Xanadu and Imec’s Photonic Chips Take On Quantum Scaling and Fault Tolerance

August 18, 2021 by Jake Hertz

Scaling and fault tolerance are just two major challenges facing quantum computing. Hoping to rise to the challenge, imec and Xanadu bet on silicon nitride (SiN) photonic chips.

Quantum computing is a technology that many people believe will completely revolutionize computing as we know it; however, it’s currently far from making a notable impact just yet. One of the significant challenges, scaling, has proved hard to overcome based on conventional electronic approaches, leading many companies to look towards photonics as a solution. 

A potential solution that is being heavily investigated by companies and researchers alike is the use of photonics, namely photonic circuits or chips. 


A silicon-nitride photonic IC manufactured by imec.

A silicon-nitride photonic IC manufactured by imec. Image used courtesy of imec


Yesterday, Xanadu, a quantum computing company, has announced its collaboration with imec to develop photonic chips for scalable quantum computing. This article will aim to scratch the surface of the challenges they face, the solutions they're pursuing, and the partnership's goals. 


Challenges to Quantum Scaling

Before quantum computing can achieve its highly anticipated capabilities, many challenges need to be overcome. 


Current quantum computers can be the size of rooms, as shown by Google's Sycamore quantum computer.

Current quantum computers can be the size of rooms, as shown by Google's Sycamore quantum computer. Image used courtesy of Google


As mentioned, scaling challenges come from the fact that quantum computers require operating at cryogenic temperatures. This temperature requirement is limiting because these cryogenic electronics often interface with control circuitry, typically required to be at room temperature. 

These contradicting requirements create an interconnect bottleneck where many wires are needed to interface the electronics in two vastly different temperatures, thus adding weight, size, and complexity to a quantum computer. All of this is then added on top of the infrastructure needed even to create cryogenic temperatures. 

Another challenge towards quantum scaling is the current lack of quantum computers with a high level of scalable fault tolerance. Conventional quantum computers tend to have very noisy qubits, and leading research suggests that traditional error correction methods are too experimentally challenging to be scalable for larger quantum computers. 

This issue of fault tolerance is what Xanadu, and now imec, is hoping to solve.


Xanadu’s Approach = Photonics 

Seeking to address these issues and many more, Xanadu is betting on photonics. After some exciting momentum, like a room temperature quantum computer, and a sudden flow of investments, and a DARPA grant, Xanadu is primed to keep furthering its goals. 

Photonics, in general, is beneficial because it doesn't need to operate at cryogenic temperatures making it inherently scalable. Moreso, Xanadu is also turning to photonics because of the fault-tolerance it can provide. 


Example of a photonic IC with silicon waveguides.

Example of a photonic IC with silicon waveguides. Image used courtesy of Edmund Optics


Specifically, Xanadu's approach relies on the use of silicon nitride photonics as opposed to conventional silicon. Conventional photonic-based quantum computers rely on single-photon sources made from silicon waveguides, resulting in non-deterministic operation. 

According to Xanadu, using silicon nitride, on the other hand, allows for the generation of qubits based on squeezed states, which is a unique state of light generated by silicon nitride-based photonics. These squeezed states can be deterministically generated, allowing for error-resistant qubits. 

With a possible solution and goal in mind, the next step was to find a way to produce these chips on a large scale. 


Teaming Up for Volume Production

Xanadu is building momentum thanks to its room-temperature quantum computer, a sudden flow of investments, and a DARPA grant, it is primed to keep furthering its goals. To further pursue this path, Xanadu is teaming up with imec for the volume manufacturing of its silicon-nitride photonic chips. 

Currently, imec can manufacture silicon-nitride photonics on 300 mm and 200 mm lines, but this isn't the only reason Xanadu chose to partner with them. According to Xanadu, the real draw was not only their current capacity but the fact that imec continues to look towards the future, with heavy amounts of advanced technology R&D.

Xanadu sees this as crucial to the continued development of its technology, as well as its company. 

Even though quantum computing still has a long way to go, and there is no clear or "right" path yet, photonics certainly seems a promising direction. 

The new collaboration between Xanadu and imec holds promise to accelerate this path and, if successful, the quantum future may be dawning sooner rather than later.



Interested in other quantum computing news? Read more in the articles down below.

IBM Accelerates Germany as a Quantum Hub with EU’s First Quantum Computer

A Cryogenic IC May Be the Answer to Quantum Computer Scalability

The Quantum Internet May Be the Beginning of Ultra-secure Non-binary Networks