Category:Prepare and Measure Network Stage

This stage is the �first to offer end-to-end quantum functionality. Any node here is allowed to prepare one qubit state and transmit the resulting state to any other node, which then receives and measures it. In this case, the other node can either measure the qubit or conclude that it is lost. Transmissions and measurements can be post-selected, a signal that the qubit is lost may be generated instead. For instance, the receiving node is allowed to ignore non-detection events and conclude that such qubits are lost. If the sender can prepare an entangled state of two qubits then this stage also includes the case in which the sender can prepare an entangled state and send the two entangled qubits to two di�erent nodes in the network. This entanglement distribution is also post-selected. However this post selected prepare and measure functionality is not equivalent to transmitting arbitrary qubits over the network. Applications: This stage allows tasks like QKD, where a secure private key can be gener- ated between two nodes, which is secure against any eavesdropper having any kind of computational power. Nodes can have their password veri�ed without leaking it. Another class of protocols in this stage is in the domain of two-party cryp- tography. Here, there is no eavesdropper, but rather Alice and Bob themselves do not trust each other. An example of such a task is secure identi�cation, in which Alice (a potentially impersonating user) may wish to identify herself to Bob (a potentially malicious server or automated teller machine) without revealing her authentication credentials. Provable security can be achieved in this case. Other known protocols in this stage include (position veri�cation) (link here) which is weakened forms of two party cryptographic tasks that can form building blocks, such as imperfect bit commitments (link here) and coin-flipping (link here)