Valued at $22.5 billion, PsiQuantum's path to a million quantum bits

Who is the world's most money-sucking quantum computing company? It has to be PsiQuantum - a three-year money-sucking frenzy of $665 million (RMB 4.7 billion) and a valuation of $3.15 billion (RMB 22.5 billion), making it the most-funded quantum computing startup (not including IPOs). PsiQuantum has not actually launched any products yet, but why has it attracted investors, including Microsoft? The reason lies in its million-quantum-bit promise.

 

PsiQuantum's path to a million quantum bits began in 2009, when Jeremy O'Brien, a professor at the University of Bristol in the UK, published a research paper describing how to repurpose on-chip optical components originally developed by the telecommunications industry to manipulate individual particles of light and perform quantum manipulation.

 

By 2016, building on earlier photonic research, O'Brien and his three academic colleagues, Terry Rudolph, Mark Thompson and Pete Shadbolt, created PsiQuantum.

 

The founders agreed that building a useful-sized quantum computer using traditional methods would take too long. At the start of the company, the PsiQuantum team established the goal of building a fault-tolerant optical quantum computer with millions of quantum bits. They also believed that the only way to create such a machine was to build it in a semiconductor foundry.

 

Jeremy O'Brien

 

01Receiving strong capital support

 

About two years ago, PsiQuantum secured $150 million in Series C funding, bringing the company's total investment up to $215 million. That level of funding meant there was a lot of interest in the potential of the quantum devices PsiQuantum was building: at the time, PsiQuantum was operating in stealth mode, so little information was available about its research. It wasn't until after securing a $450 million Series D round of funding last year that PsiQuantum disclosed more information about its technology.

 

Just a few weeks ago, the U.S. government awarded a joint $25 million grant to PsiQuantum and its manufacturing partner GlobalFoundries (Lattice) for the tooling and further development of its optical quantum computer. With Ge-core means high-quality chips, as it is one of three Tier 1 fabs in the world.

 

PsiQuantum, which is currently valued at $3.15 billion, is following a quantum roadmap with unique technologies, components and processes of its own design to build a million-scale general-purpose silicon optical quantum computer.

 

PsiQuantum chips from Ge-chip

 

02Optical Quantum Bits Technology Route

 

Classical computers use digital bits to encode information, representing 0 or 1. Quantum computers use quantum bits (qubits), which can also represent 1 or 0, or a quantum superposition of some number between 0 and 1 at the same time. There are various quantum bit technologies. IBM, Google and Rigetti use quantum bits made from small loops that become superconductors when subjected to very low temperatures; Quantinuum and IonQ use quantum bits formed by removing an outer valence electron from an atom of ytterbium; Atom Computing uses isotopes of strontium to create neutral atomic spin quantum bits.

 

Light is used for various operations in superconductors and atomic quantum computers.PsiQuantum also uses light and turns infinitely small photons into quantum bits. Of the two types of photonic quantum bits: compressed light and single photons, the technique chosen by PsiQuantum is the single photon quantum bit.

 

Using photons as quantum bits is a complex process. It is complex to determine the quantum state of a single photon among trillions of photons with different frequencies and energies

Pete Shadbolt

 

Dr. Pete Shadbolt is the co-founder and Chief Scientific Officer of PsiQuantum. His responsibilities include overseeing the application and implementation of the technology, as well as the science-related policies and procedures that are critical to PsiQuantum's success. After receiving his PhD in experimental optical quantum computing from the University of Bristol in 2014, he worked as a postdoctoral fellow at Imperial College, researching the theory of optical quantum computing. While at Bristol, he demonstrated the first ever variational quantum instanton solver and the first publicly available quantum processor API. Award.

 

Dr. Shadbolt explained that detecting a photon from a beam of light is similar to collecting a specified drop of water from the widest part of the Amazon River's volume.

 

"This process takes place on a chip the size of a 25-cent coin," said Dr. Shadbolt, "and extraordinary engineering and physics are taking place inside the PsiQuantum chip. We are continually improving the fidelity of the chip and the performance of the single-photon source."

