A relational quantum computer using only two-qubit total spin measurement and an initial supply of highly mixed single qubit states

Abstract

We prove that universal quantum computation is possible using only (i) the physically natural measurement on two qubits which distinguishes the singlet from the triplet subspace, and (ii) qubits prepared in almost any three different (potentially highly mixed) states. In some sense this measurement is a `more universal' dynamical element than a universal 2-qubit unitary gate, since the latter must be supplemented by measurement. Because of the rotational invariance of the measurement used, our scheme is robust to collective decoherence in a manner very different to previous proposals - in effect it is only ever sensitive to the relational properties of the qubits.

TR apologises for yet again finding a coauthor with a ridiculous middle name [12]

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Cited by in corpus (14)

• Cluster-state quantum computation
• Contextuality in Measurement-based Quantum Computation
• Deterministic generation of large cluster states using non-deterministic collective measurements based on quantum Zeno effect
• Quantum information processing via a lossy bus
• Quantum computation via translation-invariant operations on a chain of qubits
• Critical phase and spin sharpening in SU(2)-symmetric monitored quantum circuits
• Entangling spins by measuring charge: a parity-gate toolbox
• Generalized parity measurements
• Optically induced spin to charge transduction in donor spin read-out
• Phase map decompositions for unitaries
• Rotationally-Invariant Circuits: Universality with the exchange interaction and two ancilla qubits
• Unravelling Quantum Dot Array Simulators via Singlet-Triplet Measurements
• Theory of Quantum Circuits with Abelian Symmetries
• Symmetry Protected Quantum Computation