Cluster-state generation with aging qubits

Abstract

Cluster states for measurement-based quantum computing can be created with entangling operations of arbitrary low success probability. This will place a lower bound on the minimum lifetime of the qubits used in the implementation. Here, we present a simple scaling argument for the T 2 time of the qubits for various cluster state geometries, and we estimate the size of the qubit reservoir that is needed for the creation of mini-clusters.

Translating non-trivial algorithms from the circuit model to the measurement-based quantum computing model

“…Therefore, the first operation performed on the logical state in both cluster states is a C Z operation between qubits 1 and 2. By comparing Equations (16) and (22) we can easily identify this C Z operation as a (−1) ab on each term. The next operations to be performed on the square cluster state are the two C Z gates C Z 14 …”

“…We employ the flowing cluster state approach rather than the static approach in which the entire cluster state is constructed prior to any operations [15]. The flowing cluster state may be preferable to the static cluster states as it doesn't require the ability to store large numbers of photons for long times or the ability to act on arbitrarily large states [16]. Instead a small number of single photons are created and measured in turn.…”

Relative resilience to noise of standard and sequential approaches to measurement-based quantum computation

“…Despite the aforementioned advances, the cluster state itself presents a significant technical challenge: to carry out computation, one has to protect the entangled nodes from various sources of noise long enough not only to assemble the cluster state itself, but also to conduct all of the measurements required. In order to mitigate this issue, it is possible to exploit the fact that it is not necessary to assemble the entire cluster state at the beginning of the computation, but rather it can be continuously built "on the fly" [21][22][23][24][25]. This can be viable in some implementations, in particular with travelling light [20,26], but cumbersome in other relevant contexts that involve stationary systems, such as trapped atoms, ions, or solid-state qubits.…”

Imperfect construction of microclusters

“…We then fuse together imperfect microclusters and determine the accuracy of constructing the fused microclusters also via a fidelity. We note that other aspects of realistic photonic cluster state construction including the need to store cluster states (though imperfectly) during construction and effects of dephasing have been explored elsewhere [13][14][15].…”