Optimized compiler for Distributed Quantum Computing

Abstract

Practical distributed quantum computing requires the development of efficient compilers, able to make quantum circuits compatible with some given hardware constraints. This problem is known to be tough, even for local computing. Here, we address it on distributed architectures. As generally assumed in this scenario, telegates represent the fundamental remote (interprocessor) operations. Each telegate consists of several tasks: i) entanglement generation and distribution, ii) local operations, and iii) classical communications. Entanglement generations and distribution is an expensive resource, as it is time-consuming and fault-prone. To mitigate its impact, we model an optimization problem that combines running-time minimization with the usage of that resource. Specifically, we provide a parametric ILP formulation, where the parameter denotes a time horizon (or time availability); the objective function count the number of used resources. To minimize the time, a binary search solves the subject ILP by iterating over the parameter. Ultimately, to enhance the solution space, we extend the formulation, by introducing a predicate that manipulates the circuit given in input and parallelizes telegates' tasks.

Quantum Internet Protocol Stack: a Comprehensive Survey

“…Specifically, the order of generation among different entanglement resources to be swapped does not matter. Also, the order among the different swapping operations at the different intermediate nodes does not matter: they can happen simultaneously or in any other order [29]. Furthermore -for instance, as it happens when entanglement is used for quantum teleportation -the same concept of source and destination is dynamic.…”

“…By performing a Bell State Measurement (BSM) on the two qubits at its side -where each qubit is part of an EPR pair shared with a different network node -the quantum repeater is able to entangle the two network nodes, even though they are not directly interconnected by any quantum link nor they had any previous interaction or direct communication. It is worthwhile to mention, though, that the entanglement swapping requires the output of the BSM -two bits likewise quantum teleportation -must be transmitted from the repeater to at least one of the network nodes for properly recovering the original entangled state [29].…”

“…Differently from the other two considered proposals, the quantum network stack proposed in [82] by Dür et al is based on multipartite entangled states, which are manipulated 29 to fulfill the node requests. More into detail, the authors assume that the network evolves according to three phases: dynamic, static and adaptive.…”

“…Differently from Van Meter's proposal, it is responsible not only for the distribution of entangled states but also for the direct transmission of the quantum particles encoding the informational qubits over the channel, without applying any error correction or entanglement distillation mechanisms. Furthermore, such a layer is responsible for interfacing different physical channels with the memory and data qubits 30 and/or different 29 For further details on the design of the initial multipartite states to be manipulated for fulfilling the communication demands, we refer the reader to [66]. 30 We refer the reader to [5,10] for further details about memory and transmissions strategies.…”

“…Obviously, the definition of physical connectivity can be easily extended to a multi-hop route constituted by several communication links 22. It is worthwhile to note that, thanks to the deferred measurement principle[11,29,64], the transmissions of the two classical bits -and the subsequent post-processing at the destination needed for performing a teleporting operation -can be delayed at any convenient time. Accordingly, in this section we focus on the peculiar connectivity characteristics arising with quantum entanglement.…”