Measurement-based entanglement of spin qubits

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The elementary unit of quantum information is the quantum bit or qubit. Like the classical bit, the qubit is a two-level system but with the ability to exist in a superposition of states. This means it can be in the on and off state at the same time which has profound implications if we consider quantum systems of more than one qubit. Instead of each qubit carrying any well-defined information of its own, the information is encoded in their joint properties. In quantum mechanics, the qubits are described as being entangled. The challenge is to find ways to harness quantum phenomena such as superposition and entanglement to construct a quantum computer that is able to perform computational tasks that are unattainable in a classical context.This project will address this by using an innovative measurement-based approach to quantum computation which makes use of an intriguing quantum mechanical effect by which two spatially separated quantum bits become entangled if a measurement cannot tell them apart. Computation is then achieved by a sequence of measurements on individual qubits that consumes the entanglement - an approach which is entirely different from standard circuit-based quantum computation. The end goal is to demonstrate an all-electrical and scalable distributed quantum processor that does not require any direct interaction between the qubits. Specifically, the project makes use of solid-state electron spin qubits (quantum dots or dopants) to generate entanglement, hyperfine interaction to store quantum information in long-lived nuclear spin states and ultrafast radio-frequency reflectometry readout.