# A scalable Controlled NOT gate for linear optical computing using microring resonators

## TL;DR

This paper introduces a scalable, tunable CNOT gate for linear optical quantum computing using integrated microring resonators, offering increased flexibility and precision over traditional bulk optical methods.

## Contribution

It presents a novel design for a scalable CNOT gate based on microring resonators, expanding the operational parameter space and enabling tunable, low-loss quantum gates.

## Key findings

- Expanded parameter space for the nonlinear phase-shift gate (NLPSG).
- Set of one-dimensional manifolds for effective transmission amplitudes.
- Enhanced flexibility and tunability in device operation.

## Abstract

We propose a scalable version of a KLM CNOT gate based upon integrated waveguide microring resonators (MRR), vs the original KLM-approach using beam splitters (BS). The core element of our CNOT gate is a nonlinear phase-shift gate (NLPSG) using three MRRs, which we examine in detail. We find an expanded parameter space for the NLPSG over that of the conventional version. Whereas in all prior proposals for bulk optical realizations of the NLPSG the optimal operating point is precisely a single zero dimensional manifold within the parameter space of the device, we find conditions for effective transmission amplitudes which define a set of one dimensional manifolds in the parameters spaces of the MRRs. This allows for an unprecedented level flexibility in operation of the NLPSG that and allows for the fabrication of tunable MRR-based devices with high precision and low loss.

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Source: https://tomesphere.com/paper/1904.02268