Electrooptic quantum coherent interfaces map the amplitude and phase of a quantum signal directly to the phase or intensity of a probe beam. At terahertz frequencies, a fundamental challenge is not only to sense such weak signals (due to a weak coupling with a probe in the nearinfrared) but also to resolve them in the time domain. Cavity confinement of both light fields can increase the interaction and achieve strong coupling. Using this approach, current realizations are limited to low microwave frequencies. Alternatively, in bulk crystals, electrooptic sampling was shown to reach quantumlevel sensitivity of terahertz waves. Yet, the coupling strength was extremely weak. Here, we propose an onchip architecture that concomitantly provides subcycle temporal resolution and an extreme sensitivity to sense terahertz intracavity fields below 20 V/m. We use guided femtosecond pulses in the nearinfrared and a confinement of the terahertz wave to a volume of
Ultrashort pulses propagating in nonlinear nanophotonic waveguides can simultaneously leverage both temporal and spatial field confinement, promising a route towards singlephoton nonlinearities in an allphotonic platform. In this multimode quantum regime, however, faithful numerical simulations of pulse dynamics naïvely require a representation of the state in an exponentially large Hilbert space. Here, we employ a timedomain, matrix product state (MPS) representation to enable efficient simulations by exploiting the entanglement structure of the system. To extract physical insight from these simulations, we develop an algorithm to unravel the MPS quantum state into constituent temporal supermodes, enabling, e.g., access to the phasespace portraits of arbitrary pulse waveforms. As a demonstration, we perform exact numerical simulations of a Kerr soliton in the quantum regime. We observe the development of nonclassical Wignerfunction negativity in the solitonic mode as well as quantum corrections to the semiclassical dynamics of the pulse. A similar analysis of
 Publication Date:
 NSFPAR ID:
 10305504
 Journal Name:
 Optica
 Volume:
 8
 Issue:
 10
 Page Range or eLocationID:
 Article No. 1306
 ISSN:
 23342536
 Publisher:
 Optical Society of America
 Sponsoring Org:
 National Science Foundation
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