Specifically, the enormous power of the tech could be used to crack the best cyber security we currently have in place.
A new report on the "progress and prospects" of quantum computing put together by the National Academies of Sciences, Engineering, and Medicine (NASEM) in the US says that work should start now on putting together algorithms to beat the bad guys.
The worry is that the vast processing power could be used to break the public-key encryption that we currently rely on in all kinds of ways – from protecting our private messaging app conversations to ensuring a secure connection to banking websites.
"While defeating currently deployed public-key encryption using the best available conventional computer is effectively impossible, a quantum computer could potentially perform this task in no more than a few hours," explains the press release accompanying the NASEM report.
Encryption essentially encodes data so it looks like nonsense to anyone not authorised to see it. The math problems required to beat it are virtually impossible to solve by today's computing standards, which is why it's used so widely.
However, the NASEM experts recommend that preparations for quantum-level attacks should start now – the report says that even if a super-code-cracking computer is still 30 years off, replacing existing web standards is going to take a long time.
If you think about just how many systems rely on digital communications and encryption, including phone networks and electricity grids, it's clear that any successful quantum cyber attack is going to cause some serious problems.
Even if there's not much to interest hackers in your emails, government and military secrets are at risk of being exposed, too.
"From cars to planes to power plants – if they will be operational 15 to 30 years from now, they already need to begin planning a migration towards [quantum-safe] cryptography," IBM Research quantum cryptography manager Michael Osborne, who wasn't involved in the new report, told Gizmodo.
If you're new to the idea of quantum computing, on the simplest level it replaces the bits of today's computers – those binary 1s and 0s – with specially controlled qubits, capable of existing as 1 or 0, or a superposition of both at the same time.
This superposition state provides an exponential amount more processing power. For example, complex, data-heavy systems like climate change models could benefit hugely from the extra computing power. We'll be able to see patterns and trends that currently elude us.
And the report does emphasize that the benefits of quantum computing are likely to outweigh the security risks. Progress in fields like quantum gravity and artificial intelligence could be rapidly sped up with these new machines.
While we have what are called quantum computers in the world today, they're really just early first steps. As exciting and as promising as they are, they require very particular environments to work, and only have a very limited amount of practical use.
In fact, there's still some debate as to whether we'll ever get to the stage where quantum computers can ever become genuinely useful tools, reliable and accessible enough to be helpful outside specialised laboratories.
The NASEM committee is confident.
"There has been remarkable progress in the field of quantum computing, and the committee doesn't see a fundamental reason why a large, functional quantum computer could not be built in principle," says the committee chair Mark Horowitz, from Stanford University in California.
"However, many technical challenges remain to be resolved before we reach this milestone."