Algorithms on Ensemble Quantum Computers

TL;DR

This paper develops modifications to key quantum algorithms to enable their execution on ensemble quantum computers, which can only measure expectation values rather than individual qubits.

Contribution

It introduces adaptations of universal fault-tolerant computation, Shor's algorithm, and search algorithms for ensemble quantum computing models.

Findings

Modified algorithms successfully adapt to measurement limitations

Enables implementation of complex algorithms on ensemble quantum computers

Extends the applicability of quantum algorithms to new hardware constraints

Abstract

In ensemble (or bulk) quantum computation, measurements of qubits in an individual computer cannot be performed. Instead, only expectation values can be measured. As a result of this limitation on the model of computation, various important algorithms cannot be processed directly on such computers, and must be modified. We provide modifications of various existing protocols, including algorithms for universal fault--tolerant computation, Shor's factorization algorithm (which can be extended to any algorithm computing an NP function), and some search algorithms to enable processing them on ensemble quantum computers.