Adding control to arbitrary unknown quantum operations

TL;DR

This paper introduces a universal, architecture-independent method for adding control qubits to any quantum operation, simplifying implementation in quantum algorithms and experiments.

Contribution

The authors present a novel technique that enables control of arbitrary quantum operations without prior knowledge of the operation, independent of the underlying implementation.

Findings

Successfully demonstrated the method in a photonic system

Achieved high-fidelity two-qubit gates using the technique

The approach is versatile and applicable to various quantum algorithms

Abstract

While quantum computers promise significant advantages, the complexity of quantum algorithms remains a major technological obstacle. We have developed and demonstrated an architecture-independent technique that simplifies adding control qubits to arbitrary quantum operations-a requirement in many quantum algorithms, simulations and metrology. The technique is independent of how the operation is done, does not require knowledge of what the operation is, and largely separates the problems of how to implement a quantum operation in the laboratory and how to add a control. We demonstrate an entanglement-based version in a photonic system, realizing a range of different two-qubit gates with high fidelity.