Discrete-modulated continuous-variable quantum key distribution with uncertainty principle

• URL: http://arxiv.org/abs/2607.20840v1
• Date: Thu, 23 Jul 2026 02:02:53 GMT
• Title: Discrete-modulated continuous-variable quantum key distribution with uncertainty principle
• Abstract summary: Continuous-variable quantum key distribution is a compelling framework for scalable quantum networks.<n>Current security proofs for discrete modulation rely on semidefinite programming.<n>We develop a security framework that obviates semidefinite programming in favor of an approach grounded fundamentally in the Heisenberg uncertainty principle.
• Score: 5.285976913043107
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Continuous-variable quantum key distribution is a compelling framework for scalable quantum networks due to its seamless integration with existing optical communication infrastructure. However, a fundamental gap persists between theoretical protocols requiring ideal Gaussian modulation and the constrained, discrete-modulated signals dictated by practical high-speed hardware. Current security proofs for discrete modulation rely on semidefinite programming, which suffers from prohibitive computational overhead for high-order constellations and lacks direct physical insight into non-Gaussian modulation.In this Letter, we overcome this limitation by developing a security framework that obviates semidefinite programming in favor of an approach grounded fundamentally in the Heisenberg uncertainty principle. By introducing a multi-mode entanglement-source model to characterize non-Gaussian state preparation, we establish an explicit mapping between constellation geometry and the secret key rate. This framework effectively quantifies the security implications of hardware-limited, finite state preparation, enabling both numerical and analytical security analysis under high-order constellations. We experimentally validate our method on both discrete-component and integrated photonic platforms, demonstrating that a quadrature amplitude modulation format with 256 constellation points can asymptotically approach the Gaussian capacity limit. Beyond quantum key distribution, the principle of tightening uncertainty-constrained bounds via source-mode expansion offers a paradigm for exploring the information-theoretic properties of complex non-Gaussian systems.

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