Quantum-coherent coupling of a mechanical oscillator to an optical cavity mode
Quantum-coherent coupling of a mechanical oscillator to an optical cavity mode
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DOI：
10.1038/nature10787
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发表时间：
2012-02-02
期刊：
影响因子：
64.8
通讯作者：
Kippenberg, T. J.
中科院分区：
文献类型：
--
作者：
Verhagen, E.;Deleglise, S.;Kippenberg, T. J.
光场已被广泛用于实现对原子和离子（1，2）、分子和原子气体的运动自由度和内部自由度的量子控制。以类似方式控制宏观机械振荡器的量子态的途径是通过适当设计的光学腔中的辐射压力来利用光学和机械自由度之间的参数耦合（3-6）。如果光机械耦合是“量子相干的”-也就是说，如果相干耦合率超过光学和机械退相干率-量子态从光场转移到机械振荡器，反之亦然。这种转移允许使用广泛的可用量子光学技术来控制机械振荡器状态。然而，到目前为止，微机械振荡器的量子相干耦合仅在毫开尔文温度下使用微波场实现（7，8）。由于大的机械退相干率（9）和克服光耗散（10）的困难，光学实验还没有达到这种状态。在这里，我们实现了光子和微机械振荡器之间的量子相干耦合。同时，耦合到冷光子浴将机械振荡器冷却到1.7 +/-0.1个运动量子的平均占有率。用弱经典光脉冲激发揭示了光场与微机械振荡器之间在时域中平均小于一个量子的能量交换。这种光机系统在机械振荡器和光学光子之间建立了一个有效的量子接口，可以通过光纤提供量子态的无消相干传输。我们的研究结果提供了一条将机械振荡器用作量子换能器或用于微波-光量子链路的途径（11-15）。
Optical laser fields have been widely used to achieve quantum control over the motional and internal degrees of freedom of atoms and ions(1,2), molecules and atomic gases. A route to controlling the quantum states of macroscopic mechanical oscillators in a similar fashion is to exploit the parametric coupling between optical and mechanical degrees of freedom through radiation pressure in suitably engineered optical cavities(3-6). If the optomechanical coupling is 'quantum coherent'-that is, if the coherent coupling rate exceeds both the optical and the mechanical decoherence rate-quantum states are transferred from the optical field to the mechanical oscillator and vice versa. This transfer allows control of the mechanical oscillator state using the wide range of available quantum optical techniques. So far, however, quantum-coherent coupling of micromechanical oscillators has only been achieved using microwave fields at millikelvin temperatures(7,8). Optical experiments have not attained this regime owing to the large mechanical decoherence rates(9) and the difficulty of overcoming optical dissipation(10). Here we achieve quantum-coherent coupling between optical photons and a micromechanical oscillator. Simultaneously, coupling to the cold photon bath cools the mechanical oscillator to an average occupancy of 1.7 +/- 0.1 motional quanta. Excitation with weak classical light pulses reveals the exchange of energy between the optical light field and the micromechanical oscillator in the time domain at the level of less than one quantum on average. This optomechanical system establishes an efficient quantum interface between mechanical oscillators and optical photons, which can provide decoherence-free transport of quantum states through optical fibres. Our results offer a route towards the use of mechanical oscillators as quantum transducers or in microwave-to-optical quantum links(11-15).