Update July 11, 2022
Quantum advantage? – the long road ahead to making a useful quantum computer.
• Wired > “Quantum Advantage Showdowns Have No Clear Winners” by Sophia Chen (July 11, 2022) – A series of recent experiments between quantum and classical computers shows the term’s ever-evolving meaning.
Each claim of quantum advantage has set off other researchers to develop faster classical algorithms to challenge that claim.
Original post February 19, 2022
So, how is quantum physics connected with quantum computing?
Ask people on the street “What is a quantum computer?” and you’ll likely get a variety of replies. Huh? Media buzz / hype, fiction / myths, degrees of reality / research. So, levels of understanding.
A “classic” 2021 Wired article  re Majorana fermions included a 2018 video of IBM’s Dr. Talia Gershon (Senior Manager, Quantum Research) explaining quantum computing to 5 different people: a child, teen, a college student, a grad student and a professional.
“5 levels” is a format referenced in other posts, but particularly noteworthy is Wired’s “5 levels” video series (16 episodes released 2017 – 2022).
• Wired > “Quantum Computing Expert Explains One Concept in 5 Levels of Difficulty” (Released on 06/25/2018)
Dr. Gershon uses some props: a model of a quantum computer aka “the chandelier” and spinning coins.
I don’t think you’re gonna have one in your dorm room anytime soon but you’ll have access to one. There’s three free quantum computers that are all sitting in this lab here that anyone in the world can access through the cloud.
You know now that everybody around the world can access a quantum computer through the cloud, people are doing all kinds of cool things. They’re building games. [Quantum pong?]
This is such an exciting time in the history of quantum computing. Only in the last couple years have real quantum computers become available to everyone around the world. This is the beginning of a many decade adventure where we’ll discover so many things about quantum computing and what it’ll do. We don’t even know all of the amazing things it’s gonna do. And to me that’s the most exciting part.
Quantum computing is a fascinating endeavor to engineer and develop applications which rely on quantum properties: “So superposition is one quantum property that we use, entanglement is another quantum property, and a third is interference.”
The quantum computing romance has begun – as Ray Bradbury noted in a 1971 panel discussion:
“I think it’s part of the nature of man to start with romance and build to a reality. In order to get the facts we have to be excited to go out and get them and there’s only one way to do that—through romance.”
 Wired > “Microsoft’s Big Win in Quantum Computing Was an ‘Error’ After All” (Feb 12. 2021)
Quantum computers are built from devices called qubits that encode 1s and 0s of data but can also use a quantum state called a superposition to perform math tricks not possible for the bits in a conventional computer. The main challenge to commercializing that idea is that quantum states are delicate and easily quashed by thermal or electromagnetic noise, making qubits error-prone [qubits’ flakiness].
Google, IBM, and Intel have all shown off prototype quantum processors with around 50 qubits, and companies including Goldman Sachs and Merck are testing the technology. But thousands or millions of qubits are likely required for useful work. Much of a quantum computer’s power would probably have to be dedicated to correcting its own glitches.
Microsoft has taken a different approach, claiming qubits based on Majorana particles will be more scalable, allowing it to leap ahead. But after more than a decade of work, it does not have a single qubit.