As someone who has spent a fair bit of time figuring out how to explain quantum computing to people I've come to the conclusion that there are only two possible ways for people to understand it:
(1) mathematically
(2) as a finite list of things quantum computers can and cannot do
and most people are not going to understand it mathematically, least of all money people who have to watch and evaluate 10 powerpoint pitches in a day or whatever. Without the math you cannot possibly explain how superposition and entanglement work, and even that explanation requires your audience already understand how classical computers work. So you are often reduced to saying "Here is what we think quantum computers will be able to do. The timeline for accomplishing this is at least a decade out. Here are some other things that people have said quantum computers can do which they definitely will not be able to do." But then you're purely relying on your audience believing you based on your credentials rather than following their own reasoning from a place of understanding. Someone else can come in with different credentials and say different things, motivated by money or simple ignorance mixed with hope, and now your audience is playing the credential evaluation game rather than the quantum computing capability evaluation game. Mix in low interest rates and a few people who have learned what to say to get attention, and you get the current state of things.
There is a quiet core of real quantum computing research happening, surrounded by a moat of noise and hype that is required to interface with investors and the public. My sincere hope is that this quiet core accomplishes real advances before the music stops.
The wrong explanation I like about QC works is to describe it as 2^n many computers doing the same computations on related data, with the caveat that you can only query one at random.
Sprinkle some hand waiving around how you can "average them all together" or have them "check the answer with each other" before querying them.
I was just thinking about this analogy to parallel computation. It works well enough, and gives a better intuition than a list of things a QC can and cannot do, as long as they can understand that these aren't regular computers and so reading the result has some restrictions which is why it only provide exponential speedup on some problems.
I don't think that's quite true. The product state has exponential size so you'd also need some kind of tensor oracle that could manipulate an exponential quantity of information in linear time.
It's true that the product state is exponential in size. That's why the size of the quadratic matrix SU(N) matrix is N = 2^M, where M is the number of qubits. To my knowledge that's the only thing that is exponential there.
(1) mathematically
(2) as a finite list of things quantum computers can and cannot do
and most people are not going to understand it mathematically, least of all money people who have to watch and evaluate 10 powerpoint pitches in a day or whatever. Without the math you cannot possibly explain how superposition and entanglement work, and even that explanation requires your audience already understand how classical computers work. So you are often reduced to saying "Here is what we think quantum computers will be able to do. The timeline for accomplishing this is at least a decade out. Here are some other things that people have said quantum computers can do which they definitely will not be able to do." But then you're purely relying on your audience believing you based on your credentials rather than following their own reasoning from a place of understanding. Someone else can come in with different credentials and say different things, motivated by money or simple ignorance mixed with hope, and now your audience is playing the credential evaluation game rather than the quantum computing capability evaluation game. Mix in low interest rates and a few people who have learned what to say to get attention, and you get the current state of things.
There is a quiet core of real quantum computing research happening, surrounded by a moat of noise and hype that is required to interface with investors and the public. My sincere hope is that this quiet core accomplishes real advances before the music stops.