SUPA Department of Physics, University of Strathclyde, Glasgow G4 0NG, United Kingdom.
Phys Rev Lett. 2013 May 24;110(21):210504. doi: 10.1103/PhysRevLett.110.210504. Epub 2013 May 23.
Measurement is integral to quantum information processing and communication; it is how information encoded in the state of a system is transformed into classical signals for further use. In quantum optics, measurements are typically destructive, so that the state is not available afterwards for further steps. Here we show how to measure the presence or absence of the vacuum in a quantum optical field without destroying the state, implementing the ideal projections onto the respective subspaces. This not only enables sequential measurements, useful for quantum communication, but it can also be adapted to create novel states of light via bare raising and lowering operators.
测量是量子信息处理和通信的基本组成部分；它是将系统状态中编码的信息转换为经典信号以供进一步使用的方式。在量子光学中，测量通常是破坏性的，因此状态在之后无法用于进一步的步骤。在这里，我们展示了如何在不破坏状态的情况下测量量子光学场中真空的存在或不存在，实现对相应子空间的理想投影。这不仅使顺序测量成为可能，这对于量子通信很有用，而且还可以通过裸提升和降低算子来适应创建新的光状态。
