Single-photon source, driven by composite pulse sequences for applications in a doped-solid quantum memory

单光子源，由复合脉冲序列驱动，适用于掺杂固体量子存储器中的应用

• 批准号: 410249930
• 负责人: Professor Dr. Thomas Halfmann
• 金额: --
• 依托单位: Arbeitsgruppe Nichtlineare Optik und Quantenoptik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/410249930?language=en
• 关键词: Single; photon; source; driven; composite

Quantum memories are a key component of any quantum information architecture. As photons have negligible interaction with each other, they are ideal carriers for quantum information. Thus, optical memories for single photons are required. The storage time and efficiency are the most relevant benchmarks for quantum memory protocols. In previous years, the applicant conducted thorough investigations on light storage by electromagnetically-induced transparency (EIT) in Pr:YSO crystals. We demonstrated EIT storage times up to the regime of one minute, and storage efficiencies of up to 76 %. However, these experiments still operated at the level of classical light. To push towards an EIT quantum memory, we require now a source for narrow-band single photons.The proposal deals with the experimental setup of a narrow-band single-photon source, based on the Duan-Lukin-Cirac-Zoller (DLCZ) quantum memory approach, implemented in an ensemble of cold Rubidium atoms from a specifically designed magneto-optical trap (MOT) to provide large optical depth.As novel and powerful variants of the DLCZ approach, we propose schemes based on composites pulses (CP) and stimulated Raman adiabatic passage (STIRAP) to drive collective atomic coherences corresponding to a robust and very precisely defined excitation by a single photon. Important advantages are (i) higher duty cycle and essentially deterministic operation of the source by adiabatically-stimulated rather than spontaneous emission, (ii) larger brightness by confining the single-photon emission volume towards the forward direction, (iii) larger robustness with regard to fluctuations of experimental parameters. As an alternative to DLCZ, we propose the implementation of an EIT-based quantum filter, which transmits only single-photon states. The approaches are of significant interest for quantum technologies also well beyond light storage. As a new technical development, we will implement the concepts also in cold Rubidium atoms loaded into a hollow-core fiber. Recently we demonstrated huge optical depths OD > 1000 in such a setup, i.e. orders of magnitude beyond typical values in previous DLCZ experiments. This enables further major improvements towards lower noise and higher brightness. Finally, we will efficiently convert the single photons at 795 nm emitted from Rubidium by sum-frequency mixing with intense mid-infrared radiation at 2.55 µm in a periodically-poled lithium-niobate (PPLN) waveguide, to obtain single photons at 606 nm, i.e. matched to a Pr:YSO memory.

量子存储器是任何量子信息架构的关键组成部分。由于光子之间的相互作用可以忽略不计，因此它们是量子信息的理想载体。因此，需要单光子的光存储器。存储时间和效率是量子存储协议最相关的基准。在过去的几年里，申请人对Pr:YSO晶体中的电致透明（EIT）光存储进行了深入的研究。我们演示了EIT存储时间长达一分钟，存储效率高达76%。然而，这些实验仍然是在经典光的水平上进行的。为了推进EIT量子存储器，我们现在需要一个窄带单光子源。该提案涉及窄带单光子源的实验设置，基于端- lukin - cirac - zoller （DLCZ）量子存储器方法，在冷铷原子集合中实现，该集合来自专门设计的磁光阱（MOT），以提供大的光深度。作为DLCZ方法的新颖和强大的变体，我们提出了基于复合脉冲（CP）和受激拉曼绝热通道（STIRAP）的方案来驱动集体原子相干，对应于单个光子的鲁棒和非常精确定义的激发。重要的优点是：(i)通过绝热激发而不是自发发射来实现更高的占空比和基本上确定的源操作，（ii）通过将单光子发射体积限制在向前方向来实现更大的亮度，（iii）对于实验参数的波动具有更大的鲁棒性。作为DLCZ的替代方案，我们提出了一个基于eit的量子滤波器的实现，它只传输单光子态。这些方法对量子技术也非常有意义，远远超出了光存储。作为一项新的技术发展，我们还将在冷铷原子加载到空心芯光纤中实现这一概念。最近，我们在这样的设置中展示了巨大的光学深度OD bbb1000，即超过以前DLCZ实验中的典型值的数量级。这使得进一步的重大改进，以更低的噪音和更高的亮度。最后，我们将在周期性极化的铌酸锂（PPLN）波导中，通过与2.55µm强中红外辐射的和频混合，有效地转换铷发出的795 nm的单光子，获得606 nm的单光子，即与Pr:YSO存储器匹配。