A scheme for heralded generation of frequency-bin photonic qubits via spontaneous four-wave mixing in a system of coupled microring resonators (a photonic molecule) is developed so that the qubit state is fully controlled by the frequency amplitude of the pump field. It is shown that coupling parameters of the photonic molecule can be optimized to provide generation of nearly pure heralded photons. The heralded qubit state does not depend on the microring resonator mode frequency, thereby allowing one to take advantage of frequency multiplexing for improving efficiency of quantum information processing.

Generating frequency-bin qubits via spontaneous four-wave mixing in a photonic molecule

The construction of large-scale integrated photonic circuit cannot be separated from the important role played by silicon-based optoelectronic devices. As a basic and important link in on-chip photon propagation, beam splitting is of great significance for the efficient utilization of sources and the compact integration of optoelectronic devices. It is widely used in power splitting, polarization separation, wavelength division multiplexing and other scenarios. This paper reviews the on-chip beam splitting methods in recent years, which are mainly divided into the following categories: y-branch, multimode interference coupling, directional coupling, and inverse design. This paper introduces their research status, including optimization design methods, functions and applications in large-scale quantum chips and optoelectronic hybrid integration, looking forward to providing a reference for the further research of beam splitting methods and the wide application of beam splitters in the frontier field in the future.

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Methods and applications of on-chip beam splitting: A review

We present the optimal design for an on-chip single-photon source based on spontaneous four-wave mixing in a system of coupled ring microresonators, which provides frequency uncorrelated joint spectral amplitude of the biphoton field and thereby generation of pure single-photon heralded states. A simple method is proposed for suppressing negative dispersion effects by optimizing the controlled spectroscopic parameters of the system. It shown that the optimal coupling parameters, in combination with the optimal spectral width of the pump pulse, give rise to the highest purity of the heralded photons for a given pump linewidth.

Generating pure single-photon states via spontaneous four-wave mixing in a system of coupled microresonators

Spontaneous four–wave mixing (SFWM) in a microring resonator is considered theoretically. The joint spectral amplitude and Schmidt number of generated biphoton field are calculated numerically for different pump pulses. Optimal pulse shapes that provide maximum efficiency of SFWM and minimum frequency correlations between signal and idler photons are found.

/pdf/studying-frequency-correlations-of-photon-pairs-generated-t2jwl40i5o.pdf

Studying frequency correlations of photon pairs generated via spontaneous four–wave mixing in a microring resonator

A theory of spontaneous four-wave mixing in a ring microcavity is developed. The rate of emission of biphotons for pulsed and monochromatic pumping with allowance for the dispersion of group velocities is analytically calculated. In the first case, pulses in the form of an increasing exponential are considered, which are optimal for excitation of an individual resonator mode. The behaviour of the group velocity dispersion as a function of the width and height of the waveguide is studied for a specific case of a ring microcavity made of silicon nitride. The results of the numerical calculation are in good agreement with the experimental data. The ring microcavity is made of two types of waveguides: completely etched and half etched. It is found that the latter allow for better control over the parameters in the manufacturing process, making them more predictable.

https://iopscience.iop.org/article/10.1070/QEL16511/pdf

P. P. An

Papers

Optimisation of spontaneous four-wave mixing in a ring microcavity*

Study of microheater’s phase modulation for on-chip Kennedy receiver