Quantum computing in server racks: Xanadu's modular approach to scaling up

Canadian Startup Develops Photonic Quantum Computer Designed for Large-Scale Expansion

Key Highlights:

• Xanadu, a Canadian startup, unveils Aurora, a modular photonic quantum computer.
• The system processes information using light-based qubits, differing from superconducting qubit approaches used by Google and IBM.
• The company envisions a scalable data center model with interconnected quantum computing racks.
• Current version of Aurora utilizes 12 qubits, significantly fewer than competitors' systems but with promising advantages.
• Future goals include enhancing photon quality and scaling up to a million qubits by 2029.

Xanadu, a Toronto-based quantum computing startup, has developed a new type of quantum computer designed for scalability. The Aurora system, unveiled recently, utilizes photonic qubits—information encoded in light—to perform complex computations. Unlike quantum computers developed by Google and IBM, which rely on superconducting circuits, Xanadu's approach processes information by directing laser beams through a network of optical components such as lenses and fibers.

The modular design of Aurora consists of four identical units, each housed in a standard server rack slightly larger than an average human. CEO and founder Christian Weedbrook explains that scaling up the system involves connecting thousands of these racks into a large quantum computing network. This contrasts with traditional industry models that treat quantum processors as specialized chips integrated into supercomputers, similar to GPUs.

While Xanadu's latest achievement, published in Nature, marks a significant step forward, it remains an early-stage development. The Aurora system currently operates with 12 qubits across 35 chips—far below the 105-qubit Willow computer from Google and IBM’s 1,121-qubit Condor. Despite this, experts believe photonic quantum computers hold significant potential. Devesh Tiwari, a quantum computing researcher at Northeastern University, likens Xanadu’s progress to constructing a hotel, suggesting they have successfully built individual rooms but still need to demonstrate scalability floor by floor.

Photonic quantum computing offers several advantages. These systems are inherently less sensitive to environmental noise, allowing for longer retention of quantum information. Additionally, integrating photonic quantum computers into networks via conventional fiber-optic cables is relatively straightforward, making them well-suited for future quantum internet applications. Another benefit is their ability to operate at room temperature, unlike superconducting quantum computers, which require extreme cryogenic cooling. However, Aurora's photon detectors still require cooling in a separate room.

Xanadu is not alone in exploring photonic quantum computing; other companies, including PsiQuantum in the U.S. and Quandela in France, are pursuing similar approaches. Meanwhile, alternative quantum computing methods, such as those based on neutral atoms and trapped ions, are also under development. Tiwari believes that no single qubit technology will dominate the industry, but different approaches will likely excel in specific applications. For instance, photonic quantum systems are particularly suited for Gaussian boson sampling, a method that could accelerate solving complex graph problems.

Despite Aurora’s promise, some experts point out the absence of error correction capabilities, which are widely considered essential for practical quantum computing. Quantum information is highly fragile, and error correction mechanisms are crucial for ensuring computational reliability. Weedbrook acknowledges this challenge and notes that Xanadu is working to improve photon quality to reduce data loss, thereby minimizing errors from the outset.

Looking ahead, Xanadu aims to construct a large-scale quantum data center by 2029, featuring thousands of racks and a total of one million qubits. If successful, this vision could redefine quantum computing infrastructure and open the door to new scientific and technological breakthroughs.