Startup PsiQuantum has a rough vision of what its million-qubit quantum computer might look like.
“It’s going to look like a big concrete building with a whole bunch of modules,” said Pete Shadbolt, chief science officer. The register.
“Inside those modules are a bunch of silicon chips, half photonic, half electronic, and it’s all wired with the same optical fiber you find today.”
PsiQuantum is betting that silicon photonics will play a central role in its data center-sized quantum computer.
“When you think of quantum computing, you think of milli-kelvin temperatures, atoms flying through space, atomic-scale manufacturing, crazy materials, sci-fi stuff. We have to reusing something that is already manufacturable,” Shadbolt said.
We need to reuse something that is already manufacturable
The system will be based on components made using today’s manufacturing techniques and will not require massive cooling refrigerators, we are told. “If you look at it, as a casual observer, it’s like a big industrial facility with steam coming out of the top,” Shadbolt said.
The big question is whether the ambitious system will ever see the light of day. Although the industry could not provide a specific date for the landing of the system, it hopes that the silicon photonics approach will accelerate commercialization.
PsiQuantum’s approach is one of many quantum architectures being pursued by companies such as IBM, Google and Microsoft, and startups such as Rigetti and IonQ. Quantum computing is highly speculative as these companies attempt to commercialize systems that are heavily grounded in academic concepts. Some quantum systems are available in the cloud. Most companies focus on building scalable and reliable error-correcting systems.
In quantum computers, information is encoded in quantum bits, or qubits. It is hoped that this will allow quantum computers to quickly solve big problems that would be unfeasible for conventional computers. Error correction is necessary to deal with the finicky nature of qubits.
“You build a lattice-like fabric of qubits that are entangled, and then you make measurements on those qubits,” Shadbolt said. These metrics drive the algorithms you want to run “and also implement the error-correcting code, checking for errors and fixing them,” he said.
PsiQuantum’s road to an error-correcting quantum computer specifically involves silicon photonic modulators, optical lattice fibers, and other components.
“The idea is that we’ll take the same manufacturing processes that we used to make transistors. Instead, we’ll make optical waveguides. And we’ll put light inside the chip. And then we can manipulate that light with a toolkit of components,” Shadbolt said.
“At the physical level, it’s really single photons that propagate the same way you would find it in a data center.”
It was show that photon beam splitters can be used to build a universal quantum computing system.
“That’s sort of the starting point,” Shadbolt said. “There’s a whole ton of complexity that turns this into a computer, and it’s going to be a building-scale high-performance computer-like system, and a lot of silicon, a lot of fiber optics in that system.”
Like PsiQuantum, IBM seeks to to construct a one-million-qubit system, slated for release by 2030. But cooling could be a limitation for such a superconducting system, given that it operates at one-hundredth the temperature of deep space, Shadbolt said.
“Photons don’t feel heat. We use some cryogenic cooling systems, but not nearly as many,” Shadbolt said. “Our qubits experience photon loss, they fall off the waveguide but they don’t really feel heat, they don’t feel electromagnetic interference.”
Connectivity is also a consideration in building the data center scale system, as it will not be possible to fit a million qubits on a single chip.
“You need to network chips together. You can’t just use ethernet, you need a quantum interconnect that can send qubits from one chip to the other chip. And the only right way to do that is with light, with photons,” Shadbolt said. noted.
The startup is obtaining system components, such as single-photon sources and single-photon detectors, for its quantum system fabricated through chipmaker GlobalFoundries. PsiQuantum said it already has the control electronics necessary for qubit coherence.
Intel, meanwhile, is aiming for a quantum computer based on quantum dots that can be manufactured in its factories.
Publish or not?
PsiQuantum is still a private company even after Rigetti went public and D-Wave followed suit via deals with blank check companies called SPAC.
PsiQuantum has so far raised $665 million in funding, with the latest round raising $450 million from Microsoft-backed organizations including M12, Blackbird Ventures, and Temasek.
Venture capitalists are pumping billions into quantum computing companies, betting that the technology will one day pay off as conventional computing reaches its limits.
Supernova Partners Acquisition Company II, a finance house that merged with Rigetti in a $1.5 billion deal, said Rigetti’s quantum technology is scalable, practical and manufacturable.
PsiQuantum has customers and partners in the financial, pharmaceutical, energy and automotive worlds to help bring its quantum blueprints to market. The company can sell time on its quantum computer through the cloud. But the high-risk, high-reward nature of the quantum computing space hinges on getting a commercial product to market quickly, Shadbolt said.
“We’re building a data center-like system – we have to put concrete in place, we have to put steel beams in place, and that’s going to take time. But a kind of safe and immediate answer is that the middle of During decade, we’ll have all the manufacturing processes in place. And soon after, we’ll have a quantum computer,” Shadbolt promised.