Chen Sean, Rivera Nicholas, Sloan Jamison, Soljačić Marin
Massachusetts Institute of Technology, Department of Physics, Cambridge, Massachusetts 02139, USA.
Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, Cambridge, Massachusetts 02139, USA.
Phys Rev Lett. 2025 May 30;134(21):213601. doi: 10.1103/PhysRevLett.134.213601.
Quantum states of light, particularly at optical frequencies, are considered necessary to realize a host of important quantum technologies and applications, spanning Heisenberg-limited metrology, continuous-variable quantum computing, and quantum communications. Nevertheless, a wide variety of important quantum light states are currently challenging to deterministically generate at optical frequencies. In part, this is due to a relatively small number of schemes that prepare target quantum states given nonlinear interactions. Here, we present an especially simple concept for deterministically generating and stabilizing important quantum states of light, using only third-order optical nonlinearities and engineered dissipation. We show how, by considering either a nonlinear cavity with frequency-dependent outcoupling or a chain of nonlinear waveguides, one can induce high loss for all but some desired light intensities. Specifically, we find that the stabilized intensities can correspond to an evenly spaced pattern of stablilized photon numbers. This is shown to produce important quantum states with coherent superpositions between various photon numbers. As examples of this phenomenon, we show cavities which can stabilize squeezed states, as well as produce "photon-number-comb" states. Moreover, in these types of filter cavities, Glauber coherent states will deterministically evolve into Schrodinger cat states of a desired order. We discuss potential realizations in quantum nonlinear optics. More broadly, we expect that combining the techniques introduced here with additional "phase-sensitive" nonlinearities (such as second-order nonlinearity) should enable passive stabilization and generation of a wider variety of states than shown here.
光的量子态，特别是在光频下，被认为是实现一系列重要量子技术和应用所必需的，这些技术和应用涵盖了海森堡极限计量学、连续变量量子计算以及量子通信。然而，目前要在光频下确定性地产生各种各样重要的量子光态具有挑战性。部分原因在于，给定非线性相互作用来制备目标量子态的方案相对较少。在此，我们提出了一个特别简单的概念，即仅利用三阶光学非线性和工程耗散来确定性地产生并稳定光的重要量子态。我们展示了，通过考虑一个具有频率依赖外耦合的非线性腔或一条非线性波导链，除了某些期望的光强之外，如何能对所有其他光强引入高损耗。具体而言，我们发现稳定后的光强可以对应于稳定光子数的均匀间隔模式。这被证明能产生具有各种光子数之间相干叠加的重要量子态。作为这种现象的例子，我们展示了能够稳定压缩态以及产生“光子数梳”态的腔。此外，在这些类型的滤波腔中，格劳伯相干态将确定性地演化为所需阶数的薛定谔猫态。我们讨论了量子非线性光学中的潜在实现方式。更广泛地说，我们预计将这里介绍的技术与额外的“相位敏感”非线性（如二阶非线性）相结合，应该能够实现比这里展示的更多种态的被动稳定和产生。
