Giant optical nonlinearity and photon production using single molecules coupled to a waveguide

我们建议建立一个光电路，类似于电子电路，但使用单分子和引导光束而不是晶体管和电力。这些电路被密集地封装在一个微芯片上，可能成为下一代功能极其强大的计算机的基础。一个关键的问题是，当一个光束交叉时，它们几乎不影响另一个光束，这限制了光学电路的计算能力。即使是特殊的非线性光学材料也不能引起足够的相互作用。十年前，理论学家发现了一种方法，可以在没有光束之间相互作用的情况下进行简单的量子计算，只要光子是相同的，因此无法区分。最近，这种方法在一个小的硅芯片上得到了验证。然而，光子之间缺乏相互作用仍然使得不可能将其扩展到复杂的计算，因此在实践中仍然需要一种新的强非线性材料。在这个提议中，我们展示了如何通过将光子压缩到芯片上非常微小的波导中并将单个有机染料分子放置在这些波导中来解决这个问题。在低于2K的温度下，每个分子与光的相互作用足够大，使得一个光子的通过对第二个光子的存在非常敏感。因此，该分子引起光-光相互作用，这将解决在光学芯片上扩展量子计算的核心实际问题。同样的方法在扩大规模方面取得了第二个重要的实际进展。目前，相同光子的来源-计算的原材料-是芯片外部的非线性晶体，它随机产生成对的光子。探测到其中一个光子是为了预示另一个光子的到来，该光子被发送到芯片。这种方法很难在芯片上同时获得几个光子。在这个建议中，我们展示了如何连接到波导的分子可以作为相同的单光子的板载源，可以根据需要分配。在同一芯片上可以有许多这样的集成源，同时产生许多光子，用于更复杂的计算。我们的项目是优化波导的设计和分子的放置，以实现最佳的光-光耦合和最佳的片上光子源。我们将使用这些知识来制作适合复杂应用的电路。

We propose to build a light circuit , similar to an electronic circuit, but operated with single molecules and guided light beams instead of transistors and electricity. Densely packaged on a microchip, these circuits could be the basis of a future generation of extremely powerful computers. A key problem is that one light beam barely affects another when they cross and this limits the capability of optical circuits to compute. Even special nonlinear optical materials cannot induce enough of an interaction. Ten years ago, theorists discovered a way to perform simple quantum computations without interactions between the beams provided the photons are identical and therefore indistinguishable. Recently this method was demonstrated on a small silicon chip. However, the lack of interactions between photons still makes it impossible to scale this up to complex calculations and therefore a new, strongly nonlinear material is still required in practice. In this proposal we show how the problem may be solved by squeezing the photons into very tiny waveguides on the chip and placing single organic dye molecules within these waveguides. At a temperature below 2K, each molecule has a large enough interaction with the light to make the passage of one photon very sensitive to the presence of a second photon. Thus the molecule causes a light-light interaction that will solve the central practical problem for expanding quantum computation on an optical chip. This same approach offers a second important practical advance towards scaling up. At present, the source of identical photons - the raw material of the computation - is a nonlinear crystal external to the chip, which produces pairs of photons at random. One of the pair is detected in order to herald the arrival of the other photon, which is sent to the chip. It is difficult with this approach to obtain several photons at once on the chip. In this proposal we show how a molecule attached to a waveguide can serve as an on-board source of identical single photons, which can be dispensed as needed. There can be many such integrated sources on the same chip, producing many photons simultaneously for more complex calculations. Our project is to optimise the design of the waveguide and the placement of the molecules in order to achieve the best light-light coupling and the best on-chip photon sources. We will use this knowledge to make circuits that are suitable building blocks for complex applications.