 

But no photon is good enough. There are strict requirements for the photons used as quantum bits: consistency and fidelity are critical to the performance of an optical quantum computer. Therefore, each photon source must have high purity, proper brightness, and produce consistent, fully homogeneous photons.

 

03Selecting Lattice as a partner

 

 

A year ago, when PsiQuantum announced its Series D funding round, the company revealed that it had entered into a previously undisclosed partnership with Lattice. Out of the public eye, the partnership has been able to build a first-of-its-kind manufacturing process for optical quantum chips. This manufacturing process produces a 300mm wafer containing thousands of single-photon sources, and a corresponding number of single-photon detectors. The wafer also contains an interferometer, beam splitter and phase shifter. To control the photonic chip, an advanced electronic CMOS control chip with about 750 million transistors was also built at the Gecko factory in Dresden, Germany.

 

04Advantages of photonics

 

Each quantum bit technology has its own set of advantages and disadvantages. there are several reasons why PsiQuantum chose to use photons to build its quantum computer.

 

photons are not affected by heat and most photonic components operate at room temperature.

PsiQuantum's superconducting quantum photon detectors require cooling, but they operate at temperatures about 100 times higher than superconducting quantum bits.

optical quantum bits are compatible with fiber optic networks, allowing easy routing of photons between local devices

photons are unaffected by electromagnetic interference.

Another major advantage of photonic quantum bits worth highlighting is the ability to maintain the quantum state for a relatively long period of time. As an example of the coherence of light, light emitted by distant stars and galaxies reaches Earth with its original polarization state intact, despite propagating for billions of years. The longer a quantum bit can maintain its polarized quantum state, the more quantum operations it can perform, which makes quantum computers more powerful.

 

05Why start with a million quantum bits?

 

"We believe we have cracked the code for building a million quantum bit quantum computer," says Dr. Shadbolt, "and although this is a huge number, the secret seems simple enough. All we had to do was use the same process as putting billions of transistors into a cell phone. We don't think a large quantum computer will exist in our lifetimes unless we figure out how to build it in a semiconductor foundry. That idea has become a reality. We're now building quantum chips right next to laptop and cell phone chips on a 300-mm platform at Ge-core."

 

According to Dr. Shadbolt, PsiQuantum has made great progress with its custom manufacturing line. Surprisingly, building million-scale quantum machines in a foundry has many of the same non-quantum issues as assembling a classical supercomputer: including chip yield, reliability, high-throughput testing, packaging and low-temperature cooling.

 

"From our first Lattice core announcement to now, we've produced a lot of silicon," said Dr. Shadbolt, "We've done a total of seven 'tape-outs,' and now we see hundreds and hundreds of silicon wafers coming through our doors. We are making significant investments in packaging, assembly systems, integration and fiber connections to ensure the highest efficiency of light flowing into and out of the chips."

 

PsiQuantum is conducting extensive ongoing research as well as continuously improving the performance of photonic components and processes. In addition to high-performance optical components, the technology that enables the process is also very important. Several enablers include optical switches, fiber-to-chip interconnects, and bonding methods.

 

"At Lattice, we have greatly improved the efficiency of our photon detectors in the last few downstreams," explains Dr. Shadbolt, "and we have been working hard to prevent fewer and fewer photons from being lost from the system. In our most recent chips, we've also pushed waveguide loss to extremely low levels."

 

"There's a lot of innovation involved. Our single-photon source is a good example. We shine a laser directly into the chip to run a single photon source. The laser is about a trillion times more intense than the single photon we need to detect, so we have to attenuate the light on that chip by a factor of about a trillion."

 

Dr. Shadbolt credits the success of PsiQuantum's fabrication to the Lattice core. He knows from experience that there is a huge difference between a Tier 2 fab and a Tier 1 fab like Lattice. Building the chips PsiQuantum needs can only be done with extremely mature manufacturing processes.

 

"PsiQuantum has two demanding requirements. We need a large number of components, and we need those components to consistently meet extremely demanding performance requirements. There are very few partners in the world that can reliably deliver on such requirements, and we have always known that partnering with an established manufacturer like Gercore is key to the success of our strategy."

