[Paper Review] Toward The Universal Quantum Cloner Limit For Designing Compact Photonic CNOT Gate

Amor Gueddana, Vasudevan Lakshminarayanan|arXiv (Cornell University)|Jun 15, 2019

Quantum Information and Cryptography8 references4 citations

TL;DR

This paper proposes a near-deterministic, compact photonic CNOT gate using a quantum dot in a double-sided optical microcavity, leveraging a universal quantum cloner to surpass the 5/6 fidelity limit. It achieves a fidelity of approximately 91% in the weak coupling regime, demonstrating a scalable approach for photonic quantum computing with high efficiency and robustness.

ABSTRACT

We suggest a near deterministic compact model of a photonic CNOT gate based on a quantum dot trapped in a double sided optical microcavity and a universal cloner. Our design surpasses the cloner optimal limit of 5/6 and we show that it provides fidelity around 91 % in the weak coupling regime.

Motivation & Objective

• To design a compact, scalable photonic CNOT gate suitable for integrated quantum photonic circuits.
• To overcome the fidelity limit of 5/6 imposed by universal quantum cloners in photonic quantum gate implementations.
• To achieve high-fidelity quantum gate operation in the weak coupling regime using a quantum dot-microcavity system.
• To demonstrate that the proposed design exceeds the theoretical cloner limit, enabling near-deterministic operation.
• To provide a practical, experimentally feasible architecture for photonic quantum computation with high fidelity.

Proposed method

• Utilizes a quantum dot embedded in a double-sided optical microcavity to mediate photon-photon interactions.
• Employs a universal quantum cloner as a core component to enhance gate fidelity beyond the 5/6 theoretical limit.
• Operates in the weak coupling regime to reduce decoherence and maintain high fidelity.
• Models the system using quantum optical techniques to simulate gate performance and fidelity.
• Analyzes the gate operation through fidelity metrics derived from quantum process tomography principles.
• Optimizes the cavity-QED system parameters to maximize gate fidelity under realistic experimental constraints.

Experimental results

Research questions

• RQ1 Can a photonic CNOT gate be designed to surpass the 5/6 fidelity limit imposed by universal quantum cloners?
• RQ2 What is the achievable fidelity of a compact photonic CNOT gate using a quantum dot in a double-sided microcavity?
• RQ3 How does operation in the weak coupling regime affect gate fidelity and scalability?
• RQ4 To what extent can quantum dot-microcavity systems enable near-deterministic photonic quantum gates?
• RQ5 Can the universal cloner mechanism be effectively harnessed to improve gate performance in integrated photonic architectures?

Key findings

• The proposed CNOT gate design exceeds the universal quantum cloner fidelity limit of 5/6, achieving a fidelity of approximately 91%.
• The system operates effectively in the weak coupling regime, which enhances stability and reduces decoherence.
• The quantum dot-microcavity platform enables a compact, scalable, and near-deterministic implementation of the CNOT gate.
• Fidelity remains high under realistic conditions, indicating robustness against experimental imperfections.
• The design demonstrates a practical pathway toward high-fidelity photonic quantum logic with potential for integration.
• The results suggest that universal cloners can be leveraged not just as theoretical tools, but as performance-enhancing components in physical quantum gate architectures.