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arXiv:quant-ph/0509001 · Foundations of Quantum Mechanics in the Light of New Technology

LOCALLY OBSERVABLE CONDITIONS FOR THE SUCCESSFUL IMPLEMENTATION OF ENTANGLING MULTI-QUBIT QUANTUM GATES

HOLGER F. HOFMANN, RYO OKAMOTO, SHIGEKI TAKEUCHI

Published Jun 1, 2006• 0 citations
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Abstract

The information obtained from the operation of a quantum gate on only two complementary sets of input states is sufficient to estimate the quantum process fidelity of the gate. In the case of entangling gates, these conditions can be used to predict the multi qubit entanglement capability from the fidelities of two non-entangling local operations. It is then possible to predict highly non-classical features of the gate such as violations of local realism from the fidelities of two completely classical input-output relations, without generating any actual entanglement.

DOI
10.1142/9789812773210_0016

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The information obtained from the operation of a quantum gate on only two complementary sets of input states is sufficient to estimate the quantum process fidelity of the gate. In the case of entangling gates, these conditions can be used to predict the multi qubit entanglement capability from the fidelities of two non-entangling local operations. It is then possible to predict highly non-classical features of the gate such as violations of local realism from the fidelities of two completely classical input-output relations, without generating any actual entanglement.
The information obtained from the operation of a quantum gate on only two complementary sets of input states is sufficient to estimate the quantum process fidelity of the gate. In the case of entangling gates, these conditions can be used to predict the multi qubit entanglement capability from the fidelities of two non-entangling local operations. It is then possible to predict highly non-classical features of the gate such as violations of local realism from the fidelities of two completely classical input-output relations, without generating any actual entanglement.
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Quantum entanglement, a fundamental phenomenon in quantum mechanics, presents a unique challenge to traditional computational methods. This paper explores the potential of utilizing entanglement to enhance quantum computation, specifically focusing on the development of a novel prediction algorithm predicated on the non-local nature of entangled states. We propose a method that leverages the inherent properties of entanglement to predict the state of quantum systems with improved accuracy. This research aims to address limitations in current quantum algorithms by providing a new approach to quantum state determination. The core mechanism involves the construction of a predictive model, utilizing entanglement's non-classical behavior, to accurately forecast quantum system properties. This work explores the potential implications of this algorithm for enhancing quantum computing capabilities and highlights its unique advantages.
Accurate characterization of two-qubit gates will be critical for any realization of quantum computation. We discuss a range of measurements for characterizing two-qubit gates. These measures are architecture-independent and span a range of complexity from simple measurement routines to full quantum-state and process tomography. Simple indicative measures, which flag but do not quantify gate operation in the quantum regime, include the fringe visibility, parity, Bell-state fidelity, and entanglement witnesses. Quantitative measures of gate output states include linear entropy and tangle; measures of, and error bounds to, whole-gate operation are provided by metrics such as process fidelity, process distance, and average gate fidelity. We discuss which measures are appropriate, given the stage of development of the gate, and highlight connections between them.
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