A New Course Offers Hands-on Training in Quantum Computing
Quantum computing is all the rage, but learning about it is not for the faint-hearted. “I was interested in quantum computing, but it was such a hard subject,” said Aden Lam, a PhD student working with Sebastian Will. “A lot of existing material is geared towards someone with a computer science background.”
Will has a new course that he hopes will change that. Piloted last summer, Quantum Simulation and Computing Lab (PHYS UN3084) has officially been added to Columbia’s curriculum. The first full session started this semester, and Will hopes the class will be offered each spring term.
The course gives upper-level undergraduate students the opportunity to learn the ins and outs of quantum computing and experiment with quantum devices. “We are teaching students the basics and also letting them program quantum algorithms to actually create something on their own,” said Will.
The first half of the class focuses on the theoretical foundations of quantum computing, a subject that’s still evolving. Lectures are based on recent research papers introducing the basics of quantum mechanics, how to write quantum algorithms, and the latest hardware. There’s no textbook, and there aren’t always answers, said teaching assistant (TA) Joseph Lee, a PhD student working with Ana Asenjo-Garcia. “Often, we’re learning right alongside the students,” he said.
Problem sets help students put concepts into practice and weekly tutoring sessions are available with Lam, Lee, and past graduates of the pilot course, Shuhan Zhang and Arjun Kudinoor. The TAs help students work through theoretical questions and write their own algorithms that can be implemented on quantum devices.
"This is all about lowering the barrier to entry,” said Will. “We don't want students to be put off by the complexity of quantum computing.
A quantum algorithm involves two main components: quantum states and quantum gate operations.
- Quantum states represent information. Whereas strings of ones and zeros represent information with classical computer bits, quantum bits (qubits) use superpositions that are both one AND zero.
- Quantum gate operations are the steps that tell the qubits how to interact.
Quantum states plus quantum gate operations form a quantum circuit, which provides a measurement. Depending on the application, you will either record that measurement, feed it back into the algorithm, or perform classical computations with it, like addition or optimization.
The second half of the term is project-based. “You get to explore the topics covered in the lectures, which reflect real research, and then try to go beyond them,” said Kudinoor. “That was my favorite part of the course.”
Students pair off to work with one of two quantum computing devices: an entangled photon system called QuTools, in Pupin Hall, or one of IBM’s quantum computers via Qiskit. At the end of the term, students present their projects and write up their results, providing training in scientific publishing as well.
Will chose the systems as accessible options for students to learn about quantum hardware and software. QuTools uses entangled pairs of photons to represent quantum bits (qubits) and is a platform for experimentation, while IBM’s quantum computers, which use qubits made from superconducting materials, let the students engage with quantum algorithms.
Zhang used the entangled photons for her project on a security scheme called quantum key distribution during the pilot. “It’s real hardware, and you have to do everything manually, like calibrating the lasers and interpreting all your measurements,” she said.
Qiskit is a software package accessible through different programming languages, including Python, which lets students write algorithms to perform calculations for their projects on IBM’s quantum computers. As a student in the pilot course, Kudinoor used Qiskit to develop a multi-qubit quantum teleportation scheme, a technique for transferring information across devices.
That wasn’t exactly his original idea, however. “The option to change your mind and still be able to do well in the course was something that I found really rewarding,” he said.
Students are told to take risks with their projects, and that it’s ok to fail. “That scares a lot of them,” said Lee. “But it’s like real research: sometimes you get an exciting new result, and sometimes you prove nothing. That’s not a waste of time—you’ve just figured out something that doesn’t work.”
“We grade based on creativity and on effort—tell us what you’ve tried and if it didn’t work, hypothesize why not,” said Lam.
During the course, the students also attend an industry seminar series. This spring, Columbia hosted speakers from IBM, Bloomberg, and two quantum start-ups, QuEra and Quantinuum, who discussed the different quantum hardware they use and their goals for quantum computing. “We want to show the students the power and limitations of current approaches,” said Will. “There are a lot of open questions that academic and industry researchers are still working out.”
More than once, he recalls being asked what a quantum computer is actually good for. “We want the students to learn for themselves that quantum computing is a research field, and there is a lot to do,” he said.