arXiv subjects

Brian La Cour

Publications and source records attributed to Brian La Cour.

4 recordsLinked to original sources

arXiv2025

Gauging practical computational advantage using a classical, threshold-based Gaussian boson sampler

We describe an efficient, scalable Gaussian boson sampler based on a classical description of squeezed quantum light and a deterministic model of single-photon detectors that click when the incident amplitude falls above a given threshold. Using this model, we map several NP-Complete graph theoretic problems to equivalent Gaussian boson sampling problems and numerically explore the practical efficacy of our approach. Specifically, for a given weighted, undirected graph we examined finding the densest k-subgraph and the maximum weighted clique. We also examined the graph classification problem. Compared to traditional classical solvers, we found that our method provides better solutions in a comparable amount of samples for graphs with up to 2000 nodes.

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arXiv2021

Improving Performance of an Analog Electronic Device Using Quantum Error Correction

The use of analog classical systems for computation is generally thought to be a difficult proposition due to the susceptibility of these devices to noise and the lack of a clear framework for achieving fault-tolerance. We present experimental results for the application of quantum error correction (QEC) techniques to a prototype analog computational device called a quantum emulation device. It is shown that for the gates tested (transversal $Z$, $X$ and $SH$) there is a marked improvement in the performance characteristics of the gate operations following error correction using the 5-Qubit Perfect code. In the case of the $Z$ gate, the median fidelity improved from 0.995 to 0.99998, a reduction in the gate error by over two orders of magnitude. Other transverse gates similarly show strong improvements.

quant-ph↗

arXiv2021

A Decoder for the Color Code with Boundaries

We introduce a decoder for the 3D color code with boundaries, which is a variation of the restriction decoder introduced by Kubicka and Delfosse. Specifically, we adapt the lift procedure to efficiently find a correction on qubits adjacent to a boundary. We numerically estimate a threshold of $4\% - 8\%$ for Pauli $X$ errors and a threshold of $0.7\% - 0.8\%$ for Pauli $Z$ errors. Our work is a first step towards characterizing the performance of Bombín's recently proposed "colorful quantum computing."

quant-ph↗

arXiv2019

A Noncoherent Space-Time Code from Quantum Error Correction

In this work, we develop a space-time block code for noncoherent communication using techniques from the field of quantum error correction. We decompose the multiple-input multiple-output (MIMO) channel into operators from quantum mechanics, and design a non-coherent space time code using the quantum stabilizer formalism. We derive an optimal decoder, and analyze the former through a quantum mechanical lens. We compare our approach to a comparable coherent approach and a noncoherent differential approach, achieving comparable or better performance.

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