002-2007) and received an NSF CAREER Award (1998-2002).