Do quantum computers already break current encryption today?

[Rob98]

The honest and direct answer right now is no, no existing quantum computer is currently capable of breaking the encryption that actually protects things like your online banking or messaging apps today. Breaking widely used encryption like RSA at practical key sizes requires a genuinely fault tolerant quantum computer with a very large number of stable, error corrected logical qubits, and current machines remain well below that specific threshold.

Current quantum computers do have a meaningful number of physical qubits, but physical qubits are noisy and error prone, and it takes many physical qubits working together through error correction to create just a single reliable logical qubit that can actually be used for a real computation. That overhead requirement is exactly why headline qubit counts from companies can sound impressive while the machine is still genuinely far from being able to run an algorithm like Shor's at any meaningfully threatening scale.

What is true, and what actually drives the real current urgency around this topic, is the concept of harvest now decrypt later, where an adversary can record encrypted data traffic today with the specific intention of decrypting it retroactively once a capable enough quantum computer eventually does exist. That risk is genuinely real right now, particularly for data that needs to stay confidential for many years into the future, even though the actual decryption capability itself does not currently exist yet.

That specific harvest now risk is exactly why governments and companies are already actively migrating to post quantum cryptography well ahead of any actual capable quantum computer existing. NIST has already finalized new quantum resistant standards, and major companies have set internal migration deadlines years in advance specifically because encrypted data recorded today could genuinely still be vulnerable a decade or more from now once the hardware eventually catches up.

So the honest short version is your data is safe from actual quantum decryption today. But the migration effort happening right now is specifically about protecting information that needs to stay confidential well into a future where a capable machine could plausibly exist