Quantum.Tech USA 2024

April, 24 – Cryptography Spotlight | Westin, Downtown April, 25-26, 2024 – Main Conference | Conrad Hotel

Conrad, Washington D.C.

Into the Light: Xanadu’s Vision of a Photonic Future

By: Richard Wordsworth, Contributing Writer
Xanadu’s Nathan Killoran accepts the scale of the company’s vision: in two years, this two-year-old company of around 35 software and hardware engineers is dedicated to building a scalable photonic quantum computer with accompanying software.

“We’re trying to solve monumental technological and scientific challenges,” says Killoran, “It’s quite a big vision; it’s a huge problem to solve.” 

The decision to perform quantum computations using photons rather than electrons is Xanadu’s unique selling point. Although it presents challenges, photonics is also an established field where existing technologies, widely used in telecoms for example, can be leveraged. As Killoran puts it: “The difficult problems we have are different to the problems that other quantum computing companies have.”

One major advantage which Xanadu’s photonic computers would have over electron-based systems is energy efficiency. Where most quantum computers operate in dilution fridges at just above absolute zero, photonic computers can theoretically work happily at room temperature without the risk of decoherence, a huge technological benefit.  

However, like other technologies, there are some physical obstacles, which the Xanadu team must currently code around. Chief among these problems is ‘loss’.

“With photonic quantum computing, you encode information in the quantum states of light," Killoran says. “As you shoot this light down a fibre built onto a chip, there’s some probability that the light will lose amplitude or lose photons. This degrades the quantum computation - and if you have too much loss, it degrades to a point where it’s no longer doing something interesting."

“The nice thing about loss - even though it’s a negative effect overall - is that loss is ‘frozen in’. Once you build the chip, you know exactly how much loss that chip has; it’s not a random process where the loss changes every time you shoot a beam down a chip. So you can then account for that and code your circuits in a way that deals with that known loss.”

Xanadu does all design, testing, integration and deployment of chips in-house, leaving the non-core manufacturing element to the chip foundries. Currently the company has two software offerings: PennyLane and Strawberry Fields.

“Strawberry Fields is basically the programming language or API to work with our model of quantum computation,” says Killoran. “If you want to work on a computer that’s based on light, you can’t use the software that’s available from our competitors, because those are dedicated to a different model of quantum computing. Basically, Strawberry Fields is the first software that targets this light-based model of quantum computing. It has three different simulators that target different use cases;  it means we can take all of the ideas from machine learning and test them on our simulator.”

“PennyLane, on the other hand, we see as more of an application layer. It sits above the different APIs. PennyLane is, essentially, software for doing machine learning on quantum computers, and it’s compatible with different types of hardware.”

There are multiple potential applications for Xanadu; and its software’s focus on machine learning lends itself to some familiar quantum applications, particularly drug design.

“I don’t want to tip our hand too early, because we have some ongoing research projects,” he says. “But think of it like this: drugs are materials. They’re made out of physical building blocks and at a fundamental level they are described by quantum mechanics. So, the strong belief in the field is that if you have a device that is also quantum mechanical, then you can simulate molecules and chemical processes and vibrations - the kinds of things you need to do to understand chemistry at a fundamental level."

“We know the equations, but solving those equations in finite time is a huge barrier. So for a lot of situations, an approximation is perfectly fine. But if you want to get a high fidelity understanding of fundamental chemical interactions between matter and these kind of things, you need a device that doesn’t make approximations: you need a device that accurately represents the quantum chemistry.”

Killoran says that Xanadu hopes to have its first   quantum computer running inside 24 months. In that time, the team will be focusing ever more on the technology’s machine learning applications, laying a foundation on which disciplines like drug discovery can then build. But like many companies operating in the quantum space, Xanadu also has a more personal goal: to build the first chip to show quantum supremacy over classical computers, or what Killoran describes as quantum’s “big bang” moment.

Whether it’s Xanadu or one of its competitors, a company showing quantum supremacy is, Killoran says, a reasonable scenario in the next two years. It will also be the catalyst that begins an explosion in quantum computing uptake, with quantum computers taking on increasing varieties and amounts of grunt-work behind the scenes, separated from commercial users by apps and interfaces in the same way that classical computers are used today to run the machine learning algorithms that power desktop and smartphone apps. “Your mom is not going to have a quantum computer,” Killoran says - but once a quantum solution shown to be scalable, it will become increasingly likely that one is processing her searches, clicks and taps.

“I will hedge by saying this is speculation, and that there are still a lot of challenges to overcome: but we’re aiming towards a model where quantum computers power a lot of computation of very hard problems that are connected to things we’re interested in everyday life. Maybe you won’t have a quantum computer running on your smartphone, but they’re going to be the engine driving a lot of things, just like how right now GPUs are used as engines to drive AI, and AI is something that’s starting to permeate your smartphone and your apps online.”

“Quantum computing will probably have a similar place: it will be the engine driving future development in society.”

For more information email Amit Das directly on amit.das@alphaevents.com

Visit Xanadu's website: https://www.xanadu.ai/