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An efficient simulator for quantum systems is one of the original goals for the efforts to develop a quantum computer [1]. In recent years, synthetic dimension in photonics [2] have emerged as a potentially powerful approach for simulation that is free from the constraint of geometric dimensionality. Here we demonstrate a quantum-correlated synthetic crystal, based upon a coherently-controlled broadband quantum frequency comb produced in a chip-scale dynamically modulated lithium niobate microresonator. The time-frequency entanglement inherent with the comb modes significantly extends the dimensionality of the synthetic space, creating a massive nearly 400 x 400 synthetic lattice with electrically-controlled tunability. With such a system, we are able to utilize the evolution of quantum correlations between entangled photons to perform a series of simulations, demonstrating quantum random walks, Bloch oscillations, and multi-level Rabi oscillations in the time and frequency correlation space. The device combines the simplicity of monolithic nanophotonic architecture, high dimensionality of a quantum-correlated synthetic space, and on-chip coherent control, which opens up an avenue towards chip-scale implementation of large-scale analog quantum simulation and computation [1,3,4] in the time-frequency domain., Comment: 21 pages, 14 figures (including supplementary materials)

Nonreciprocal optical systems have found many applications altering the linear transmission of light as a function of its propagation direction. Here we consider a new class of nonreciprocity which appears in photon pair correlations and not in linear transmission. We experimentally demonstrate and theoretically verify this nonreciprocity in the second-order coherence functions of photon pairs produced by spontaneous four-wave mixing in a silicon microdisk. Reversal of the pump propagation direction can result in substantial extinction of the coherence functions without altering pump transmission., Comment: 12 pages, 5 figures

Photonic sensors based upon high-quality optical microcavities have found a wide variety of applications ranging from inertial sensing, electro- and magnetometry to chemical and biological sensing. These sensors have a dynamic range limited by the linewidth of the cavity mode transducing the input. This dynamic range not only determines the range of the signal strength that can be detected, but also affects the resilience of the sensor to large deteriorating external perturbations and shocks in a practical environment. Unfortunately, there is a general trade-off between the detection sensitivity and the dynamic range, which undermines the performance of all microcavity-based sensors. Here we propose an approach to extend the dynamic range significantly beyond the cavity linewidth limit, in the nonlinear modulation regime, without degrading the detection sensitivity for weak signals. With a cavity optomechanical system, we experimentally demonstrate a dynamic range six times larger than the cavity linewidth, far beyond the conventional linear region of operation for such a sensor. The approach demonstrated here will help design microcavity-based sensors to achieve high detection sensitivity and a large dynamic range at the same time, a crucial property for their use in a practical environment., Comment: research article, 13 pages, 11 figures

Generation and control of quantum states of light on an integrated platform has become an essential tool for scalable quantum technologies. Chip scale sources such as nonlinear optical microcavities have been demonstrated to efficiently generate entangled bi-photon states. However these systems have little control over the continuous variable time-energy entanglement of the photons. We demonstrate such control by preparing bi-photon states with asymmetric temporal wavefunctions by selectively modifying the density of states of the cavity modes taking part in the interaction using Rayleigh scattering-induced strong coupling of optical modes of a resonator. These states reveal exotic coherence properties and show a path forward for continuous variable quantum state engineering on a chip., Comment: 7 pages, 6 figures (including Appendix)

Many technologies emerging from quantum information science heavily rely upon the generation and manipulation of entangled quantum states. Here, we propose and demonstrate a new class of quantum interference phenomena that arise when states are created in and coherently converted between the propagating modes of an optical microcavity. The modal coupling introduces several new creation pathways to a nonlinear optical process within the device, which quantum mechanically interfere to drive the system between states in the time domain. The coherent conversion entangles the generated biphoton states between propagation pathways, leading to cyclically evolving path-entanglement and the manifestation of coherent oscillations in second-order temporal correlations. Furthermore, the rich device physics is harnessed to tune properties of the quantum states. In particular, we show that the strength of interference between pathways can be coherently controlled, allowing for manipulation of the degree of entanglement, which can even be entirely quenched. The states can likewise be made to flip-flop between exhibiting initially correlated or uncorrelated behavior. Based upon these observations, a proposal for extending beyond a single device to create exotic multi-photon states is also discussed.