Our course on quantum cryptography will soon enter its third week of instruction (out of ten weeks planned). My parallel “in-class” course at Caltech has already gone through four weeks of lectures. How is it going so far?

There are many possible measures against which to evaluate the experience. An easy one is raw numbers. Online there are a bit over 7,200 students enrolled. But how many are “active”? The statistics tools provided by EdX report 1995 “active” students last week – under what definition of “active”? EdX also reports that 1003 students “watched a video”, and 861 “tried a problem”. What is an active student who neither watched a video nor tried a problem – they clicked on a link? In any case, the proportion seems high; from what I heard a typical experience is that about 2-5% of registered students will complete any given online course. Out of 7,000, this would bring the number of active students by the end of the course at at a couple hundred, a number I would certainly consider a marked success, given the specialized topic and technically challenging material.

At Caltech there are 20 students enrolled in CS/Phys 120. Given the size of our undergraduate population I also consider this to be a rather high number (but the hard drop deadline has not passed yet!). It’s always a pleasure to see our undergraduate’s eagerness to dive into any exciting topic of research that is brought to their attention. I don’t know the enrollment for TU Delft, but they have a large program in quantum information so the numbers are probably at least twice as high.

Numbers are numbers. How about enthusiasm? You saw the word cloud we collected in Week 0. Here is one from Week 2 (“What does “entanglement” evoke in you right now?”; spot the “love” and “love story”; unfortunately only 1% of responses for either!). Some of the students speak up when prompted for simple feedback such as this, but the vast majority remain otherwise silent, so that involvement is hard to measure. We do have a few rather active participants in the discussion forums, and it’s been a pleasure to read and try to answer their creative questions each day – dear online learners, if you read this, thanks for your extremely valuable comments and feedback, which help make the course better for everyone! It’s amazing how even as we were learning qubits some rather insightful questions, and objections, were raised. It’s clear that people are coming to the course from a huge range of backgrounds, prompting the most unexpected reactions.

A similar challenge arises in the classroom. Students range from the freshmen with no background in quantum information (obviously), nor in quantum mechanics or computer science, to more advanced seniors (who form the bulk of the class) to graduate students in Caltech’s Institute for Quantum Information and Matter (IQIM). How to capture everyone’s attention, interest, imagination? The topic of cryptography helps -there is so much to be fascinated with. I started the course by discussing the problem of quantum money, which has the advantage of easily capturing one’s imagination, and for which there is a simple quantum scheme with a clear advantage over classical (cherry on top, the scheme is based on the famous “BB84 states” that will play a major role in the class via their use for quantum key distribution). So newcomers to quantum information could learn about qubits, kets and bras, while others could fend off their impatience by imagining new schemes for public-coin quantum money.

This is not an easy line to thread however, and given the composition of the class I eventually decided to err on the side of caution. Don’t repeat it, but this is my first time even teaching a full class on quantum information, and the basic concepts, not to mention the formalism, can be quite tricky to pick up. So we’re going to take it slow, and we’ll see how far we get. My hope is that the “flipped classroom” format should help needy but motivated students keep afloat by making all the online material available before it is discussed in class. Since the online course has only been going on for a couple weeks I can’t yet report on how well this will work out; my initial impression is that it is not given that the in-class students actually do spend enough time with the online material. I am yet to find the proper way to incentivize this: quizzes? rewards? The best reward should be that they manage to follow the course😉

In the coming weeks we’ll start making our way towards quantum key distribution and its analysis. Entanglement, measuring uncertainty, privacy amplification, BB84 and Eckert, and device independence. Quite a program, and it’s certainly nice to attempt it in such pleasant company!