Coming to a theater near you

qcryptoThis Fall together with long-time friend and collaborator Stephanie Wehner I will be teaching a Caltech/TUDelft/EdX course on Quantum Cryptography. As I am writing this I almost feel like saying I have taught an EdX course…indeed, I just finished recording the last video for the course! Let me tell you right away that, when you’ll eventually get to see this fool absurdly gesticulating in front of at tablet, well – it was no small effort! (Not only mine: I’ll have a chance to return to this, but a serious hat tip to the Caltech production team is already in order.) This is the first post of a few in which I plan to share my experience preparing for, and then running, the course (which is officially starting on October 10th).


More often than not the first question I get asked is – why? Why did you decide to do this?? As a teacher you’re used to torturing a couple dozen students each semester… but now, not only do you want to ramp it up and torture thousands at a time, but you also want to torture yourself???

Let’s see. I can find at least two reasons. The first is rather selfish: I’m curious. I want to give it a try. My interest in the possibilities of online education, as is the case for many of us, started around 2011, during the “big boom” that followed the success of Sebastian Thrun and Peter Norvig’s Artificial Intelligence MOOC at Stanford. It is through discussing the experience of my Ph.D. advisor, Umesh Vazirani, who taught one of the early MOOCs (and still the only one on quantum computing), that I got more seriously interested in the medium. As everything he does, Umesh took the course deep at heart, and taught it passionately, striving to pack his signature “nuggets” of insight into the rigid format of a 10-minute video meant to be accessed “massively online”. Umesh had great hopes for the medium, and his course was wildly successful. It has certainly been cited as their main source of education in quantum information by many a Caltech Ph.D. applicant!


Recognize anyone?

I have the impression that the initial explosion of interest in MOOCs that took place in 2012-1014 has subsided somewhat, and the medium may be going through a phase of soul-searching: given that it is now clear MOOCs will not cure all the world’s ills, can they at least be useful for something? The “online education” medium certainly has its own challenges. As a friend working in the psychology of learning put it somewhat bluntly, “students don’t learn anything from videos – don’t waste your time” (too late, Joseph – I had started recording already). There is some truth to this (though as long as we don’t forget the 2x button there’s still a chance the students might condescend to skimming through some fraction of the videos in a quick hunt for hints towards the pset solutions).

The point though is that broadly interpreted “online education” should have much more potential for engaging the students than simply dumping video clips on them . This is what I’m interested in exploring: the extent to which it is possible to set up a stimulating, useful interactive process for the students, with some necessary “downtime” spent reading notes and working problems on their own, and some “uptime” spent watching videos but also participating in forums, thinking through stimulating questions, checking out other student’s answers, etc.

The second reason is perhaps less self-centered. I think we picked the right topic. A two-word title, each of which bound to associate with a whole range of exciting, if nebulous, concepts in the mind of any young apprentice-scientist, what is not to like? Quantum cryptography has recently (and somewhat justifiably) been drawing a lot of attention, from the expanding range of start-ups to the NSA through Chinese rockets. But surprisingly few resources are available to whomever seeks a serious introduction to the subject. While great books on quantum computing and quantum information are popping up, none gives much attention to quantum cryptography. is no book on quantum cryptography, few if any lecture notes (I searched, and the only consistent notes I could find are from a course taught by Unruh in 2014), few surveys (see this recent one by Broadbent and Schaffner, which however remains at a very high level), and a scientific literature that is not easy to navigate.


So this is what Stephanie & myself set to do, share our enthusiasm for quantum cryptography with you, young enthusiasts! What will the course be about? If you care you should watch the promo video, sign up, and take the course!

We hope to use the ten weeks we have to take the absolute beginner in quantum qkdinformation and cryptography to the level where she has a solid conceptual and mathematical understanding of quantum cryptography. A large chunk of the course will be devoted to the description and security analysis of protocols for quantum key distribution (QKD). This includes the thorny notions associated with measuring security with respect to quantum adversaries, and the recent paradigm of device independence. Beyond QKD, we also aim to give a broad overview of other feats of quantum cryptography, including primitives in two-party cryptography such as bit commitment or coin flipping, the noisy storage model, position-based cryptography, and delegated computation. Unfortunately we will not have enough time to cover quantum attacks on classical cryptosystems or post-quantum cryptography, leaving space for a companion “quantum cryptanalysis” course – volunteers?.

A word of caution: a solid background in linear algebra will be required for the course. Or at least, a will to put in the serious effort that will be required to follow the material. Making the course accessible does not mean dumbing it down, and the less mathematically inclined might find it challenging. The upshot, though, is that whomever sticks around will find it an intellectually rewarding experience, as the course will bring you to a stage where you’re basically ready to start doing research in the area. Not to scare everyone away: the course will start slow, with a “Week 0” of background material rolling out now, and the first couple weeks devoted to an introduction to the important notions of quantum information. My a priori assessment is that any 3rd or 4th year Caltech undergrad should have no problem taking the course. We’ll see how it plays out, but you should certainly try!

I will be teaching the course “inverted classroom” style at Caltech (as will Stephanie in Delft). The students will be asked to watch the videos, and more generally go through the online content, ahead of regular class meetings. In class, depending on the level of the students and their understanding of the material we will provide additional explanations or – as I hope will be possible – go further and develop our own projects extending the online material in directions of interest to the students.

This is a new experience for me, and I already stumbled through some of the beginners’ mistakes. But it’s fun! And, I hope, worth it. I’ll keep you updated. If anyone has experience (as I’m sure some of you do), unsolicited advice is more than welcome!


About Thomas

I am a professor in the department of Computing and Mathematical Sciences (CMS) at the California Institute of Technology, where I am also a member of the Institute for Quantum Information and Matter (IQIM). My research is in quantum complexity theory and cryptography.
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