Interferometer Controlling Photon Coalescence via Delay
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Solution Overview
Problem
The Hong-Ou-Mandel interferometer does not allow for control over the outputs of coalescent photons, limiting the ability to manage the probabilities of photons appearing on specific outputs.
Innovation Solution
An interferometer is designed with optical sources generating coherent pump pulses and interferometric means to generate both symmetric and antisymmetric states, allowing for a weighted sum of these states to control the output probabilities of coalescent photons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a standard HOM interferometer is used to generate coalescent photons, then photon coalescence is achieved, but control over the output probabilities of photons is lost
Solution Approach 1:
The interferometer is divided into two independent interferometric means (first and second), each capable of generating photons in specific quantum states. This segmentation allows independent control of symmetric and antisymmetric state generation, enabling precise manipulation of output photon probabilities while maintaining manageable device complexity through modular design.
Solution Approach 2:
The patent introduces dynamic control mechanisms including a delay line and polarization phase-shifter that can be adjusted in real-time. These dynamic elements allow the system to transition between different quantum states (symmetric and antisymmetric) and control the temporal and polarization characteristics of photons, providing adaptability in output probabilities without requiring a complete redesign of the interferometer structure.
2Adaptability or versatility
If delay is altered to control photon coalescence, then output probabilities are managed, but temporal precision requirements increase
Solution Approach 1:
A polarization phase-shifter is introduced as an intermediary element that mediates the control of photon states. Instead of relying solely on precise temporal delay adjustments, the phase-shifter provides an additional control dimension through polarization manipulation. This intermediary allows for coarser, more manageable delay settings while achieving fine control over output probabilities through polarization state manipulation.
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
Enables electronic control over the coalescence of photons, acting as a two-photon switch by altering the delay to manage the probabilities of photons on specific outputs, enhancing the management of photon outputs.
Implementation Method 1
due to the phenomenon of spontaneous parametric down-conversion (SPDC), the crystal 4 can generate a pair of converted photons
Implementation Method 2
The delay line 6 is able to alter the optical length of the first optical path 20 with respect to the second optical path 22
Implementation Method 3
the polarization phase-shifter 8 is formed by a birefringent crystal, which delays photons having different polarizations differently, namely by introducing controlled phase shifting
Implementation Method 4
The optical beam splitter 14 is of the so-called 50/50 type and has a first and a second input and a first and a second output
Implementation Method 5
first interferometric means configured to receive the first pump pulse and generate an antisymmetric state with two coalescent photons, and second interferometric means configured to receive the second pump pulse and to generate a symmetric state with two coalescent photons
Data Source
AI summary
An interferometer for controlling the coalescence of a pair of photons, including: an optical source, which generates a first and a second pump pulse coherent with each other and shifted in time by a delay; and a first interferometric stage, which receives the first pump pulse and generates an antisymmetric state with two coalescent photons (1/√{square root over (2)}(|21,02−|01,22)). The interferometer also includes a second interferometric stage, which receives the second pump pulse and generates a symmetric state with two coalescent photons (1/√{square root over (2)}·(|21,02+|01,22)), the first and the second interferometric stages being connected in a manner such that the interferometer outputs a final state equal to a weighted sum of the antisymmetric state and of the symmetric state (1/√{square root over (2)}·(|21,02+|01,22)+eiτ·1/√{square root over (2)}·(|21,02−|01,22)), the weights of the sum being a function of the delay.