Wait a minute… Don’t Lasers Heat Things Up? A Laser Cooling Primer for the Uninitiated

Classical mechanics is the study of macroscopic objects and how they react to forces, and it works well. Really well. But when it comes to small particles, the same rules don’t apply. Quantum mechanics is the underlying theory that all particles can behave like waves, and vice versa.

We can’t see quantum effects in our day to day lives because things are too hot and heavy. Even though all particles behave likes waves, the amalgamation of the sheer number of them that it takes to make anything macroscopic cancels out any ambiguity. To see the effects of quantum theory in the lab, we have to cool lithium atoms down to just microKelvin away from absolute zero and pack them all together, where they will begin to show quantum interactions.

Unfortunately, I can’t buy ultra-cold lithium at Costco (you need a gold membership), so how do we make it ourselves? Cue the lasers. Laser cooling takes advantage of the interaction between atoms and light to slow them down. Since temperature is a measure of average kinetic energy, they are now ‘colder’.

“I hate to break it to you Max, but you’ve really lost it this time. We’re talking about lasers here. LASERS. Lasers heat things up. I saw this video of a laser blowing up a balloon.”

Ok fine. You got me. I saw that video too and it’s cool. Lasers usually heat things up. They are good at doing this because of how tightly packed the energy in a laser beam is. To put it in perspective, the average person probably puts out about 250 Watts while running. A horsepower is almost 800 Watts, and engines can put out many hundreds of horsepower. So, it may be a bit of a shock that even a 0.2 Watt laser beam is actually pretty powerful, sometimes even enough to permanently blind you. Yikes. Even with less than 1/1000th of the power that you can put out just by running, a laser can do some serious damage.

This is partially due to the fact that laser light is coherent, effectively meaning it is all the same color. However, this combination of homogeneity and power ‘density’ actually also makes it perfect to cool atoms down. But how do you do it?

The answer is very clever: using the doppler shift. Most people have experienced an ambulance siren dramatically changing pitch as soon as it passes you. This is because the motion of the car changes the spacing of the sound waves travelling towards you, and so they hit your ear more or less frequently if the car is moving towards or away from you, respectively. We interpret this increased or decreased frequency as a change in pitch. Atoms ‘see’ light in exactly the same way. Light also has wavelike properties, and the motion of the atom will change the perceived frequency of the light depending on its velocity (see picture).

Another important piece of the puzzle that we need to use is the fact that a given atom can absorb or emit light only at specific frequencies. This is another quantum phenomenon, and although it is strange, it is true. A frequency of light corresponds to a color, so think of these specific frequencies as a specific color of light. For lithium, it is 671 nm, which is a deep red.

We’ve got the ingredients. How do we get the cool? Well, throw out your Ray-Bans. Imagine sending out light that has a frequency that is a little less than the one we need for the transition. If we send this beam into a cloud of gaseous atoms, then only the atoms that are moving towards the beam will see an increase in frequency, and therefore the right color light for the transition. The other atoms will see frequencies that are too low.

Even though photons do not have any mass, they do have momentum. When the atom moving towards the photon absorbs it, it gets a kick back in the opposite direction, and it is now slower! Over many cycles, we kick more and more of the atoms until they are cool enough to confine.

Although this is only the first step of many to get temperatures that are low enough to explore quantum interactions, it is amazing that massless light can cool atoms with real mass. Under the right conditions, lasers aren’t just a way to pop balloons and remove tattoos that you thought you wouldn’t regret.

Eduardo Cardenas-Torres ’19, Statistics

“I think my main turning point for believing in myself was when I got that first piece of code to run successfully”

For Eduardo Cardenas-Torres, the sky has always been the limit. Growing up, Eduardo idolized both of his parents, people who he saw working tirelessly to provide for the family. He vowed to take full advantage of the opportunity they provided, telling himself then and there he would become the first in the family to receive a master’s degree.

Going to community college didn’t dampen his goal; after two years of making the honors list at SBCC, Eduardo transferred to UCSB as a Statistical Science major, eager to get involved with research.

His perceived inexperience didn’t set him back either. After only one quarter at UCSB– and subsequently only one quarter of upper-division statistics classes under his belt– Eduardo began to reach out to professors for research opportunities.

At first, no one took a chance on Eduardo. But he remained persistent, knowing that getting research experience would be vital to his future.

Finally, Dr. Michael Nava offered Eduardo a position as a Research Assistant in the Department of Statistics and Applied Probability. Nava’s research investigated whether Author diversity affects UC journal publications, and he needed Eduardo to help him clean up and analyze data.

That too came with its struggles for Eduardo. For his first project, he was tasked with coding an API key that would allow the team to gather the data they needed. Eduardo spent an entire week trying to code the key, but couldn’t figure it out. Doubts began to creep in… were the other professors right that he wasn’t ready to do research yet?

