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Building a rubidium magneto-optical trap is not the kind of project most students encounter in an undergraduate lab. It requires optics, electronics, software, control systems, and precision measurement techniques to work together within a single experimental platform.<\/p>\n
That is exactly the challenge taken on by members of POSM, a student-led photonics and quantum-optics research group at the University of Minnesota. POSM gives undergraduate students the opportunity to contribute to serious experimental work, make real technical decisions, and help develop systems that extend well beyond traditional coursework.<\/p>\n
One of the group\u2019s most ambitious efforts is building infrastructure for a rubidium magneto-optical trap, or MOT. The project brings together laser spectroscopy, RF and analog electronics, optomechanics, feedback control, vacuum systems, imaging, and scientific software. Rather than assembling a packaged teaching experiment, students are developing the underlying systems themselves and carrying their work through fabrication, testing, revision, and integration.<\/p>\n
Building a Rubidium MOT from the Ground Up<\/h2>\n
One of POSM\u2019s first major milestones is developing a stable 780 nm rubidium spectroscopy and laser-locking system. Reaching that milestone requires students to do more than generate and control laser light. They must also measure optical signals after the beam passes through fibers, polarization optics, vapor cells, beam splitters, and other components.<\/p>\n
Those measurements introduce a problem familiar to researchers across many fields: the signal of interest is not always easy to see.<\/p>\n
As an optical signal becomes weaker, its photodetector response can disappear within amplifier noise, ambient-light fluctuations, electrical interference, and other unwanted signals. Looking at a conventional oscilloscope trace may no longer provide a clear answer, even when the optical response is still present.<\/p>\n
The challenge is not simply producing the signal. It is finding a reliable way to separate that signal from everything surrounding it.<\/p>\n
Making Advanced Tools More Accessible<\/h2>\n
Ambitious student projects often face a practical obstacle: access to equipment. Building photonics and quantum-optics infrastructure requires instruments that can generate, measure, and analyze signals throughout the development process.<\/p>\n
To support POSM\u2019s work, Digilent donated Analog Discovery 3 Pro Bundles<\/a> and Digital Discovery<\/a> units. The donation gave students access to portable test and measurement tools that could support electronics development while also fitting into the group\u2019s broader optical experiments.<\/p>\n Supporting projects like POSM reflects Digilent\u2019s commitment to making hands-on engineering education more accessible. Providing equipment does more than help a team reach its next technical milestone. It gives students the opportunity to work with real instruments, confront real measurement problems, and develop skills that are difficult to build through lectures alone.<\/p>\n For this particular experiment, Analog Discovery 3 became central to addressing POSM\u2019s weak-signal measurement challenge.<\/p>\n Rather than attempting to eliminate every source of noise, POSM students used a technique known as lock-in detection.<\/p>\n The concept begins by deliberately modulating the optical signal at a known frequency. Instead of searching for that signal across all the noise present in the measurement, students can focus on the photodetector response that remains tied to the known reference frequency and phase.<\/p>\n Using Analog Discovery 3<\/a> and WaveForms<\/a>, students could generate the modulation reference and measure the resulting photodetector response with the same portable instrument. Waveform generation, oscilloscope measurements, FFT analysis, and lock-in amplifier capabilities all contributed to the workflow.<\/p>\n The signal itself did not become stronger. The measurement became more selective.<\/p>\n That distinction helped turn an optical response that was difficult to identify on an ordinary oscilloscope trace into a measurement the team could recover, quantify, and use.<\/p>\n The value of the experiment extends beyond obtaining one successful result. Students can change the optical attenuation, modulation frequency, detector gain, averaging time, and surrounding noise conditions, then observe how each decision affects the recovered signal.<\/p>\n Concepts such as signal-to-noise ratio, measurement bandwidth, sensitivity, and noise rejection become easier to understand when students can see the tradeoffs directly. Increasing the averaging time, for example, can reduce variation in the recovered signal, but it also slows the measurement\u2019s response to genuine changes.<\/p>\n The project also connects subjects that are often taught separately. Optics, analog electronics, digital signal processing, software, and measurement theory all become part of the same experimental workflow. Students are not simply learning how an individual instrument works. They are learning how complete systems are designed, evaluated, and improved.<\/p>\n Jack Jones, POSM\u2019s electronics lead, described the difference the measurement approach made:<\/p>\n \u201cThe really nice part is that the light doesn\u2019t have to be obvious on the oscilloscope anymore. Once we deliberately modulate the beam, we already know where in frequency and phase to look for it. The Analog Discovery lets us recover that response from the detector noise and turn something we could barely see before into a legitimate, actionable optical measurement. There was no learning curve at all!\u201d<\/p><\/blockquote>\n The experience captures a lesson that extends well beyond photonics. Engineering rarely happens under ideal conditions. More often, engineers and researchers must find practical ways to extract useful information from imperfect environments.<\/p>\n Learning to recover weak signals, interpret noisy data, and design more effective measurements gives students experience that can carry into many different technical fields.<\/p>\n POSM was created to give undergraduate students meaningful access to experimental research and responsibility for helping design it. Its members are not simply observing advanced systems or following predetermined lab instructions. They are contributing to the photonic, electronic, mechanical, and software infrastructure those systems require.<\/p>\n Digilent\u2019s donated equipment supports that work by giving students flexible tools they can use across electronics development and photonics experiments. Analog Discovery 3 provides the mixed-signal capabilities used in POSM\u2019s lock-in detection work, while Digital Discovery offers complementary support for digital timing, triggering, and logic analysis.<\/p>\n Projects like POSM\u2019s rubidium MOT initiative show what can happen when motivated students have access to the right equipment, mentorship, and opportunities. The completed experimental platform will be an important technical achievement, but the experience students gain while building it may be just as valuable.<\/p>\n Digilent believes that hands-on learning plays a critical role in engineering education. By providing accessible test and measurement tools, educational resources, and support for student-led projects like POSM, Digilent helps students gain practical experience solving real-world engineering challenges.<\/p>\n Interested in bringing professional-grade test and measurement tools into your classroom, lab, or student organization? Explore Digilent’s education resources<\/a> and academic solutions<\/a>.<\/strong><\/p>\n<\/div>\n<\/div>\nFinding the Signal in the Noise<\/h2>\n
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<\/p>\nLearning Beyond the Textbook<\/h2>\n
From a Noisy Trace to an Optical Measurement<\/h2>\n
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<\/p>\nSupporting the Work Behind the Breakthroughs<\/h2>\n
Supporting the Next Generation of Engineers<\/h2>\n
