Integrated Optical Device for Entangled Photon Generation
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Solution Overview
Problem
Current optical sources for generating single photons, particularly those using classical optics, struggle to efficiently produce spatially entangled photons due to reliance on large-scale elements and lack of scalability, limiting their application in quantum cryptography and other quantum technologies.
Innovation Solution
An integrated optical device with identical arms and photon pair sources is used to manipulate optical path entanglement, allowing for the generation of either bunched or anti-bunched photon pairs through a Mach-Zehnder interferometer, where the arms are configured with identical photon pair sources and phase shifters to ensure indistinguishable optical modes, enabling efficient production of entangled photons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If large-scale optical elements are used to generate single photons, then photon generation capability is achieved, but device scalability and efficiency deteriorate
Solution Approach 1:
The device is divided into two identical optical arms, each containing a photon pair source. This segmentation allows independent optimization of each arm while maintaining overall system functionality, improving scalability without sacrificing photon generation efficiency
Solution Approach 2:
The patent uses identical copies of the photon pair source in both arms of the interferometer. This copying approach ensures that both arms have equal probability of generating photon pairs, enabling efficient entangled photon generation while maintaining device simplicity and scalability
2Adaptability or versatility
If non-identical optical arms are used in the interferometer, then device flexibility is improved, but optical mode indistinguishability and entanglement quality deteriorate
Solution Approach 1:
The patent intentionally introduces asymmetry through phase shifters in each arm, allowing independent phase control while maintaining identical optical path structures. This enables flexible adjustment of the quantum state without compromising the indistinguishability of optical modes from identical photon pair sources
Solution Approach 2:
The phase shifters allow dynamic adjustment of the relative phase between the two arms by changing the optical path length. This parameter change provides device flexibility for generating different quantum states while the identical arm structures maintain optical mode indistinguishability
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
This approach allows for the scalable and efficient generation of entangled photons, enhancing the performance of quantum cryptography and other quantum applications by ensuring identical probabilities of signal and idler pairs in each arm, thus achieving optimal entangled states.
Implementation Method 1
An example of creating two correlated photons using the χ(2) susceptibility is parametric down conversion (PDC) or spontaneous parametric down conversion (SPDC) where the probability of converting an input photon to a signal and idler photon pair is linearly proportional to the intensity of the input pump.
Implementation Method 2
An example of creating two correlated photons using the χ(3) susceptibility is spontaneous four wave mixing (SFWM) where the probability of converting an input pump photon to a correlated photon pair is quadratically proportional to the intensity of the input pump because two pump photons are required to produce the two new photons.
Implementation Method 3
an integrated optical combiner device in optical communication with a first and a second optical output path and configured to be able to interfere light from the first and second arms
Implementation Method 4
each of the first and second arms being configured to guide pump, signal and idler optical waveguide modes; wherein the pump, signal and idler optical waveguide modes guidable by the first arm are indistinguishable from the respective pump, signal and idler optical waveguide modes guidable by the second arm
Data Source
AI summary
An integrated optical device and method for generating photons by manipulating path entanglement is provided. An integrated optical splitter splits pump light between two interferometer arms wherein each arm comprises a substantially identical photon pair source configured to be able to convert at least one pump light photon into a signal and idler photon pair. An integrated optical combiner device in optical communication with a first and a second optical output path interferes light from the first and second arms and outputs the signal and idler photons by bunching the signal and idler photons together in one of the optical output paths, or anti-bunching the signal photon in one output path and the corresponding idler photon in the other optical output path.