Editing Cross-platform finance (section)

==Blockchain and decentralized Finance==
Decentralized finance is an extreme case in which all the trust is put into cryptography while fully removing third parties such as banks. This area is growing based on the progress of the blockchain technology, the key technical element behind bitcoin and other cryptocurrencies.

The main reason for this development is clear. On the one hand, third parties are weak links in the security chain. Most of the security measures should be concentrated there, which may be difficult to achieve when addressing, for example, emerging financial markets. Decentralization is a way to mitigate the risks while developing new financial tools. On the other hand, increasing the liquidity of digital assets implies having various blockchain technologies that are compatible one with another. This allows to have tools to connect markets one to the other and avoid isolation.

In the case of cryptocurrencies, the most important role of the blockchain is to avoid double spending. How can this security goal be achieved in a world with multiple blockchains? This question is can be phrased in general terms as designing secure cross-chain operations.

The potential consequences of quantum communications on blockchain have been widely studied. One obvious reason is that most implemented blockchains are not secure against attacks by quantum computers. It is possible to design quantum-secure cryptocurrencies using quantum key distribution and quantum digital signatures. More interestingly, quantum money can be used to get better scaling for blockchain, a crucial problem for the sustainability of this technology.
The unforgeability and unclonability of quantum money could be helpful to design secure cross-chain operations. Quantum coins can only be spent once, which seems to offer a solution to the double-spending problem. That would require sending those quantum tokens on quantum networks.