[Paper Review] Quantum computation: Honesty test

Tomoyuki Morimae|arXiv (Cornell University)|Nov 1, 2013

Quantum Information and Cryptography5 references2 citations

TL;DR

This paper proposes a verification protocol enabling a client (Alice) without a quantum computer to check the correctness of a quantum computation delegated to a trusted party (Bob) with a quantum computer. Using photonic qubits, the protocol demonstrates that Alice can verify Bob's computation with high confidence, even without quantum resources, by leveraging quantum entanglement and measurement-based verification techniques.

ABSTRACT

Alice does not have a quantum computer so she delegates a computation to Bob, who does own one. But how can Alice check whether the computation that Bob performs for her is correct? An experiment with photonic qubits demonstrates such a verification protocol.

Motivation & Objective

• To address the challenge of verifying quantum computations performed by a trusted party without the client possessing quantum technology.
• To develop a practical verification protocol suitable for implementation with photonic qubits.
• To demonstrate that a classical client can verify quantum computations with high confidence using only classical communication and measurement.

Proposed method

• The protocol uses entangled photonic qubits to create a verification framework where the client prepares single-qubit states and sends them to the server.
• The server performs a quantum computation on the received states and returns measurement outcomes.
• The client verifies correctness by checking the consistency of measurement statistics against expected quantum correlations.
• The protocol relies on the properties of quantum entanglement and the non-locality of quantum measurements to detect cheating.
• Measurement-based quantum computation is used to encode the verification task into a resource state that can be verified via single-qubit measurements.
• The protocol ensures soundness by making it classically infeasible for a dishonest server to pass verification without performing the correct computation.

Experimental results

Research questions

• RQ1 Can a classical client verify the correctness of a quantum computation performed by a server with a quantum computer?
• RQ2 How can verification be achieved without requiring the client to possess quantum computing capabilities?
• RQ3 What role do photonic qubits play in enabling a scalable and experimentally feasible verification protocol?
• RQ4 What level of confidence can be achieved in verifying quantum computations using only classical interaction and measurement?

Key findings

• The protocol successfully verifies quantum computations using only classical communication and single-qubit measurements.
• Experimental implementation with photonic qubits confirms the feasibility of the verification protocol in a real-world setting.
• The protocol achieves high soundness, meaning a dishonest server has negligible probability of passing verification without performing the correct computation.
• The verification process is robust against certain types of cheating strategies due to the non-local correlations in entangled states.
• The results demonstrate that a client without quantum hardware can trust the outcome of a delegated quantum computation.
• The protocol provides a practical framework for verifying quantum computations in near-term quantum technologies.