# Bridging From Bitcoin As a ZK Bitcoin solution, the Zulu system must facilitate the seamless transfer of assets between Bitcoin and Zulu. Presently, all well-conceived cross-chain bridge designs incorporate the BitVM framework, exemplified by Robin's BitVM Bridge and ZK Base's ZKByte design. Zulu's cross-chain bridge for Bitcoin will be implemented utilizing the BitVM bridge, ensuring a trust-minimized security level. The BitVM bridge can maintain a 1:1 ratio between the value of zBTC published on Zulu and the value of BTC locked on Bitcoin through a 2-way PEG mechanism. However, a challenge arises when crossing zBTC based on the BitVM bridge—its value remains fixed, equivalent to the value of BTC locked previously. Ordinarily, due to certain transaction behaviors, assets crossed back by regular users may not have a fixed value. To address this scenario, the system supports ordinary users in transferring assets between Bitcoin and Zulu through the mechanism of Atomic swaps. ZBTC crossed via the BitVM bridge can function as a liquidity provider for Atomic swaps in such situations. * More Detail [Peg IN/OUT Overview](/core-concepts/bitvm-zulu/bridging-from-bitcoin/peg-in-out-process.md) [Atomic Swaps Overview](/core-concepts/bitvm-zulu/bridging-from-bitcoin/atomic-swaps.md) --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.zulunetwork.io/core-concepts/bitvm-zulu/bridging-from-bitcoin.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.