Cold Atom Single-Photon Beam Splitter with Adjustable Proportion
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Solution Overview
Problem
Existing temporal beam splitters based on electromagnetically induced transparency have a narrow bandwidth and limited ability to adjust splitting proportion, particularly for single-photon level beam splitting.
Innovation Solution
A proportion adjustable single-photon beam splitter using cold atom storage with a two-dimensional magneto-optical trap, where the switching time and optical depth of the alkali metal atomic group are controlled to adjust the splitting proportion and bandwidth, utilizing an acousto-optic modulator for dynamic control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a temporal beam splitter based on electromagnetically induced transparency (EIT) is used, then single-photon level beam splitting is achieved, but the bandwidth becomes narrow (below 10 MHz)
Solution Approach 1:
The patent changes the fundamental physical mechanism from EIT to Raman scattering, and adjusts key parameters such as using alkali metal atoms (rubidium or cesium) with specific transition levels, applying magnetic fields for Zeeman splitting, and controlling atom number density to achieve both single-photon level operation and high bandwidth (100 MHz)
2Device complexity
If a spatial beam splitter is used, then the structure is simple, but it can only split strong light and not single photons
Solution Approach 1:
The patent replaces the mechanical/optical component-based spatial beam splitter with a quantum optical system using cold atoms and Raman scattering, enabling single-photon level operation while maintaining relative structural simplicity through the use of standard cold atom trapping techniques
3Speed
If the coupling beam switching time is reduced to increase bandwidth, then the bandwidth increases, but the control precision over splitting proportion becomes more difficult
Solution Approach 1:
The patent employs feedback control through the acousto-optic modulator to precisely control the coupling beam switching, allowing dynamic adjustment of the beam splitter ratio while maintaining stable operation at high bandwidths by continuously monitoring and adjusting the splitting proportion
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
Provides a simple, high-bandwidth single-photon beam splitter with adjustable splitting proportion, capable of operating up to 100 MHz, enhancing the flexibility and efficiency of single-photon signal distribution.
Implementation Method 1
unlike the EIT scheme, the present invention adopts a Raman scheme and provides a proportion adjustable single-photon beam splitter based on cold atom storage
Implementation Method 2
the switching of the coupling beam is controlled by an acousto-optic modulator
Implementation Method 3
a two-dimensional magneto-optical trap for receiving a first optical signal to be split
Data Source
AI summary
A proportion adjustable single-photon beam splitter based on cold atom storage includes a two-dimensional magneto-optical trap for receiving a first optical signal to be split; and a coupling beam. The coupling beam is incident at a certain angle with the first optical signal to the two-dimensional magneto-optical trap. The storage time of the two-dimensional magneto-optical trap 1 can be adjusted by controlling the switching time of the coupling beam, and then adjusting a proportion of a photon number of a storage part and a photon number of a leakage part of the first optical signal. A splitting proportion may also be adjusted by controlling an optical depth of the alkali metal atomic group trapped in the two-dimensional magneto-optical trap.