Quantum computers may one day rapidly find solutions to problems no regular computer might ever hope to solve, but there are vanishingly few quantum programmers when compared with the number of conventional programmers in the world. Now a new beginner's guide aims to walk would-be quantum programmers through the implementation of quantum algorithms over the cloud on IBM's publicly available quantum computers.

Whereas classical computers switch transistors either on or off to symbolize data as ones or zeroes, quantum computers use quantum bits, or "qubits," which because of the peculiar nature of quantum physics can exist in a state called superposition where they are both 1 and 0 at the same time. This essentially lets each qubit perform two calculations at once. The more qubits are quantum-mechanically linked, or entangled (see our explainer), within a quantum computer, the greater its computational power can grow, in an exponential fashion.

Currently quantum computers are noisy intermediate-scale quantum (NISQ) platforms, meaning their qubits number up to a few hundred at most and are error-ridden as well. Still, quantum processors are widely expected to grow in terms of qubit count and quality, with the aim of achieving a quantum advantage that enables them to find the answers to problems no classical computers could ever solve.

Although the field of quantum programming started in the 1990s, it has to date only drawn a small community. "Programming quantum computers may seem like a great challenge, requiring years of training in quantum mechanics and related disciplines," says the guide's senior author Andrey Lokhov, a theoretical physicist at Los Alamos National Laboratory in New Mexico. "Additionally, the field is dominated by physics and algebraic notations that at times present unnecessary entry barriers for mainstream computer and mathematically trained scientists."

Now, with their new guide, Lokhov and his colleagues hope their new guide will help pave the way "for the upcoming quantum computing revolution," he says. "We believe that our guide fills a missing space in the field of quantum computation, introducing non-expert computer scientists, physicists, and engineers to quantum algorithms and their implementations on real-world quantum computers."

The new guide explains the basics of quantum computing and quantum programming, including quantum algorithms.

"Very much like how classical algorithms describe a sequence of instructions that need to be executed on a classical computer, a quantum algorithm represents a step-by-step procedure, where each of the steps needs to be performed on a quantum computer," Lokhov says. "However, the term 'quantum algorithm' is usually reserved for algorithms that contain inherently quantum operations, such as quantum superposition or quantum entanglement, which turn out to be computationally powerful."