Abstract
The scalability of photonic implementations of fault-tolerant quantum computing based on Gottesman-Kitaev-Preskill (GKP) qubits is injured by the requirements of inline squeezing and reconfigurability of the linear optical network. In this work we propose a topologically error-corrected architecture that does away with these elements at no cost—in fact, at an advantage—to state preparation overheads. Our computer consists of three modules: a two-dimensional (2D) array of probabilistic sources of GKP states; a depth-four circuit of static beam splitters, phase shifters, and short delay lines; and a 2D array of homodyne detectors. The symmetry of our proposed circuit allows us to combine the effects of finite squeezing and uniform photon loss within the noise model, resulting in more comprehensive threshold estimates. These jumps over both architectural and analytical hurdles considerably expedite the construction of a photonic quantum computer.Received 9 April 2021Accepted 15 November 2021DOI:https://doi.org/10.1103/PRXQuantum.2.040353Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasMeasurement-based quantum computingOptical quantum information processingQuantum computationQuantum information architectures & platformsQuantum information processing with continuous variablesTopological quantum computingQuantum Information
Highlights
The photonic quantum computing paradigm is well placed to handle the long-term obstacles inherent to engineering scalable quantum computers
The need for robust and stable optical quantum information is met by combining bosonic codes known as Gottesman-KitaevPreskill (GKP) qubits [1] with qubit quantum error correcting codes implemented through measurement-based quantum computation (MBQC) [2,3,4], in a hybrid continuousvariable (CV) and discrete-variable (DV) architecture [5,6,7,8,9]
We find the correctable region for our macronode resource state through Monte Carlo simulations, where each trial comprises of three steps: simulating the complete macronode RHG lattice prepared in Fig. 1, reducing it to the canonical lattice, and performing error correction on the reduced lattice
Summary
The photonic quantum computing paradigm is well placed to handle the long-term obstacles inherent to engineering scalable quantum computers. Gates introduce noise [6,9,10,11]; the requirement of deterministic GKP sources leads to onerous multiplexing costs; and the need for rapid reconfiguration in the linear optics networks is a substantial burden on integrated chips [12]. All of these elements increase the number of optical components seen in each photon’s journey, thereby compounding loss—the most harmful imperfection in a photonic quantum computer. We show the simple trade-off between tolerable finite squeezing noise and uniform photon loss rates for a given GKP failure rate
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