Abstract
Linear optical quantum computing is beset by the lack of deterministic entangling operations besides photon loss. Motivated by advancements at the experimental front in deterministic generation of various kinds of multiphoton entangled states, we propose an architecture for linear-optical quantum computing that harnesses the availability of three-photon Greenberger-Horne-Zeilinger (GHZ) states. Our architecture and its subvariants use polarized photons in GHZ states, polarization beam splitters, delay lines, optical switches, and on-off detectors. We concatenate the topological quantum error-correction code with three-qubit repetition codes and estimate that our architecture can tolerate a remarkably high photon-loss rate of 11.5%; this makes a drastic change that is at least an order higher than those of known proposals. Furthermore, considering three-photon GHZ states as resources, we estimate the resource overheads to perform gate operations with an accuracy of to be . Compared to other all-photonic schemes, our architecture is also resource efficient. In addition, the resource overhead can be even further improved if larger GHZ states are available. Given its striking enhancement in the photon-loss threshold and the recent progress in generating multiphoton entanglement, our scheme moves scalable photonic quantum computing a step closer to reality.
- Received 30 September 2021
- Revised 28 February 2022
- Accepted 21 June 2022
DOI:https://doi.org/10.1103/PRXQuantum.3.030309
Published 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 Society
Physics Subject Headings (PhySH)
Popular Summary
There are at least two major obstacles to practical quantum computing. One is the gap between realistic error rates in physical systems and fault-tolerant thresholds that can be tolerated by known error correction schemes. The other is resource costs required for quantum error correction that are increasingly heavy for the number of logical qubits. The photonic approach to quantum computing has several remarkable advantages, such as fast operation times and that most operations can be performed at room temperature. However, it is not exempt from the aforementioned obstacles caused by photon losses and limited success probabilities of gate operations. We significantly reduce these practical hurdles.
In our work, using three-photon entangled states, which were recently realized deterministically in an experiment as basic resources, we design an all-photonic architecture that tolerates a remarkably high photon-loss rate of 11.5%. This makes a drastic change that is at least an order higher than those of known photonic proposals. A key idea is to reduce the failure probabilities of gate operations using multiphoton entanglement. Further, considering three-photon entangled states as basic resources, we estimate our scheme to be resource efficient compared with other all-photonic schemes. In addition to these resource states, our scheme uses only non-photon-resolving detectors along with simple linear optical elements, which makes quantum computing feasible entirely at room temperature.
Given its striking enhancement in the photon-loss threshold and the recent progress in generating multiphoton entanglement, our scheme makes scalable quantum computing a significant step closer to reality.
