The effect of communication costs in solid-state quantum computing architectures

Abstract

Quantum computation has become an intriguing technology with which to attack difficult problems and to enhance system security. Quantum algorithms, however, have been analyzed under idealized assumptions without important physical constraints in mind. In this paper, we analyze two key constraints: the short spatial distance of quantum interactions and the short temporal life of quantum data.In particular, quantum computations must make use of extremely robust error correction techniques to extend the life of quantum data. We present optimized spatial layouts of quantum error correction circuits for quantum bits embedded in silicon. We analyze the complexity of error correction under the constraint that interaction between these bits is near neighbor and data must be propagated via swap operations from one part of the circuit to another.We discover two interesting results from our quantum layouts. First, the recursive nature of quantum error correction circuits requires a additional communication technique more powerful than near-neighbor swaps -too much error accumulates if we attempt to swap over long distances. We show that quantum teleportation can be used to implement recursive structures. We also show that the reliability of the quantum swap operation is the limiting factor in solid-state quantum computation.

Layered Architecture for Quantum Computing

“…Other researchers have proposed homogeneous systems built around this basic concept. One common structure is a recursive H tree, which works well with a small number of layers of a Calderbank-ShorSteane code, targeted explicitly at ion-trap systems [13,14]. Oskin et al [15], building on the Kane solid-state NMR technology [16], proposed a loose lattice of sites, explicitly considering the issues of classical control and movement of quantum data in scalable systems, but without a specific plan for QEC.…”

Architectural implications of quantum computing technologies

“…Kane has proposed a solid-state NMR system with excellent scalability, built on VLSI techniques for control [Kane 1998]; Oskin, Copsey et al have followed that work with engineering studies, suggesting that teleportation may be required to move qubits long distances even for error correction Copsey et al 2003], and progress in fabrication has been made [Clark et al 2003]. In this system, individual phosphorus atoms are embedded in a silicon substrate, and standard photolithography techniques are used to build control structures on the surface.…”

“…The first and most important class of these is the Calderbank-Shor-Steane (CSS) codes [Calderbank and Shor 1996;Shor 1996;Steane 1996;Preskill 1998b]. The theory and practice (including both experimental demonstrations [Chiaverini et al 2004;Pittman et al 2005;Roos et al 2004] and system design [Svore et al 2005;Steane 2002;Copsey et al 2003;Burkard et al 1999;Devitt et al 2004;Metodiev et al 2003;Szkopek et al 2004]) of QEC and FT operation are vast; we will not cover them in any depth here. Nevertheless, a basic understanding of the pressures that QEC and FT place on architecture is critical.…”

Tailoring quantum architectures to implementation style

“…Oskin et al proposed the use of quantum teleportation as a long-range on-chip communication mechanism [20], and it has since become a fundamental component of many QC architecture proposals including ion-trap [17] and solid-state QCs [5]. Isailovic et al detailed and evaluated an interconnection network based on quantum teleportation for ion-trap QCs [11].…”