Going from classical to quantum as a software developer

It is quite easy to diminish the gravity of a eureka moment if you don't pay attention. I know that when I had this one (arguably my biggest to date), I didn't quite realize the trajectory that it would set for the next chapter of my life. In late 2021, I logged on to my remote job in the software (or as we in this world call it, classical software) industry like it was any other day, when suddenly it occurred to me that something was missing.

I first pursued my degree in computer engineering because I love math, science, computing, and all that nerdy stuff. I found that I was only applying my computing knowledge in my daily tasks, and I no longer had any use for math and science! While I didn't know it at the time, this discovery marked the start of my foray into quantum computing. If you're reading this and you're unsure if there's a place for you in the field of quantum computing: there is. While I can't tell you exactly what that place is, my hope is that this post and my own path from classical to quantum will help you find it.

Contents

• Zero: Identifying the gap
• One: Finding my fit
• Two: Verifying my hypothesis
• Three: Putting my name out there
• Three-point-five: Asking the experts
• Four: Taking matters into my own hands
• My journey (so far)
• What can you do?

Zero: Identifying the gap

Let me clarify a detail about my background. While I learned a good amount of math (as well as a tiny bit of physics) in my computer engineering degree, most of it is completely irrelevant in quantum computing. What I've learned is: Where you come from does not determine where you end up. What brought me here was not my degree, but the certainty that "here" is where I wanted to be. The entirety of STEM is too vast and exciting for me to limit myself to technology alone, so I sought after a new place that fused all of its elements together.

I thought back to what my childhood self might have dreamt of doing when he grew older, and I decided quantum computing fit the bill perfectly. Every morning, when I walk into the Xanadu office and see all the chips and patents we've developed, I am struck by the sensation that I am at the forefront of scientific research. Ok, child-Matthew dreamt of being an astronaut too, but come on — let's be reasonable here! The nascent field of quantum computing was rapidly maturing, and I decided that I needed to be a part of it. Regardless of my background, I became determined to make my mark in the field, and I believe that I am still making progress down that path every day.

One: Finding my fit

The prerequisite to entering the quantum computing industry has already been covered, but I'll restate it one more time before getting on with my tale: resolve that this is what you want, and move on to step 1.

In my case, step 1 was creating a mental Venn diagram of what I wanted to work on compared to where I felt I would (eventually) be able to make strong contributions. How can I put together my experience in computer science with my desire to work more with math and physics? AI is all the craze these days, but it just doesn't speak to me. When I stumbled upon this new thing called quantum computing, I felt that I had found my path. Like any scientist knows, the next step was to verify my hypothesis.

Two: Verifying my hypothesis

The task of convincing myself that this was in fact what I wanted to be doing was both daunting and critical. As my next step, I dove into a range of different media with varying degrees of usefulness, although perhaps this phase of exploring the state of the art was valuable in itself at that point. I wish this could be the part where I tell you, dear reader, to read these 5 things and then you'll be right on your way. Unfortunately, I'm afraid there are no such things — we all arrive here with different backstories, and we all must find our own ways forward. That said, fear not, for I can offer some dos and don'ts to help you verify your own hypothesis.

I started by auditing an introductory online course for quantum mechanics. This was moderately helpful to get myself familiar with the quantum world, as it was new to me. If I could go back, I would only advise my past self to pay the money to actually take the course rather than just audit it. The full course also includes exercises and assessments, and working through these can be very helpful in digesting scientific or mathematical material. Regardless of how or where you get them, I'd highly recommend you try doing some. While quantum mechanics in itself is generally important, a refresher (or introduction if it's new to you) on linear algebra is by far the most important thing when getting into any technical work in quantum computing. If you want to engage in technical work in the field and you're worried that your linear algebra is rusty, I strongly urge you to start de-rusting those pipes.

There are lots of lectures, speeches, and talks available online on various topics in quantum computing. I found these to be much more helpful and engaging than any written content I came across, as I felt that speakers did a generally better job at highlighting the most important parts of the content being discussed. Articles on quantum computing in the media are certainly exciting, but they don't tend to offer too much beyond that. This is the trade-off between articles in media versus technical publications that cover advanced material. I say this not to dismiss these articles — they make for good reading! I say it to make sure you're staying excited about the content.

The amount of information one must absorb while transitioning into a new field can feel overwhelming, so you'll have to find your own balance between catching up to the state of the art and keeping up to date with the latest discoveries. In my personal opinion, this balance is important only inasmuch as the effect it has on your eagerness to learn and your productivity.

Some readers may be wondering if they should be keeping up with the latest preprints uploaded to the arXiv or elsewhere. If you haven't already done this, then I would (at great risk of controversy) suggest against it. The aforementioned articles are great for learning about what's being researched today, whereas technical publications can be very difficult to parse if you haven't been immersed in the world of quantum research. I assure you, there will be plenty of morning coffees over which you can flip through the newest articles on the arXiv. I am certain that one day, you will find yourself chatting about the latest paper that piqued your interest. I hope that you will look back and see how far you've come.

