Lloyd Seth
W. M. Keck Center for Extreme Quantum Information Processing (xQIT), Department of Mechanical Engineering, MIT 3-160, Cambridge, MA 02139, USA.
Science. 2008 Sep 12;321(5895):1463-5. doi: 10.1126/science.1160627.
The use of quantum-mechanically entangled light to illuminate objects can provide substantial enhancements over unentangled light for detecting and imaging those objects in the presence of high levels of noise and loss. Each signal sent out is entangled with an ancilla, which is retained. Detection takes place via an entangling measurement on the returning signal together with the ancilla. This paper shows that for photodetection, quantum illumination with m bits of entanglement can in principle increase the effective signal-to-noise ratio by a factor of 2(m), an exponential improvement over unentangled illumination. The enhancement persists even when noise and loss are so great that no entanglement survives at the detector.
利用量子力学纠缠光来照亮物体，相较于非纠缠光，在存在高水平噪声和损耗的情况下检测和成像这些物体时，能提供显著的增强效果。发出的每个信号都与一个被保留的辅助量子比特纠缠。通过对返回信号与辅助量子比特进行纠缠测量来实现检测。本文表明，对于光探测，具有m比特纠缠的量子照明原则上可将有效信噪比提高2(m)倍，这是相对于非纠缠照明的指数级提升。即使噪声和损耗极大以至于探测器处没有纠缠幸存，这种增强效果仍然存在。
