Hybrid quantum computing with ancillas

TL;DR

This paper reviews how ancilla systems can be used in quantum computing to mediate interactions, enhance data protection, and implement efficient quantum gates, crucial for building practical quantum computers.

Contribution

It provides a comprehensive overview of ancilla-mediated quantum operations and their role in the gate model architecture for quantum computing.

Findings

Ancilla systems enable interaction between separated quantum registers.

Using fresh ancillas helps preserve quantum data integrity.

Ancilla-mediated operations facilitate efficient quantum gate implementation.

Abstract

In the quest to build a practical quantum computer, it is important to use efficient schemes for enacting the elementary quantum operations from which quantum computer programs are constructed. The opposing requirements of well-protected quantum data and fast quantum operations must be balanced to maintain the integrity of the quantum information throughout the computation. One important approach to quantum operations is to use an extra quantum system - an ancilla - to interact with the quantum data register. Ancillas can mediate interactions between separated quantum registers, and by using fresh ancillas for each quantum operation, data integrity can be preserved for longer. This review provides an overview of the basic concepts of the gate model quantum computer architecture, including the different possible forms of information encodings - from base two up to continuous variables - and a more detailed description of how the main types of ancilla-mediated quantum operations provide efficient quantum gates.