This is active area of research and development. As far as I am aware, we currently have the efforts on Lean Ethereum, which is kind of a longer term effort of bringing deeper improvements to make Ethereum efficient and secure for the long term, by replacing a lot of sub-optimal components with components that are known to be much closer to optimal, like zk-snarks (Zero-Knowledge Succinct Non-Interactive Argument of Knowledge)

A significant component of lean Ethereum is to future-proof the consensus layer (CL) and data layer (DL), replacing BLS and KZG with post-quantum equivalents

The community is currently focused on hash-based constructions as the leading post-quantum option, but a healthy diversity of views is expected and welcome, as I’m already hearing about lattice-based options

A few months ago, lean client teams were sprinting towards a post-quantum devnet as discussed during beam day Cannes in 2025 EthCC

https://xcancel.com/ladislaus0x/status/1994342897152311665

Transcription of above tweets:

@ladislaus0x Ethereum consensus will eventually have to switch to post-quantum (PQ) signatures — and early R&D efforts look promising!
PQ signatures pose a challenge as they are ~30x larger than today’s signatures. Dealing with aggregated signatures is even trickier, given our goal for consensus participants to verify them on low-compute and low-bandwidth devices
Tune in to weekly developer calls to track progress and learn more

@ReamLabs Ream and @zeamETH achieved devnet1 interop! New report of @qdrvm_io also achieving interop just now!
The first Lean Consensus devnet that integrates post-quantum signature signing & verification.
Next step: scale up # of validators and performance baseline for future devnets!

The main efforts driven forward were related to writing specifications for post-quantum signature aggregation and optimizations to the corresponding networking layer, which are necessary to handle the much larger post-quantum signatures

This is the repo where you can see their findings and you can also follow the progress closely on this community maintained website too: https://leanroadmap.org/

Post-quantum signature aggregation is also being worked on leanMultisig

Besides, please correct me if I am wrong, if you ever get worried about quantum, you transfer your funds to a fresh address and not transact with the new account until more guidance arrives. If no existing signature is known from an account, it will be safe.

The narrative against Ethereum was that it had high fees and no one could use it, but now gas fees have been low and cheaper transactions can be made again