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We report a scheme for programming microresonator-based spectral pulse shapers and demonstrate it with a six-channel, sub-GHz linewidth, silicon photonic spectral shaper to generate arbitrary waveforms from optical lines of a 3 GHz electro-optic comb. 

We report on the manipulation of the time-resolved biphoton correlation function using a sub-GHz resolution silicon nitride microresonator-based spectral shaper capa-ble of programmable amplitude and phase modulation. 

We report a demonstration of a 3-channel wavelength-selective switch with individual channel bandwidths of 2 GHz and drop port loss below 1 dB, paving the way for efficient spectrum utilization in quantum networking applications. 

Precise knowledge of position and timing information is critical to support elementary protocols such as entanglement swapping on quantum networks. While approaches have been devised to use quantum light for such metrology, they largely rely on time-of-flight (ToF) measurements with single-photon detectors and, therefore, are limited to picosecond-scale resolution owing to detector jitter. In this work, we demonstrate an approach to distributed sensing that leverages phase modulation to map changes in the spectral phase to coincidence probability, thereby overcoming the limits imposed by single-photon detection. By extracting information about the joint biphoton phase, we measure a generalized delay—the difference in signal–idler arrival, relative to local radio frequency (RF) phase modulation. For nonlocal ranging measurements, we achieve ( $2\mathrm{\sigma <\#comment/>}$) precision of $\pm <\#comment/>0.04\mathrm{p}\mathrm{s}$and for measurements of the relative RF phase, ( $2\mathrm{\sigma <\#comment/>}$) precision of $\pm <\#comment/>{0.7}^{\circ <\#comment/>}$. We complement this fine timing information with ToF data from single-photon time-tagging to demonstrate absolute measurement of time delay. By relying on off-the-shelf telecommunications equipment and standard quantum resources, this approach has the potential to reduce overhead in practical quantum networks. 

Control over the duration of a quantum walk is critical to unlocking its full potential for quantum search and the simulation of many-body physics. Here we report quantum walks of biphoton frequency combs where the duration of the walk, or circuit depth, is tunable over a continuous range without any change to the physical footprint of the system—a feature absent from previous photonic implementations. In our platform, entangled photon pairs hop between discrete frequency modes with the coupling between these modes mediated by electro-optic modulation of the waveguide refractive index. Through control of the phase across different modes, we demonstrate a rich variety of behavior: from walks exhibiting enhanced ballistic transport or strong energy confinement, to subspaces featuring scattering centers or local traps. We also explore the role of entanglement dimensionality in the creation of energy bound states, which illustrates the potential for these walks to quantify high-dimensional entanglement.