Cardano has been ranked second in quantum readiness by a Google Quantum AI paper, trailing only Algorand and surpassing Bitcoin and XRP Ledger. The ranking assessed blockchains based on public-key exposure, key rotation support, upgrade flexibility, and transaction vulnerability windows. Cardano's eUTXO model, which keeps spending keys hashed until funds are spent, was highlighted as a key advantage in limiting visibility and reducing potential attack windows. Algorand topped the list due to its execution of quantum-resistant transactions in a live environment and support for rotating keys. Cardano was noted for its structural advantages, positioning it well for future migration to post-quantum cryptography. Meanwhile, Ethereum and Solana were categorized as having the broadest attack surfaces due to consistently visible public keys. The paper emphasizes that while quantum computers capable of breaking current cryptography do not yet exist, the focus is on upgrade readiness for future threats.