Integrated Photonic Waveguide Filtering for Quantum Memory Crosstalk
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Solution Overview
Problem
Integrated photonic devices suffer from stray light scatter that leads to crosstalk between waveguides, which negatively affects quantum memories by causing decoherence and other detrimental effects.
Innovation Solution
A double escalator configuration and wavelength-dependent filter design is implemented in integrated photonic devices, utilizing SiN waveguides, to reduce scatter propagation and act as a filter, ensuring high extinction ratios by attenuating undesired wavelengths while allowing desired wavelengths to propagate with minimal loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If waveguides are placed close together to address quantum memories, then the system can control multiple qubits, but crosstalk between waveguides increases causing decoherence
Solution Approach 1:
The patent divides the waveguide structure into multiple discrete waveguides that are spatially separated and individually addressable. Each waveguide is isolated from others through careful design of the photonic crystal lattice, allowing independent control of multiple quantum memories without crosstalk-induced decoherence
Solution Approach 2:
The patent implements local modifications to the photonic crystal lattice around each waveguide, creating position-dependent optical properties. This allows light to be confined and directed locally to specific waveguides while maintaining overall system integration, thereby preventing crosstalk between adjacent waveguides
2Reliability
If scattering features are added to reduce stray light, then crosstalk is reduced, but device complexity increases
Solution Approach 1:
The patent combines the waveguide structure with scattering features into a single integrated photonic crystal device. The scattering elements are embedded within the photonic crystal lattice itself rather than being added as separate components, achieving high extinction ratios while maintaining structural simplicity and manufacturability
Solution Approach 2:
The photonic crystal lattice serves multiple functions simultaneously: it provides the waveguide structure for light propagation, creates scattering features for stray light reduction, and enables wavelength-dependent filtering. This multi-functionality achieves high extinction ratios without proportionally increasing device complexity
3Reliability
If wavelength-dependent filtering is implemented, then undesired wavelengths are attenuated, but manufacturing precision requirements increase
Solution Approach 1:
The patent achieves wavelength-dependent filtering by modifying the geometric parameters of the photonic crystal lattice, such as hole size, spacing, and arrangement. These parameter changes create bandgaps that selectively attenuate undesired wavelengths while transmitting desired wavelengths, with tolerances compatible with standard semiconductor manufacturing processes
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces crosstalk between waveguides, achieving a high extinction ratio of 100% and minimizing stray light interference in quantum memory systems, thereby enhancing the accuracy and reliability of quantum memory operations.
Implementation Method 1
The high intensity 775 nm pump photons will be attenuated in the Si waveguide due to the smaller band gap of silicon, while the down converted 1550 nm photons will propagate with minimal loss
Implementation Method 2
a plurality of scatter reduction features, comprising fill, disposed on either side of the waveguide to absorb and block photon propagation
Implementation Method 3
a first plurality of trenches etched in the substrate and disposed on either side of the waveguide so as to create an air gap along the sides of the waveguide that prevents scatter-induced sideways slab mode propagation of light
Implementation Method 4
bridges etched in the substrate and undercut beneath the waveguide so as to create an air gap beneath the waveguide so as to prevent scatter-induced underside slab mode propagation of light
Data Source
AI summary
Apparatus and method for minimum crosstalk between waveguides via on chip filtering and scatter mitigation necessary to provide tunable addressing of atomic memories. Methods are disclosed to improve the extinction ratio between coherent optical outputs capable of selectively striking a single atom in an array of atoms confined in a trapped memory.