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Experimental verification of quantum computation


Quantum computers are expected to offer substantial speed-ups over their classical counterparts and to solve problems intractable for classical computers. Beyond such practical significance, the concept of quantum computation opens up fundamental questions, among them the issue of whether quantum computations can be certified by entities that are inherently unable to compute the results themselves. Here we present the first experimental verification of quantum computation. We show, in theory and experiment, how a verifier with minimal quantum resources can test a significantly more powerful quantum computer. The new verification protocol introduced here uses the framework of blind quantum computing and is independent of the experimental quantum-computation platform used. In our scheme, the verifier is required only to generate single qubits and transmit them to the quantum computer. We experimentally demonstrate this protocol using four photonic qubits and show how the verifier can test the computer’s ability to perform quantum computation.

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Figure 1: Concept of a quantum prover interactive proof system based on blind quantum computing.
Figure 2: Measurement verification.
Figure 3: Schematic of a quantum computation with verification sub-routines.
Figure 4: A blind Bell test for the verification of quantum resources.

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The authors are grateful to S. Aaronson, D. Aharonov, C. Brukner, A. Zeilinger and F. Verstraete for discussions. S.B. and P.W. acknowledge support from the European Commission, Q-ESSENCE (No. 248095), QUILMI (No. 295293), EQUAM (No. 323714), PICQUE (No. 608062) and the ERA-Net CHISTERA project QUASAR, the John Templeton Foundation, the Vienna Center for Quantum Science and Technology (VCQ), the Austrian Nano-initiative NAP Platon, the Austrian Science Fund (FWF) through the SFB FoQuS (No. F4006-N16), START (No. Y585- N20) and the doctoral programme CoQuS, the Vienna Science and Technology Fund (WWTF) under grant ICT12-041, and the Air Force Office of Scientific Research, Air Force Material Command, United States Air Force, under grant number FA8655-11-1-3004. J.F.F. acknowledges support from the National Research Foundation and the Ministry of Education, Singapore. This material is based on research supported in part by the Singapore National Research Foundation under NRF Award No. NRF-NRFF2013-01. E.K. acknowledges support from UK Engineering and Physical Sciences Research Council (EP/E059600/1).

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S.B. designed and performed the experiments, acquired the experimental data, carried out theoretical calculations and the data analysis, and wrote the manuscript. J.F.F. and E.K. carried out theoretical calculations, contributed the proofs, and wrote the manuscript. P.W. designed the experiment, edited the manuscript and supervised the project.

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Correspondence to Stefanie Barz or Philip Walther.

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The authors declare no competing financial interests.

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Barz, S., Fitzsimons, J., Kashefi, E. et al. Experimental verification of quantum computation. Nature Phys 9, 727–731 (2013).

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