Charles D. Hill

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In this paper we demonstrate how data encoded in a five-qubit quantum error correction code can be converted, fault-tolerantly, into a seven-qubit Steane code. This is achieved by progressing through a series of codes, each of which fault-tolerantly corrects at least one error. Throughout the conversion the encoded qubit remains protected. We found, through(More)
In drug discovery, there is a clear and urgent need for detection of cell-membrane ion-channel operation with wide-field capability. Existing techniques are generally invasive or require specialized nanostructures. We show that quantum nanotechnology could provide a solution. The nitrogen-vacancy (NV) center in nanodiamond is of great interest as a(More)
The exceptionally long quantum coherence times of phosphorus donor nuclear spin qubits in silicon, coupled with the proven scalability of silicon-based nano-electronics, make them attractive candidates for large-scale quantum computing. However, the high threshold of topological quantum error correction can only be captured in a two-dimensional array of(More)
New magnetometry techniques based on nitrogen-vacancy (NV) defects in diamond allow for the detection of static (dc) and oscillatory (ac) nanoscopic magnetic fields, yet are limited in their ability to detect fields arising from randomly fluctuating (FC) environments. We show here that FC fields restrict dc and ac sensitivities and that probing the NV(More)
Quantum communication typically involves a linear chain of repeater stations, each capable of reliable local quantum computation and connected to their nearest neighbors by unreliable communication links. The communication rate of existing protocols is low as two-way classical communication is used. By using a surface code across the repeater chain and(More)
Recent work on fault-tolerant quantum computation making use of topological error correction shows great potential, with the 2d surface code possessing a threshold error rate approaching 1% [1, 2]. However, the 2d surface code requires the use of a complex state distillation procedure to achieve universal quantum computation. The colour code of [3] is a(More)
There are many cases where the interaction between two qubits is not precisely known, but single-qubit operations are available. In this Letter we show how, regardless of an incomplete knowledge of the strength or form of the interaction between two qubits, it is often possible to construct a controlled-NOT gate which has arbitrarily high fidelity. In(More)
While it is known that shared quantum entanglement can offer improved solutions to a number of purely cooperative tasks for groups of remote agents, controversy remains regarding the legitimacy of quantum games in a competitive setting—in particular, whether they offer any advantage beyond what is achievable using classical resources. We construct a(More)
Here we show a mapping between waveguide theory and spin-chain transport, opening an alternative approach to solid-state quantum information transport. By applying temporally varying control profiles to a spin chain, we design a virtual waveguide or "spin guide" to conduct spin excitations along defined space-time trajectories of the chain. We show that the(More)
Starting from the classical notion of an oriented congruence (i.e. a foliation by oriented curves) in R3, we abstract the notion of an oriented congruence structure. This is a 3dimensional CR manifold (M,H, J) with a preferred splitting of the tangent space TM = V ⊕ H . We find all local invariants of such structures using Cartan’s equivalence method(More)