Squeezing-Enhanced Photon-Number Measurements for GKP State Generation

TL;DR

This paper introduces a new architecture for generating GKP states using quadrature squeezing and probabilistic photon measurements, improving efficiency and noise reduction, and achieving a fault-tolerance threshold of 11.5 dB.

Contribution

It presents a novel teleportation-based squeezing protocol integrated into a time-multiplexed cluster state for high-amplitude cat and GKP states, reducing noise and measurement complexity.

Findings

Achieved 11.5 dB fault-tolerance threshold with RHG surface code

Reduced damping and noise by minimizing homodyne measurements

Implemented dynamic input-state resetting and improved breeding algorithm

Abstract

We present an architecture for the generation of GKP states in which quadrature squeezing operations are used to control the average photon number statistics of probabilistic photon number measurements on Gaussian resource states. Specifically, we present an architecture employing a teleportation-based squeezing protocol and polynomial-gate applications integrated into a time-multiplexed multi-mode cluster state to generate cat states with high amplitudes, which are consequently used to generate GKP states with high quadrature effective squeezing. Compared to our previous work, in addition to using squeezing as a resource, the present architecture reduces damping and noise by minimizing the number of homodyne measurements required in GKP state generation. We demonstrate the effectiveness of these improvements - including dynamic input-state resetting and an improved breeding algorithm - by achieving a fault-tolerance threshold of 11.5 dB cluster squeezing using the RHG surface code for error correction, without requiring active switching or photon-number resource states.