The next bit of content that I will recommend is a textbook. Quantum Computing and Quantum Information by Michael Nielsen and Isaac Chuang is the book that comes up most when talking to people in the field of quantum computing. I didn't buy a copy for a long while, and looking back, it probably would have been a good purchase to make early in my quantum studies. Although I did not learn directly from Nielsen and Chuang (I once tried casually calling the textbook "QCQI" and then, after a slight pause accompanied by a confused look, I was advised by a colleague that "it's called Nielsen and Chuang"), I did start working through the PennyLane Codebook (shameless plug). It's an interactive coder- (and even non-coder-) friendly way to learn all about quantum computing. When I finally got my copy of Nielsen and Chuang and started going through it, I realized that I had already learned many of the concepts from the Codebook.

I would not replace the textbook with the Codebook altogether, as the textbook naturally gets deeper into concepts, but if you're looking for a place to start to get comfortable with the basics as a ‘classical programmer', the Codebook would be a great choice. To name an example, if you're new to the field of quantum mechanics, you might not be familiar with bra-ket notation. The Codebook provides a condensed and interactive introduction to how the notation is used, whereas the textbook offers a refresher on linear algebra as it's usually taught with vector notation, followed by an introduction to bra-ket notation along with tables containing common use-cases and personalized details on how authors tend to write equations in the field of quantum mechanics.

Three: Putting my name out there

At this point, you should already be well on your way to being the next big thing in quantum computing! It's time to start planning a path forward.

In my case, I had a degree in computer engineering and a year or two of work experience in the field, so… not much quantum material on my resume. However, I felt (and still feel) quite certain that there is no perfect resume for any role, so I started looking for Master's or direct-entry PhD programs that interested me. I had not yet thought of what I would like to do after (or perhaps instead of? foreshadowing!) graduate studies, but it seemed like the right step to take. Through this search, I gained an even better sense of the state of quantum computing today, and I had new things to work on.

First, I realized that the field of quantum computing was still rather young, so the degrees in the field were fairly vague in what they were, other than the fact that they included research with a group on whatever topic they might be curious about at the time. I would like to note that while the field is still young, the state of quantum computing in academic institutions has advanced quite a bit since my search in late 2021. At the time, I didn't know much about any particular topic in quantum computing, so I just picked a whole bunch that sounded cool and started working on applications. I reached out to former professors and employers of mine to ask for references, and then started sending them in! Now, a few years later, there is already a whole world of options and specializations out there — even internship programs where talented developers can take their first steps in the quantum industry, like the Xanadu Residency Program.

Three-point-five: Asking the experts

A friend of mine caught wind of my newfound interest in quantum computing and, although he didn't know much about the field, tried helping me on my quest. As he is a fan of philosophy, he had recently come across a course-turned-book called Quantum Computing Since Democritus by Scott Aaronson. If you're new to quantum computing, Scott Aaronson is an established pillar of the community and is best known for his blog, Shtetl-Optimized, where he discusses the latest news in the field. As a quick aside, while we were discussing a recent claim that Grover's algorithm offers no quantum advantage at work, one of my colleagues declared: "I will wait for Scott Aaronson to blog about it." That should sum up how significant his blog has been for the community.

My friend first suggested I check out this lecture series, and then proposed I email Prof. Aaronson and see if he was free for a call. The lectures were interesting, so I gave it a shot. Every tenured professor's email inbox is hit daily by a deluge of potential students looking for an olive branch, and I knew this. The email was a gesture more than anything else, and I effectively moved on as soon as I sent it. Unbelievably, he replied, and we did in fact organize a Zoom meeting. Unfortunately, I had no idea why I was calling or what I was going to ask him (because I didn't believe that it would even happen), so we didn't end up saying much at all. In hindsight, the whole situation seems quite silly on my end, but I'm grateful he took the time to chat. His main message was that if I was serious about getting into the field, I had a lot more schooling to do.

While I appreciate the fact that I'd probably need a PhD in physics to do lots of things in this field, I learned that I could start in the field before getting any further degrees (more on that later). The main take-aways here are threefold: First, some jobs in the field (but not all) will require higher education. Second, if you like philosophy, you will be in good company in the quantum industry. Third, only bug Prof. Aaronson (or any professor, for that matter!) if you actually have something planned to say. 🙂 In all seriousness, the quantum computing community is invested in self-growth of all kinds, and you should absolutely reach out to its members for support throughout this adventure.

Four: Taking matters into my own hands

Once my applications were sent in, all that was left to do was to wait. Or was there more? While sitting and waiting, I came to the sudden realization that my school applications could easily be turned into job applications, and I was eager to be in the quantum world promptly. At that very moment, I googled any quantum computing job I might be remotely qualified for, and I went and Gretzky'd the industry. That is to say, of course, I took a bunch of shots just in case one made it past the goal line.

