Category:Quantum Memory Network Stage

In this stage, the end nodes have the capability to have a local memory while allowing universal local control. A crucial di�erence between this stage and the previous one is that we are now able to transfer unknown qubits from one network node to another for example, by performing deterministic tele- portation. Technology that can be used to deterministically relay qubits over long distances by means of large-scale quantum error correction implies the technological capability of realizing a good local quantum memory. Applications: 3 This stage also implies the ability to perform entanglement distillation and generate multipartite entangled states from bipartite entanglement by exploit- ing the ability for local memory and control. An important parameter in application protocols is the number of commu- nication rounds and the number of times information is sent back and forth between two end nodes during the course of the protocol. For useful applica- tion protocols, the storage time needs to be compared with the communication time in the network instead of an absolute time. If the network of nodes are far apart, they exhibit longer memory time to attain this stage and the quality of memory is time dependent. The storage time is related to maximum time it takes for any two nodes to communicate because a stage is attained only if the functionality is available to any two nodes in the network, even the two that are farthest apart.

Applications

This allows the implementation of much more complex protocols that require temporary storage of a quantum state during further quantum or classical communication. Examples include protocols for solving distributed systems tasks. Cryptographic tasks can implemented like allowing clients to make use of these computers securely, without revealing the nature or outcome of the com- putation (secure assisted quantum computation, blind quantum computation). We would only need a quantum internet here which would allow a client to communicate with the computing server. Other cryptographic tasks in this domain are tools such as protocols for the sharing of classical or quantum secrets including veri�able secret-sharing schemes, anonymous transmissions. Other interesting applications outside the domain of cryptography are ex- ploiting long distance entanglement to extend the baseline of telescopes, for basic forms of leader election and for improving the synchronization of clocks.