Noise-powered probabilistic concentration of phase information

作者：Usuga Mario A; Mueller Christian R; Wittmann Christoffer; Marek Petr; Filip Radim; Marquardt Christoph; Leuchs Gerd; Andersen Ulrik L^*

来源：Nature Physics, 2010, 6(10): 767-771.

DOI：10.1038/NPHYS1743

Phase-insensitive optical amplification of an unknown quantum state is known to be a fundamentally noisy operation that inevitably adds noise to the amplified state(1-5). However, this fundamental noise penalty in amplification can be circumvented by resorting to a probabilistic scheme as recently proposed and demonstrated in refs 6-8. These amplifiers are based on highly non-classical resources in a complex interferometer. Here we demonstrate a probabilistic quantum amplifier beating the fundamental quantum limit using a thermal-noise source and a photon-number-subtraction scheme(9). The experiment shows, surprisingly, that the addition of incoherent noise leads to a noiselessly amplified output state with a phase uncertainty below the uncertainty of the state before amplification. This amplifier might become a valuable quantum tool in future quantum metrological schemes and quantum communication protocols.

• 出版日期2010-10