Heralded noiseless amplification of a photon polarization qubit
Heralded noiseless amplification of a photon polarization qubit
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DOI：
10.1038/nphys2469
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发表时间：
2013-01-01
期刊：
影响因子：
19.6
通讯作者：
Pryde, G. J.
中科院分区：
文献类型：
--
作者：
Kocsis, S.;Xiang, G. Y.;Pryde, G. J.
光子是量子信息的最佳长距离载体，但传输通道中不可避免的吸收和散射对可行的通信距离造成了严重限制。因此，信号放大将是量子技术的一个基本特征，在量子通信、计量学以及量子理论的基础测试中都有直接应用。单模的非确定性无噪声放大（1 - 5）能够规避与放大量子信号相关的挑战，比如不可克隆定理（6）以及确定性量子态放大的最小噪声代价（7）。然而，现有的设备并不适合放大基本的光量子信息载体：在两个光模式中相干编码的量子比特。在此，我们构建了一个相干双模放大器，以展示对单个光子偏振态中编码的量子比特进行的首次预示性无噪声线性放大。通过这样做，我们将一个实际量子比特通道的传输保真度提高了多达五倍。量子比特放大器有望扩展安全量子通信（8，9）以及其他量子信息科学与技术协议的范围。
Photons are the best long-range carriers of quantum information, but the unavoidable absorption and scattering in a transmission channel places a serious limitation on viable communication distances. Signal amplification will therefore be an essential feature of quantum technologies, with direct applications to quantum communication, metrology and fundamental tests of quantum theory. Non-deterministic noiseless amplification of a single mode(1-5) can circumvent the challenges related to amplifying a quantum signal, such as the no-cloning theorem(6) and the minimum noise cost for deterministic quantum state amplification(7). However, existing devices are not suitable for amplifying the fundamental optical quantum information carrier: a qubit coherently encoded across two optical modes. Here, we construct a coherent two-mode amplifier to demonstrate the first heralded noiseless linear amplification of a qubit encoded in the polarization state of a single photon. In doing so, we increase the transmission fidelity of a realistic qubit channel by up to a factor of five. Qubit amplifiers promise to extend the range of secure quantum communication(8,9) and other quantum information science and technology protocols.