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Quai Technology
Quai's architecture rests on a single insight: proof-of-work doesn't have a throughput limit — single chains do. This page explains the mechanisms that let one pool of mining work secure many coordinated chains.
The technical thesis
Proof-of-work remains the only consensus mechanism with fifteen years of adversarial evidence behind it — permissionless, energy-anchored, and free of trusted committees. What it lacked was a way to scale: a single chain serializes the world's transactions through one bottleneck, and naive sharding splits security along with the work.
Quai resolves this with two moves. Merged mining lets one hash secure every level of a chain hierarchy simultaneously, so adding chains adds capacity without dividing security. And PoEM — Proof of Entropy Minima — makes consensus deterministic enough that many chains can coordinate without forks, committees, or finality delays.
The result is a network measured for 255,000+ TPS of capacity with ~5 second zone blocks and sub-penny fees, where the marginal energy cost per transaction falls as the network grows.
Proof-of-work doesn't have a throughput limit. Single chains do.
The architecture, mechanism by mechanism
Six mechanisms compose Quai's design. Each links to the full treatment in the docs.
PoEM consensus
Every block's PoW hash encodes how much entropy it removed from the search space. Nodes pick the head by comparing measured entropy, so two simultaneous blocks never split the network — fork choice is instant, objective, and identical everywhere.
PoEM deep dive +The Prime / Region / Zone hierarchy
Zones process transactions (~5s blocks). Regions coordinate zones (~10s). Prime coordinates regions (~20s) and anchors the network. The hierarchy launches focused and expands — up to nine zones across Cyprus, Paxos, and Hydra — when sustained demand triggers expansion.
Hierarchical structure +Merged mining and coincident blocks
Miners hash once and check the result against Prime, Region, and Zone difficulty thresholds at the same time. Blocks that satisfy multiple levels — coincident blocks — knit the hierarchy together and act as trustless bridges between chains.
Merged mining +Sharded address space
An address's leading bits name its home zone, so any participant can route a transaction by reading the address itself. Cross-zone transfers travel as external transactions (ETXs) that propagate through the hierarchy with no custodial bridges.
Address sharding +Dual ledger: QUAI and QI
Each zone runs two ledgers — an EVM account ledger for QUAI and smart contracts, and a UTXO ledger for QI, the energy-priced cash token. Protocol-native conversion links them without wrapping or intermediaries.
Tokenomics overview +Workshares and smooth rewards
Blocks include lower-difficulty proofs called workshares — several per block — which compensate near-miss work, reduce reward variance for small miners, and feed additional measured entropy into consensus.
Mining on Quai +
Research and engineering
Quai's mechanisms are published before they are trusted. PoEM appeared on arXiv in 2023, and its formal security analysis — "A Better Proof-of-Work Fork Choice Rule" — followed in 2024. The protocol implementation, go-quai, is open source, as is the SolidityX compiler for cross-zone contracts and the quais SDK.
For builders, the practical surface is familiar: an EVM with Solidity support up to 0.8.20, a quai_ JSON-RPC namespace, GPU-friendly KawPow mining, and developer tooling documented at docs.qu.ai.
Protocol milestones
2023
PoEM formalized
The Proof of Entropy Minima paper defines entropy-based fork choice — the foundation that lets a hierarchy of chains agree instantly.
2024
Formal security proof
PoEM's security argument is published, showing entropy-minima fork choice is at least as safe as longest-chain while converging faster.
February 2025
Mainnet genesis
The hierarchy goes live with Cyprus-1 processing transactions, ~5 second zone blocks, and open KawPow GPU mining.
2025
Workshares and SOAP in production
Workshare inclusion smooths solo-mining rewards, while SOAP converts merge-mining subsidies from SHA-256, Scrypt, and KawPow chains into QUAI buybacks and burns.
Frequently asked questions
How does Quai Network reach 255,000+ TPS?
Capacity scales horizontally: each zone chain processes transactions in parallel with ~5 second blocks, and the hierarchy adds zones as sustained demand grows. Because merged mining secures every chain with the same work, throughput grows without dividing security — the measured ceiling across the full hierarchy exceeds 255,000 TPS.
What is PoEM and how is it different from normal proof-of-work?
PoEM (Proof of Entropy Minima) keeps PoW mining but changes fork choice: instead of counting blocks and waiting out ties, nodes compare the intrinsic entropy each block's hash removed from the search space. Every node computes the same winner immediately, eliminating forks and giving fast, objective head selection — the property that makes coordinating many chains practical.
How do cross-chain transactions work on Quai?
Addresses encode their home zone in their leading bits. A transaction destined for another zone emits an external transaction (ETX) that propagates through the Region and Prime levels and settles in the destination zone — secured by the same merged-mined proof-of-work, with no multisig or custodial bridge.
Why use proof-of-work instead of proof-of-stake?
PoW ties security to a physical resource outside the system, so influence can't be compounded by holding the token itself, and participation stays permissionless — anyone with a GPU can mine. Quai's bet is that PoW's weaknesses were throughput and energy-per-transaction, both of which the hierarchy addresses: capacity scales by adding chains while one pool of work secures everything.
What are workshares?
Workshares are valid-but-lower-difficulty proofs that blocks include alongside the winning hash — several per block. They pay miners for near-miss work, which smooths reward variance for small operations, and they contribute measured entropy that strengthens consensus.
Is Quai fully EVM-compatible?
Zone chains run an EVM derived from go-ethereum: Solidity contracts up to 0.8.20 deploy unchanged. The differences are at the edges — a quai_ RPC namespace (handled by the quais SDK), zone-aware addresses, and optional SolidityX for contracts that span multiple zones.
Build on the architecture
The docs cover everything from first deployment to cross-zone contracts — and the integrations directory maps your existing tools to Quai.