Deterministic Generation of Large-Scale Entangled Photonic Cluster State from Interacting Solid State Emitters

Abstract

The ability to create large highly entangled 'cluster' states is crucial for measurement-based quantum computing. We show that deterministic multi-photon entanglement can be created from coupled solid state quantum emitters without the need for any two-qubit gates and regardless of whether the emitters are identical. In particular, we present a general method for controlled entanglement creation by making direct use of the always-on exchange interaction, in combination with single-qubit operations. This is used to provide a recipe for the generation of two-dimensional, cluster-state entangled photons that can be carried out with existing experimental capabilities in quantum dots. arXiv:1801.02599v2 [cond-mat.mes-hall]

Photonic graph state generation from quantum dots and color centers for quantum communications

“…Free evolution for time ∆t = 2π/J yields an x rotation R x (−2πω/J), which combined with z rotations can give arbitrary X gates [64]. As a result, we can implement individual R x (π/2) gates on both spins, even though the system is coupled.…”

“…enabling the implementation of a CZ H ⊗ H gate via a combination of free evolution and single-qubit gates [64]:…”

“…Accordingly, single-qubit rotations interspersed with timed free evolution provide a CZ gate. The realistic case with unequal Zeeman coupling is addressed in [64] and proceeds analogously. Additionally, a careful choice of parameters can remove the need for some of the single-qubit gates.…”

“…The electron coherence time, which is typically T 2 ∼ 1 µs and can be improved further by decoherence pulses [72]. Moreover, the fidelity of the CZ gate can be shown to be 0.99 with frequency errors on the order of 10% for the equal-Zeeman coupling case, and order 0.1% for the unequal case [64]. Table I summarizes the physical requirements for our protocol.…”

Multiplexed Single Photons from Deterministically Positioned Nanowire Quantum Dots

“…As solid-state emitters reach maturity, the next logical step is to interface these sources with larger quantum photonic architectures to promote the scalability and realization of multipartite quantum-information protocols [22]. For example, near-term application of quantum-information protocols such as quantum key distribution [23] (including measurement-deviceindependent schemes [24]), boson sampling [25,26], and photonic cluster state generation for measurement-based quantum computing [27][28][29] all benefit from having multiple streams of indistinguishable photons that can be realized with QDs. However, while each independent ingredient of the fully integrated chip vision has been realized separately, hybrid integration of all components in a fully functional platform is a demanding long-term challenge.…”