What is Photonic Quantum Computing?

Quantum computing promises to revolutionise how we solve complex problems—but not all quantum computers are built the same. While superconducting qubits (used by IBM and Google) get most of the headlines, photonic quantum computing is emerging as a compelling alternative with unique advantages.

What Makes Photonic Quantum Computing Different?

Traditional quantum computers encode information in superconducting circuits that must be cooled to near absolute zero (−273°C). Photonic quantum computers, by contrast, use particles of light (photons) as qubits.

This fundamental difference leads to several practical advantages:

• Room-temperature operation: Photons don't need extreme cooling, eliminating expensive cryogenic infrastructure
• Lower noise: Photons interact weakly with their environment, reducing decoherence
• Easier networking: Light naturally travels through fiber optics, enabling quantum communication
• Mature manufacturing: Decades of telecom investment in photonic components

How Does It Work?

Photonic quantum computers manipulate light through optical components:

Key Components

• Single-photon sources: Generate individual photons on demand
• Beam splitters: Create superposition states by splitting photon paths
• Phase shifters: Control the quantum phase of photons
• Interferometers: Enable quantum interference for computation
• Single-photon detectors: Measure the output states

Hybrid Photonic-Classical Architectures

At Quantonic, we're developing hybrid systems that combine photonic processing with classical computing. This approach leverages the strengths of both:

• Photonic subsystem: Handles quantum operations where light excels—linear algebra, optimisation, and interference-based computations
• Classical accelerators: GPUs and FPGAs handle data preprocessing, error correction, and result analysis
• AI-augmented partitioning: Machine learning determines which parts of a problem benefit from quantum vs. classical processing

This hybrid approach delivers practical speedups without requiring full fault-tolerant quantum computing.

Applications

Photonic quantum computers are particularly well-suited for:

• Quantum simulation: Modeling molecular and chemical systems
• Optimisation: Solving complex logistics and scheduling problems
• Machine learning: Quantum-enhanced training and inference
• Cryptography: Quantum key distribution for secure communications

The Future of Photonic Quantum Computing

While challenges remain—particularly in generating and detecting single photons reliably—photonic approaches are rapidly advancing. Companies like Xanadu, PsiQuantum, and research initiatives like Quantonic are pushing the boundaries of what's possible.

"The advantage of photonics is that it's naturally compatible with existing telecommunications infrastructure and operates at room temperature. This makes scaling and deployment significantly more practical."

As the technology matures, we expect photonic quantum computing to play an increasingly important role—especially in applications requiring networking and integration with classical systems.