One hears a lot about quantum encryption with regards to securing electronic communications: rather less when it comes to the protection of quantum computers themselves. Were quantum computers ever to take over today's domestic digital PCs, and assuming they still needed passwords (?) will they be of the conventional kind, albeit with added security? Or would these passwords also be quantum based?

What would it mean to have a quantum password?

Quantum computer operation is fundamentally different from a standard PC. They are not going to “take over” doing spreadsheets, writing documents and playing games.

8 hours ago, swansont said:

What would it mean to have a quantum password?

It would be a superposition of ordinary passwords, of course :)

On 5/31/2025 at 9:10 PM, swansont said:

Quantum computer operation is fundamentally different from a standard PC. They are not going to “take over” doing spreadsheets, writing documents and playing games.

Why not? Or does this mean that QM computing for domestic use will not (even never?) be applicable, as far as one is able to forecast at present? I remain deeply puzzled, but thanks for responding to my initial query.

As far as I’m aware, there are no quantum computers in existence, due to the problems of preventing decoherence.

More IT hype from the tech bros, or is that too cynical of me?😉

40 minutes ago, exchemist said:

As far as I’m aware, there are no quantum computers in existence, due to the problems of preventing decoherence.

More IT hype from the tech bros, or is that too cynical of me?😉

Look at how much funding fusion gets, can you blame them...

On 5/31/2025 at 4:43 PM, GeeKay said:

One hears a lot about quantum encryption with regards to securing electronic communications:

What for? It's just that kind of hype to confuse laymen who don't understand anything. Western governments have already put in place regulations allowing themselves to circumvent passwords on any social network at any time, without knowing the password or even permission from the owners of those social networks. On each of them they force people to use 2FA. With 2FA with phone as 2nd device, you don't need to know any password (and hack encrypted transmission) to login into somebody system..

Edited June 3Jun 3 by Sensei

4 hours ago, GeeKay said:

Why not? Or does this mean that QM computing for domestic use will not (even never?) be applicable, as far as one is able to forecast at present? I remain deeply puzzled, but thanks for responding to my initial query.

The operation is different - qubits instead of bits. There are some things they would better at, a prominent example being factoring numbers, because those operations can be done in parallel.

But the record for number of qubits demonstrated was just over 1000 fairly recently. And as exchemist pointed out, decoherence is a problem. Entangling a large number of particles isn’t easy, and keeping them entangled is also not easy.

4 hours ago, exchemist said:

As far as I’m aware, there are no quantum computers in existence,

I attended a talk by Bill Phillips (Nobel in 1997) a few years back where he expressed a similar opinion. In particular, he pointed to a company that liked to litigate when people questioned their product, and flat-out stated it’s not an actual quantum computer.