Pathway Provided To Scalable Quantum Computer Architectures with NonLocal Quantum Gates
March 2003
One of the basic requirements for building a scalable quantum computer is the need
to interact arbitrary pairs of qubits (quantum bits) within the computer. However,
most quantum interactions have only a short range, limiting interactions between
qubits to those that are nearest neighbors. A chain of interactions between neighboring
qubits would be required to connect distant qubits, which would be a burdensome
communication cost.
In a recently submitted paper, David Song of the ITL Mathematical and COmputational
Sciences Division, along with Carl Williams and Gavin Brennen the NIST Physics Lab
have shown how one can efficiently solve this quantum communication problem
To do this, they propose the use of a set of ancillary
quantum bits to create a distant pair of entangled qubits. This entangled pair of atoms,
or quantum resource, then can be used to efficiently perform or teleport a nonlocal
quantum gate between any two distant qubits. The paper shows that this concept is robust
even in the presence of quantum noise and decoherence.
This new concept effectively provides a means of building a quantum bus, a concept very
similar to the classical bus connecting the basic architectural elements of the von Neumann
computer. Together with the key building blocks of a quantum computer, the quantum bus
provides a pathway to a scalable quantum architecture using nonlocal interactions.
