Full Article:Linear-optical approach to encoding qubits into harmonic-oscillator modes via quantum walks | Phys. Rev. Research

It’s true, photons are a strong contender for building future quantum computers! They’re incredibly fast, resistant to noise, and easy to control with existing optical tech. But the big question is, how do you actually perform quantum calculations using them?

One approach involves using the simple harmonic oscillation within specific photon modes as the information carrier for photonic quantum computation, creating what we call photonic qubits. These particular quantum states are known as Continuous-Variable (CV) qubits. The real challenge, though, is figuring out how to achieve fault-tolerant quantum computation when you have multiple photons oscillating in these optical modes.

That’s where the paper, “Linear-optical approach to encoding qubits into harmonic-oscillator modes via quantum walks,” comes in. It introduces a new method using a linear-optical architecture to prepare a special type of qubit: the Gottesman-Kitaev-Preskill (GKP) state.

This GKP state is a highly fault-tolerant qubit within a CV system. This means it can function accurately even if there’s some minor noise or error in the system. The GKP state is considered one of the most critical technologies for building scalable and fault-tolerant photonic quantum computers, making them more reliable and stable in practical operation.