Universal Blind Quantum Computing with Weak Coherent Pulses

TL;DR

This paper introduces a practical approach to universal blind quantum computation using weak coherent pulses, enabling clients with realistic quantum devices to securely delegate quantum computations with approximate blindness.

Contribution

It proposes a protocol allowing clients with realistic quantum devices to achieve approximate blindness in UBQC using weak coherent pulses, relaxing ideal quantum state requirements.

Findings

The protocol achieves arbitrarily small security parameters.

Access to coherent states suffices for approximate blindness.

The approach enhances practicality of blind quantum computing implementations.

Abstract

The recently proposed Universal Blind Quantum Computation (UBQC) protocol allows a client to perform an arbitrary quantum computation on a remote server such that perfect privacy is guaranteed if the client is capable of producing random separable single qubit states. While from a theoretical point of view, this arguably constitutes the lowest possible quantum requirement, from a pragmatic point of view, generation of random single qubits which can be sent along long distances without loss is quite challenging and can never be achieved perfectly. In analogy to the concept of approximate security developed for other cryptographic protocols, we introduce here the concept of approximate blindness for UBQC, allowing us to characterize the robustness of the protocol to possible imperfections. Following this, we present a remote blind single qubit preparation protocol, by which a client with access to realistic quantum devices (such as coherent laser light) can in a delegated fashion prepare quantum states arbitrarily close to perfect random single qubit states. We finally prove that access to coherent states is sufficient to efficiently achieve approximate blindness with arbitrary small security parameter.