ITR: Improving the Security of Quantum Cryptography with Modified Coherent State

在制造单光子态方面取得进展。但到目前为止，这些光源的效率很低，而且与波长有关，在实际应用中受到限制。最近提出并证明了一种利用亚泊松光子统计产生光子源的新方案。该方案依靠双光子量子干涉现象来减少并最终消除来自相干态的双光子事件。在本方案中，我们建议在光通信环境中实现该方案。更具体地说，我们将从光纤脉冲激光器作为主光源开始，并使用波导非线性光学材料的组合来产生双光子状态，以抵消相干状态下的双光子事件。技术上的挑战将主要是时间模式匹配的完全破坏性双光子干涉。该源具有数据速率高、方向明确、波长无关等优点，适合量子密码学的实际应用。该源也可用于组成三光子干涉仪，用于量子力学的非定域性检验。更广泛的影响量子密码学，当在正确的条件下实现时，将为安全通信提供牢不可破的代码。鉴于当前信息技术安全问题的现状，该技术的潜在效益是巨大的。所提出的方案将显著提高量子密码学的适用性。研究生和本科生参与研究是拟议计划的一个组成部分，它将为新世纪的信息时代培养和准备下一代量子物理学家。研究结果将发表在国际期刊上，以增进科学和技术的了解。

Intellectual MeritProgress has been made in producing single photon states. But so far those sources havesmall efficiency and are wavelength dependent and are limited for practical applications.Recently a new scheme was proposed and demonstrated for producing photon sourcewith sub-Poissonian photon statistics. The scheme relies on a two-photon quantuminterference phenomenon to reduce and eventually cancel the two-photon events from acoherent state. In this program, we propose to implement the scheme in an opticalcommunication environment. More specifically, we will start with a fiber pulsed laser asthe primary source and use a combination of wave guide nonlinear optical materials toproduce a two-photon state for canceling the two-photon events in a coherent state. Thetechnical challenge will primarily be the temporal mode match for a complete destructivetwo-photon interference. Such a source has the advantages of high secure data rate,well-defined direction and wavelength independence for practical application inquantum cryptography. This source can also be used to form a three-photon interferometer fornonlocality test of quantum mechanics.Broader ImpactsQuantum cryptography, when implemented in the correct condition, will provideunbreakable codes for secure communication. The potential benefit of this technology istremendous, given the current status of security issue in information technology. Theproposed program will significantly improve the applicability of quantum cryptography.Participation of graduate students and undergraduate students in the research is anintegral part of the proposed program, which will train and prepare next generationquantum physicists for the information age in the new century. Results of the researchwill be published in international journals to enhance scientific and technologicalunderstanding.