Experimental Quantum Computing without Entanglement

2008/07/04 by B. P. Lanyon, M. Barbieri, Marco Barbieri +2 · 13 citations
Computer Science · Physics and Astronomy · #Algorithm #Computation #Computer science #Neural Networks and Reservoir Computing #Open quantum system #Parallel computing #Physics #Quantum #Quantum Computing Algorithms and Architecture #Quantum Information and Cryptography #Quantum capacity #Quantum computer #Quantum discord #Quantum entanglement #Quantum information #Quantum mechanics #Quantum network #Quantum technology #Qubit #Separable state #Speedup #Statistical physics #quant-ph

paper · pdf · doi:10.1103/physrevlett.101.200501

published as Physical Review Letters 101, 200501 (2008) · 5 pages, 4 figures

arxiv created 2008/07/04 · openalex publication_date 2008/11/13 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

Abstract

Deterministic quantum computation with one pure qubit (DQC1) is an efficient model of computation that uses highly mixed states. Unlike pure-state models, its power is not derived from the generation of a large amount of entanglement. Instead it has been proposed that other nonclassical correlations are responsible for the computational speedup, and that these can be captured by the quantum discord. In this Letter we implement DQC1 in an all-optical architecture, and experimentally observe the generated correlations. We find no entanglement, but large amounts of quantum discord-except in three cases where an efficient classical simulation is always possible. Our results show that even fully separable, highly mixed, states can contain intrinsically quantum mechanical correlations and that these could offer a valuable resource for quantum information technologies.

Citations

• Role of entanglement and correlations in mixed-state quantum computation
• Optical Quantum Computing
• Photon statistics characterization of a single-photon source
• Exponential Speedup with a Single Bit of Quantum Information: Measuring the Average Fidelity Decay
• Classical, quantum and total correlations
• On the role of entanglement in quantum-computational speed-up
• Distributed Entanglement

Cited by

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• CREATING QUANTUM DISCORD THROUGH LOCAL GENERALIZED AMPLITUDE DAMPING
• Quantum correlation measure in arbitrary bipartite systems
• Optimal measurements to access classical correlations of two-qubit states
• Gaussian continuous-variable isotropic state
• Homodyne Estimation of Gaussian Quantum Discord
• Quantum correlations and distinguishability of quantum states
• Overarching framework between Gaussian quantum discord and Gaussian quantum illumination
• Correlations in the Grover search
• Non-commutative measure of quantum correlations under local operations
• Problem of quantifying quantum correlations with non-commutative discord