Our brainstorming process consisted of establishing a very basic idea at the beginning using our entry-level knowledge. However, as we interviewed experts and learned more about how products similar to ours worked, we continuously adjusted the design according to what the best known way to achieve our goals was.
We brainstormed several potential solutions, including a photoelectric radar, neutrino radar, muon radar, double slit radar, and finally the interferometric radar.
We will use normal 50/50 beam splitters as they are the most effective beam splitter for our design. As of current designs, they can be a normal size within a range of 5 mm to 2 inch cubes.
We want to use a laser using a wavelength of 1550 nm and beam waist radius of 31.4 mm.
We will need sheet mirrors that highly polished with minimal imperfections in order to ensure smooth operations of our interferometer with minimal distortion caused by dirty surfaces.
Optimal mirror size
Due to the high distance between the satellite and the bottom station and the wave-particle duality of the photons, they will spread out significantly between the output and detection. Therefore, we must find both the optimal beam waist radius in the satellite and the minimum size the mirror must be to reflect all of the photons to the detectors.
Shape
We will mount 32 individual systems in a cylindrical shape to create a display based on the radius between systems (5.625°) multiplied by the found length of the plane at that system. This design is the best design we found that can reliably detect velocity and altitude in a given area.
We have chosen to use superconducting nanowire single-photon detectors (SNSPD or SSPD) for their “very high detection efficiency, very low dark count rate and very low timing jitter.” They are able to detect single photons, which is critical for our device and are the fastest detector for single photon counting. They are very often used in quantum optical systems.
Math
Solving for the length of the plane in one direction and for the velocity.
l=(ts/tr+1)d
v=d/tr
l: Length of the plane
ts: time silent (no signal at all detected)
tr: time right (time from start of signal detection in D2 to ts
d: distance between the beams
Since we are using the system over such a large distance, from a satellite to Earth, we will need an incredibly special and powerful laser to make it the distance. The Beam Waist Radius is the central part of the laser that determines the curve of the light wave. Here, we are determining the optimal Beam Waist Radius for the system, found to be 4.15 meters.
Although light can be described as a particle (photon), it can also be described as a wave, and will follow wave properties. Therefore, as the distance increases from its emission to capture, it will spread out. The math shown below describes the optimal size of the mirror necessary to capture all of the light to reflect it to the second beam splitter, found to be an 11.74 meter diameter mirror.
For a full description of the math and process used, look in our complete Design Documentation here.
Radar can reliably detect classical-radar-evading stealth aircraft more than 50% of the time
Radar signal must not be absorbed and/or deflected by the plane
Radar should relatively disguised within the environment (so not too large, perhaps camouflaged)
Should be resistant to weathering and functionable in a variety of climates
Data from the product should be practically and speedily interpretable in order for humans to estimate the trajectory of the aircraft
Cannot be too large that it drastically sticks out of the environment and can be readily detected from the sky
Shouldn’t take longer than 10 years, or at least the project should be finished before quantum entanglement is ready to be implemented in large scale projects
Product should not emit harmful levels of radiation (more than 1000 mSv)
Customer Needs
A radar that can detect aircraft that can get past classical radars through wave deflection and/or absorption.
Performance
Product should reliably detect stealth aircraft
Target Cost
The Department of Defense has a seemingly infinite budget, but we estimate it would cost $750,000,000 for realistic R&D as well as practical implementation.
Size and Weight
There are no size and weight restrictions barring something morbidly massive.
Aesthetics
Our several aspects of the radar should be relatively blended in with the surroundings if at all possible.
Materials
Certain materials (like bromine and bismuth) that are conductive to quantum states would be preferable.
Safety, Legal, and Ethical
Product cannot cause harmful levels of radiation to the surrounding life and to the individuals operating the radar.
Ergonomics
Product should be relatively easy to use
Product Life
As product is the forefront of technology, we estimate this product will be viable for fifty years.
Reliability & Maintenance
This product will require minimal maintenance, photons will thrive in nearly all circumstances.
Since we already had a very strong concept of a radar that we had agreed to pursue, we decided to use our decision matrix to decide between different aspects of our radar: whether or not to utilize triangulation, whether or not to use squeezed states, what wavelength of light to use, and what orbit satellite to use.
Triangulation: We ultimately decided against triangulation as the main purpose of triangulation was attempting to find the altitude. However, we were able to mechanically solve this problem within one system by adding the cone system along with the cylindrical system, and using time differences between the two to determine altitude. Attempting triangulation would also have been incredibly expensive and hard to accomplish.
Squeezed States: We decided against using squeezed states to simplify the radar system and because it would not have been worth it for our project. Using squeezed states would have required a lot more specialized equipment that we would have to account for, and though it would have provided slightly more accuracy, the cost would outweigh the benefit in our case.
Wavelength: We decided on 1550 nm wavelength of light after talking to multiple experts and looking at current military LiDAR systems. As our design is modeled off of LiDAR systems, it would make sense to use a similar wavelength. Additionally, experts confirmed this wavelength would be most useful in reducing error.
Satellite Orbit: We decided to work with a Low Earth Orbit satellite constellation. Although it would require more satellites and coordination between them, the distance between Earth and a geostationary satellite was too large for the radar, and would require too powerful of a laser and too large of mirrors to be feasible.