Then, something clicked for Eduardo. After talking to his colleagues, Eduardo reprogrammed his code, and ran it once again. This time, it worked like a charm.

“I think my main turning point for believing in myself was when I got that first piece of code to run successfully,” Eduardo said. “It was also great to see how [that code] helped my team members proceed with their section of data management.”

Since then, Eduardo has used his code to collect the names of more than 75,000 authors. From there, he creates a “homophily” index, which analyzes how similar or different the authors of a particular piece are based on their ethnicities. After running his data through linear regressions and cluster analyses, he has found that the more diverse the authors on a piece are, the more likely they are to be cited in UC system publications.

Eduardo also finds himself as the de-facto leader of the group– a far-cry from the kid who couldn’t even find a research position when he started looking.

“I started off just scheduling all of the meetings for the team,” he said. “ From there, I directed the group organically towards what the next steps were [for our research].”

Through it all, the sky remains the limit for Eduardo. He has already gone to three conferences to present his research, including the SAEOPP McNair National Research Conference in Atlanta. In his fourth year now, he is well on his way to accomplishing his goal of going to grad school.

“All the grad school’s I’ve talked with have been really impressed with my research, especially because I’ve used some techniques in my research that they typically teach,” Eduardo said.

Eduardo is quick to credit Dr. Nava in his success, who has created an open and transparent research environment in which Eduardo can both learn and flourish. While Eduardo’s time in his lab may be coming to a close, his experience will impact him for years to come.

“[My research] has made me more passionate about my education and pursuing a graduate degree,” Eduardo said. “ If anyone wonders how research is, all I can say is that it’s one of the best things you can do for yourself.”

Talking to a Professor 101

Whenever I tell someone, whether it be a friend of mine, my family, or even a faculty member, that I am researching methamphetamine addiction in mice, one of the first questions I get asked is usually, “where do they get the meth from?” This question kind of bothers me. I rarely get asked specific questions about my research, and the opportunity to share the knowledge I have gained during my internship is frustratingly uncommon. To be quite honest, I don’t even have a good answer to this question. I understand that meth is a scary and almost alien substance to many people that I interact with, so the fascination with the drug itself is not unexpected. However, having the frustrating experience of people focusing on the wrong things when I am trying to convey interesting things to them has really opened my eyes to how to ask questions about research. I have begun to realize that asking research questions that can be answered with a single sentence reveal almost nothing in terms of how much other interesting information they can share. So, I have compiled a list of tips from my own experience that can help you ask deep and thought-provoking questions, as I believe that asking good questions is a major part of being a good researcher.

Step 0: Research the Research

Oftentimes, you will know beforehand if you are going to talk to a professor about their research. I have found that their websites and published article lists are often outdated; however, gathering any information you can about their area of expertise can be a tremendous help in asking great questions and getting interested in their research.

Step 1: Be confident

Professors can be quite intimidating. They are incredibly knowledgeable, experienced, and intelligent people, and meeting a professor whose work you admire can be quite daunting. I remember my first time meeting a professor one-on-one at UCSB, I was extremely nervous. I walked into his office, sweaty and totally unprepared. The first question he asked me was, “So do you have any questions for me?” It took me about fifteen seconds to stammer out my first words, and by the time we were done with the interview I thought I had completely blown it. I ended up being offered a position as a research assistant, and it made me realize that professors are people too. Professors do not always need to hear deep, thoughtful questions about their research, and they will understand that you will make mistakes. Just focus on showing your curiosity and personality, and the knowledge and critical questions will come later.

Step 2: Make connections

As a wise man once said, “Your network is your net worth.” Don’t be afraid to ask personal questions, and always remember to send a thank you email after you talk with a professor. Actions such as these will make them remember you, and there are countless opportunities out there that you will not find on your own. Having a good network of people can open many doors and help you achieve things you could never have done on your own. Beyond research, professors are amazing mentors and advice-givers, and having someone as knowledgeable as a professor to ask questions to can literally change your life.

Step 3: Have fun!

Getting a position in a research lab is never life or death. In fact, you probably won’t even really enjoy your first research experience. However, making mistakes and learning from them is a huge part of life in general, and research is no different. Don’t be afraid to try something scary! Email that professor, ask the “dumb” questions, and most of all, have fun. Ask interesting questions you want to know the answers to, and have a good time doing it, because your energy will be contagious!

Hopefully, this short guide will help you the next time you talk to a professor, and know that your research experience will teach you an incredible amount about yourself and what you enjoy. As a final piece of advice, try to make the most of every moment, because that is what life is all about.

Am I an Imposter?

Imposter syndrome is the fear of being exposed as a fraud that overshadows your actual accomplishments.

