Creating and sharing knowledge for telecommunications

Distributed Routing in a Quantum Internet


on 02-10-2019

... Kaushik Chakraborty, from QuTech and the Delft University of Technology (TU Delft), Netherlands

Date & time: Wednesday, Octoberber 2nd, 12:00h
Location: Instituto Superior Técnico, Lisbon, Room 2.8.3, Physics Building

Abstract:
In this presentation, I will talk about routing algorithms which can be used for distributing entanglement in a quantum network with noisy quantum devices. First, we consider two different models for the operation of such a quantum network. One of them is called the
continuous model and the other one is called the on-demand model. In the continuous model, each node in the network continuously generates EPR pairs in the background with some of the other nodes in the network and store them into a noisy quantum memory. This can in principle allows the rapid creation of entanglement between more distant nodes using already pre-generated EPR pairs. In the on-demand model, entanglement production does not commence before a request is made.
Both of the models have their advantages and disadvantages. For example, in the continuous model one can reduce the diameter of the network by pre-sharing longer links in the network. In this talk, I will give one example of the pre-sharing strategy which uses some ideas from
classical complex network theory. This makes the continuous model very efficient. However, routing in the continuous model is a challenging task. The reason is that all of the pre-shared links are temporary in nature. A pre-shared EPR-pair is being consumed after one round of teleportation or it decoheres and eventually becomes unusable after a certain period of time. This makes the network topology in the continuous model dynamic. In this talk, I will mention two distributed greedy routing algorithms and compare their performances in both continuous and on-demand model. More Information..

Realistic resource estimations of fault-tolerant quantum computations


on 27-09-2019

... Alexandru Paler, Johannes Kepler University, Linz, Austria

Date & time: Friday, September 27th, 15:00h
Location: Instituto Superior Técnico, Lisbon, Room P9, Mathematics Building


Abstract:
It is important to reduce the physical resource costs for interesting quantum algorithms as quickly as possible. Small-scale, cloud-based NISQ machines sparked the interest of exact, realistic and non asymptotic resource estimations. It is still uncertain if any valuable quantum algorithm is possible without incorporating costly error-correction protocols that make estimation far more complex. This talk presents the methodology basics and the software tools for estimating the number of physical qubits and the time necessary to execute fault-tolerant quantum computations. More Information..