At that point, it was only January, so why wait until September to get started? My job at the time was great, but if any quantum company offered me a position, I could potentially be working in quantum computing within the month! This is when Xanadu gave me my golden ticket.

*Gretzky (verb)*: To take many shots, in the hopes that one might make it past the goal line.

I accidentally applied for a job that requires a PhD in experimental physics, and the recruiter emailed me saying that, although I did not qualify for the role, they were interested in interviewing me for a spot on the Cloud Team. It was quite sudden, and I realized that I could keep doing cloud computing while also becoming part of the quantum industry. I recognized that this was a huge opportunity, so I took it. Even though I wasn't doing anything directly quantum-related, I was suddenly immersed in the world of quantum computing. Being connected with so many people in the industry and being a part of the conversation has been such a great asset for my journey in the field, and I was suddenly both of those things! My accidental-application was super-serendipitous because I happened to send it in right when Xanadu was hiring for a role quite like the one I had at the time. Don't be discouraged if companies aren't hiring for your set of skills right at this moment - your stroke of luck will come.

Looking from the inside out, I had started to learn that there are so many other ways to take part in the quantum conversation that I never knew existed. There are countless quantum computing hackathons yearly (the best of which being QHack, of course) and Discord servers (like the one run by the Unitary Fund) devoted to quantum computing, online blogs with active community forums, and lots more. I distinctly remember being unsure about accepting this job in cloud computing at Xanadu because it was not exactly quantum computing. I have since shifted my mindset on this in two ways.

Firstly, I had zero background in quantum computing so it made perfect sense that I would start my quantum work on something less particular than quantum algorithms research or quantum chemistry (as an example). This was not my final step in my quantum career, it was my first! Secondly, working on cloud computing at Xanadu is working on quantum computing. Okay, so I'm not turning knobs and dials on some newfangled photonic device. Nor is the vast majority of the industry. There is no quantum computing if people can't access quantum computers, and that concept stretches far beyond any one topic or role; there is more than one way to be part of the quantum computing community.

Two months after starting at Xanadu, I received offers to attend several of the Master's programs that I had applied to. It was a surreal experience to receive news that is exciting, flattering and heartbreaking all at once. I obviously had a tough decision lying in front of me, so I consulted my family, friends, and some (perhaps slightly biased) colleagues to help make the call. I ultimately rejected these offers and chose to stay at Xanadu, with a plan of getting more involved in quantum software. I felt that a Masters degree could lead down one of two paths: higher education and academia, or industry work. They both seemed appealing, but I realized that the appeal of academia was advanced research, and that meant that regardless of the path I might have chosen, I was already where I needed to be to reach the next step. This was the strongest factor in my decision to reject the academic path. I'm pleased to report that I have since become a significant contributor to PennyLane, Xanadu's open-source quantum computing Python library. I'm quite certain that only my imagination can limit what I will do here next.

My journey (so far)

To help you see where your own path into quantum development could take you, this is what my own journey looked like and how I went from thinking about quantum computing in September 2021 to making it my career less than a year later.

• 2021
  • September:
    • Realize that I want more from my career
    • Start fusing my skills and interests to find a potential career path
  • October:
    • Discover quantum computing, start researching and learning
    • Begin to reach out to references for school, as well as potential supervisors
  • November:
    • Continue research
    • Start grad school applications
    • Call Scott Aaronson
  • December:
    • Submit grad school applications
    • Sit with anticipation
• 2022
  • January:
    • Apply to companies
  • February:
    • Receive offer at Xanadu, start on their cloud team ASAP
  • April-May:
    • Receive grad school offers, decide to reject them
  • August:
    • Transition to the PennyLane Core team

What can you do?

I don't mean to exaggerate when I say this: you can do absolutely anything that you can dream of in this field. I've met people from more corners of our universe than I would ever have imagined: experimental physicists that build the actual computers, patent lawyers that define intellectual property, graphic designers that translate niche information into something comprehensible, writers that tell our stories, software developers that create quantum programming tools, audio/visual artists that create quantum-inspired sensory landscapes, and the list goes on.

From quantum hackathons to open-source software contributions, to research papers and academic qualifications, there are so many ways for you to take your first steps into quantum software and learn quantum programing. In the time since I've joined the PennyLane Team, we have been adding even more content to the PennyLane Codebook (formerly the Xanadu Quantum Codebook), creating amazing Demos and preparing Datasets that can help you jump-start a quantum coding project, and we've created PennyLane Challenges where you can practice your quantum coding skills (and earn certificates to show off on your PennyLane Profile)!

Quantum computing is such a nascent field that we don't actually know all of the space that it's going to take, and that's why we need people of all backgrounds to get involved. I myself was not sure how my background in cloud computing would lend itself to the field, but that sentiment has come to feel archaic to me. If you are reading this and wondering how you can get involved, I implore you to take a shot and find out for yourself.