Around March, I heard that I got accepted to the AIM Photonics program at UCSB. I was so happy since UCSB is on the top of my list for Ph.D. programs. As the semester came to an end, I had a realization that I didn’t know anything about photonics. I read up on the material that my mentor sent me, but I didn’t understand most of it. I didn’t know what I would need for my research. Would I just need to understand concepts in electromagnetism? Are the materials that I learned at Cal State Long Beach enough? About a week before the program started, I started to get nervous and doubtful about my success. What if I don’t leave a good impression and have a negative impact on my chance of getting into the Ph.D. program at UCSB? What happens if I embarrass myself?

Soon, the first day of the program came and I came to realize that I was the only person that was from a Cal State, driving me to question myself even more. Was I smart enough? Could I really do this? The first day of starting my project was even worse. I couldn’t answer most of the questions that my mentor asked me– even the ones that I knew– because I kept doubting myself. I had imposter syndrome. Even though my mentor, who is extremely kind and patient, told me it takes time to understand everything, I was so mad and frustrated at myself. I pushed myself to review and learn concepts by myself, but I felt like that wasn’t enough. After I asked a question, I felt like I should have come to the solution by myself. I felt bad for asking for so much help and bothering my mentor that I always had to take a moment to consider whether to ask him or not. This was how my first two weeks were like. I continued to stay in the lab for long hours not because I had a lot of work, but because I spent so much time second guessing myself.

On the Tuesday of the third week, we had an event where we had dinner with faculty, and Dr. Luke Theogarajan attended. He is the professor that I initially wanted to work with, so I was very excited to meet him. During the event, he said something that blew my mind. At the beginning of his job at Intel and his Ph.D. program he told us he had no idea or knowledge on the projects that he was working on. Someone asked him how he was able to become so successful in a field when he didn’t know anything. His answer was mind-blowing. He said that there is one advantage to having no knowledge in the field—you don’t know what is impossible. It was the first positive perspective that I had of myself.  I realized I have experiences that others might not have that could possibly bring new ideas to the table.

Research isn’t always analyzing data and collecting samples. It also includes bringing ideas outside of the box and applying it to the research project and making a difference. To do so, not only do you need to have the knowledge but also an open mindset. I may not be the most knowledgeable, but I am openminded to any concepts that they throw at me because I am a blank sheet. The learning curve may be steeper and harder to get over, but that just means that I learned more.  As long as you have the desire and the motivation, one day that mountain you have to climb may not seem so steep.

The Importance of Research

Our professors make occasional references to the innovative work in the research on campus, but as an undergrad, we barely get a glimpse of what truly goes on in lab. In first-year lab classes, we are introduced to basic laboratory techniques and gain an understanding on lab safety. It is amazing to see how much lab courses mirror experience as an undergraduate researcher.

For example, in my intro bio lab courses, we had multiple lab practicals that tested our pipetting techniques. Getting the technique down seemed simple enough, once you got the hang of it in lab class. It seemed pretty straightforward, and I never gave it much of a second thought. However, in lab, mastering this technique is important to every experiment. Just last week, I was pipetting volumes of 1 microliter, and a quick slip on my finger could have led to us having to redo that part of the experiment. Another example is learning how to use a centrifuge. Without properly balancing the device, the centrifuge could be damaged, or someone could get injured in lab.

For me, there were also aspects of my undergraduate research experience that were somewhat unexpected. Obviously, you can’t learn all the techniques and procedures that you will have to follow in courses, so there is a certain level of on-the-job training, if you will. To me, I felt as if I was playing a game of catch up, working my way up to understand everything my mentor and the other graduate students in our lab was talking about. One big learning gap for me was my lack of prior experience in coding/computer programming. Without any formal experience, my best bet was to take to the internet and start learning MATLAB through online tutorials. In between work on our experiments, I often search up a tutorial or troubleshooting guide, in an ambitious attempt to finish a code that I have been working on for a couple weeks now.

Although you may be the only undergrad in your lab, it helps too keep in mind that you are embarking on a journey that hundreds of students have began before you. As a Gorman scholar, this feeling of self-doubt is further lifted from your shoulders when you talk with undergrads involved in research in other departments, who face similar challenges as you. The CSEP internships are an amazing experience which I’d recommend to any undergraduate. The programs teach you the applications of research, and how you can appreciate the bigger picture of what your project plays a role in accomplishing. An important part of scientific research is that it is incredibly collaborative, as each paper seems to pass the baton onto the next scientist to help solve the larger problem. In the Dey lab, my project involves making improvements to mRNA sequencing technology, and this project can be applied to scientists studying development or localized diseases. Whether or not your undergraduate experience inspires you to pursue a career in research, it is an incredible opportunity that will heighten your appreciation for science as a whole.