What is Quantum Computing?

Origins

In 1986, one of the pioneers of 20th Century physics, Richard Feynman, hinted at the potential of quantum computing as an unexplored technology. He theorized that quantum computers could be used to solve difficult computational problems much faster than a traditional computer. Based on the tenets of quantum mechanics, which is the science of small particles (electrons, photons, neutrinos, etc.), this exponential computational power is what has garnered so much attention for quantum computers among researchers and tech firms across the world.

Why quantum computing?

Quantum computers place this computational power within our reach using three central tenets:

• Qubits
• Superposition
• Entanglement

Firstly, quantum computing posits a quantum bit (or qubit for short) as the centerpiece and most basic computation unit. Qubits are conceptually very similar to the bits at the heart of almost all computers today. But unlike bits that can exist in a state of either 0 or 1 at any given time, a qubit has a larger state space. This essentially means that a qubit has more possible states to choose from beyond 0 and 1, and can therefore encode a lot more information compared to a classical bit.

Also, quantum computers can use the quantum mechanical properties of superposition and entanglement of the qubits to solve difficult problems in a unique and more efficient way.

The power of quantum mechanics

Powered by multiple qubits that have superposition and entanglement up their sleeve, quantum computers represent an exciting new model of computation. Practically, researchers have used quantum computers to solve and propose solutions to NP-hard problems (e.g. Protein Folding and the Traveling Salesman Problem) and produced quantum analogs of classical algorithms. In most cases, quantum computers and algorithms exhibit polynomial and sometimes exponential time speedup over their classical counterparts.

The quantum hype

Firms like IBM, Honeywell, Zapata, Rigetti, Amazon, Google, IonQ, and others are all adopting and investing heavily in quantum computing. Most quantum computers today are ensconced in expensive refrigerated laboratories, but these companies have connected their quantum computers to the cloud. These computers are now free for anyone to access and use. In the last few years, there has also been an active shift to recognize the power of quantum computers in industrial and commercial use cases. In short, 2021 is a fun time to be learning quantum computing.

If this seems like a lot, don’t fret. We will be covering these topics in much greater detail in subsequent sections of the course. Let us first turn our attention back to qubits and how they revolutionize the world of computation.