Time-to-digital converter for time-resolved multi-photon coincidence measurements

纠缠是量子与经典世界最显著的偏离的物理性质。从基本的观点来看，产生纠缠光子并将其分布到遥远位置的可能性是令人着迷的，因为它导致了基于局部现实理论的预测与基于量子力学的预测之间可验证的矛盾（这种验证被称为“贝尔不等式”的测试）。另一方面，纠缠光子是量子隐形传态、量子中继器和量子网络的核心，它们允许使用量子密钥分发（QKD）来证明加密密钥的安全分发，并最终与未来的量子计算机进行量子通信。这样的网络将确保政府部门内部和之间以及卫生和银行业、企业和个人的安全通信;允许将计算任务发送到远程量子云计算机，而任何人-甚至计算机本身-都无法学习该任务;并导致真正令人难以置信的计算性能，例如快速找到“大海捞针”例如，用于机器学习（例如，用于分析大数据），以及用于理解化学反应动力学（例如，以创建更好的药品和精炼石油产品）。我们的长期目标是建立一个加拿大范围的量子网络。 这笔赠款将允许购买一个时间数字转换器（TDC），用于对多达八个单光子探测器产生的探测信号进行高时间分辨率的符合测量。TDC是迫切需要在不久的将来的实验与多纠缠光子对线的路径走向量子网络。它的及时收购将消除目前影响Tittel集团进一步发展的一个重要瓶颈：我们目前的TDC可以处理的最大光子探测率的限制;以及我们目前的设备开始恶化并可能很快变得功能失调的问题。除了在各个职业层次培养高素质的人才，推进量子光学和量子通信领域的发展外，通过收购TDC，我们的研究将确保加拿大在过去十年对量子通信进行大量投资后，在这一重要领域保持竞争力。

Entanglement is the physical property that marks the most striking deviation of the quantum from the classical world. From a fundamental point-of-view, the possibility to create and distribute entangled photons to distant locations is fascinating because it leads to verifiable contradictions between predictions based on local realistic theories and those based on quantum mechanics (such verifications are known as tests of a “Bell-inequality”). On the other hand, entangled photons are at the heart of quantum teleportation, quantum repeaters and quantum networks, which allow the provably-secure distribution of encryption keys using quantum key distribution (QKD) and ultimately quantum communication with and between future quantum computers. Such a network will ensure secure communications within and between government departments and for the health and banking industries, businesses and individuals; allow one to send a computational task to a distant quantum cloud computer without anybody - not even the computer itself - being able to learn the task; and result in truly mind-boggling computational performance, e.g. for rapidly finding ‘a needle in a haystack’ (e.g. a specific entry in an unsorted database), for machine learning (e.g. for analyzing big data), and for understanding chemical reaction dynamics (e.g. to create better pharmaceuticals and refined petroleum products). Our long-term goal is the creation of a Canada-wide quantum network. This grant will allow purchasing a time-to-digital converter (TDC) for highly time-resolved coincidence measurements of detection signals created by up to eight single-photon detectors. The TDC is urgently required for near-future experiments with multiple entangled photon pairs that line the path towards a quantum network. Its timely acquisition will remove an important bottleneck that currently impacts further developments in the Tittel group: a limit in the maximum photon detection rate that our current TDCs can deal with; as well as the problem that our current devices start to deteriorate and may soon become dysfunctional. In addition to creating highly qualified personnel at various career levels and advancing the fields of quantum optics and quantum communication, our research, through the acquisition of this TDC, will ensure that Canada, after a lot of investment into quantum communication during the past decade, remains competitive in this important area.