Kae Nemoto

Measurement-induced nonlinearity in linear optics

We investigate the generation of nonlinear operators with single-photon sources, linear optical elements, and appropriate measurements of auxiliary modes. We provide a framework for the construction of useful single-mode and two-mode quantum gates necessary for all-optical quantum information processing. We focus our attention generally on using minimal physical resources while providing a transparent and algorithmic way of constructing these operators.

Communication Links for Distributed Quantum Computation

Distributed quantum computation requires quantum operations that act over a distance on error correction-encoded states of logical qubits, such as the transfer of qubits via teleportation. We evaluate the performance of several quantum error correction (QEC) codes and find that teleportation failure rates of one percent or more are tolerable when two levels of the [[23, 1, 7]] code are used. We present an analysis of performing QEC on QEC-encoded states that span two quantum computers, including the creation of distributed logical zeros. The transfer of the individual qubits of a logical state may be multiplexed in time or space, moving serially across a single link or in parallel across multiple links. We show that the performance and reliability penalty for using serial links is small for a broad range of physical parameters, making serial links preferable for a large, distributed quantum multicomputer when engineering difficulties are considered. Such a multicomputer will be able to factor a 1,024-bit number using Shors algorithm with a high probability of success.