Laser Physics Centre, Research School of Physics and Engineering, Australian National University, Canberra, Australian Capital Territory 0200, Australia.
Nature. 2010 Jun 24;465(7301):1052-6. doi: 10.1038/nature09081.
Storing and retrieving a quantum state of light on demand, without corrupting the information it carries, is an important challenge in the field of quantum information processing. Classical measurement and reconstruction strategies for storing light must necessarily destroy quantum information as a consequence of the Heisenberg uncertainty principle. There has been significant effort directed towards the development of devices-so-called quantum memories-capable of avoiding this penalty. So far, successful demonstrations of non-classical storage and on-demand recall have used atomic vapours and have been limited to low efficiencies, of less than 17 per cent, using weak quantum states with an average photon number of around one. Here we report a low-noise, highly efficient (up to 69 per cent) quantum memory for light that uses a solid-state medium. The device allows the storage and recall of light more faithfully than is possible using a classical memory, for weak coherent states at the single-photon level through to bright states of up to 500 photons. For input coherent states containing on average 30 photons or fewer, the performance exceeded the no-cloning limit. This guaranteed that more information about the inputs was retrieved from the memory than was left behind or destroyed, a feature that will provide security in communications applications.
按需存储和检索光的量子态，而不破坏其所携带的信息，是量子信息处理领域的一个重要挑战。由于海森堡不确定性原理，用于存储光的经典测量和重建策略必然会破坏量子信息。人们已经投入了大量精力来开发能够避免这种代价的设备，即所谓的量子存储器。到目前为止，使用原子蒸气并将其限制在低效率（小于 17%）范围内，成功地展示了非经典存储和按需召回，其使用的量子态平均光子数约为 1，强度较弱。在这里，我们报告了一种用于光的低噪声、高效率（高达 69%）量子存储器，它使用固态介质。该设备允许更忠实地存储和检索光，比使用经典存储器更能实现单光子级弱相干态到多达 500 个光子的亮态的存储和检索。对于输入相干态，平均包含 30 个或更少的光子，其性能超过了无克隆限制。这保证了从存储器中检索到的信息比留下或破坏的信息更多，这一特性将为通信应用提供安全性。