 

This partnership is also beneficial to Gracore, as it gains additional experience with new technologies by adding PsiQuantum's photonic processes to its foundry.

 

06The light is on the horizon: optical switches

 

According to Dr. Shadbolt, the initial question of whether a large number of quantum devices could be built in a foundry was no longer an issue, as its silicon output had routinely demonstrated. However, inserting new devices into the manufacturing process has been difficult: it is slow and very expensive. The nanowire single-photon detector is an example of a development that came directly from a university lab and was inserted into a manufacturing process.

 

PsiQuantum's semiconductor roadmap has only a few projects left to complete. Because a million quantum bits do not fit on a single chip, quantum computers will require multiple quantum processor chips interconnected by optical fibers and facilitated by ultra-high performance optical switches to allow remote transmission and entanglement of single photon operations between chips.

 

"All that's left is the optical switch," Dr. Shadbolt said, "and you might ask why the optical quantum computing folks have never built anything at any scale. Or why haven't they ever demonstrated very large entangled states? The reason is that it requires a special optical switch that has to have very high performance, better than any existing state-of-the-art converters such as those used in telecommunication networks: it's a classical device whose only function would be to transmit light between waveguides, but it has to do it with very low loss and very high speed. It has to be a very, very good optical switch."

 

Photoelectric switch (photoelectric sensor)

 

If you can't buy it, then you have to manufacture it yourself.

 

For PsiQuantum, implementing an optical switch with the correct specifications was a project that could only succeed and not fail. Since no commercial optical switch existed that met the application requirements, PsiQuantum had no choice but to build one. Over the past few years, its management has been investing heavily in developing a very high performance optical switch.

 

I believe this is one of the most exciting things PsiQuantum is doing," explains Dr. Shadbolt. Building an extremely high performance optical switch is the next big thing on our roadmap. We believe it is the key to unlocking the enormous promise of optical quantum computing."

 

07Summary and Outlook

 

 

PsiQuantum was founded on the belief that photonics is the right technology for building fault-tolerant quantum machines with millions of quantum bits, and that the right way to do it is based on semiconductor fabrication. In contrast to the NISQ quantum computer, the company's founders wanted to avoid building progressively larger and larger machines over time.

 

Considering the overall process required to build a million quantum bit quantum computer, its high level of complexity, and the lack of proven tools and processes, PsiQuantum has made amazing progress since the company was first founded.

 

It has forged a true partnership with one of the world's best foundries, produced seven chips off the assembly line, and funded to build a first-of-its-kind wafer fabrication process to incorporate superconducting single-photon detectors into a common silicon photonic chip. And today, it is tackling another challenge, building an optical switch to fill a gap where the desired product does not exist.

 

Not surprisingly, the ultra-high performance optical switch is a key part of PsiQuantum's plan to build a scalable million-quantum computer. Other quantum companies are planning to integrate similar optical switch technology to scale modular QPU architectures within a decade. the high-performance optical switches being developed by PsiQuantum could one day connect tens of thousands of quantum processing units in future million-quantum-bit quantum data centers. As a standalone product, it could also be a source of additional revenue should PsiQuantum choose to bring it to market.

 

Once the optical switch is fabricated, it will need to be enabled into the Lattice manufacturing process. This is the final step needed to complete PsiQuantum's foundry assembly process, and then it will be ready to produce optical quantum computer chips.

 

However, even with a complete end-to-end manufacturing process, building a complete fault-tolerant quantum computer will take a significant amount of time, and PsiQuantum will still build a complete quantum computer around the chips produced by Lattice. To do so, it will need a trained workforce and a location and infrastructure that can assemble, integrate, test and distribute large quantum computers.

 

Based on the post-fab workload, the development of optical switches, and the remaining assembly, and assuming no major technical issues or delays, it is believed that PsiQuantum will be able to deliver an optical quantum computer of any size after mid-decade.

 

To that end, Dr. Shadbolt said, "While the optical switch will clearly be a very powerful general-purpose technology that will be of interest to others, we are not interested in its general-purpose use. We are only interested in the fact that it will allow us to build a quantum computer that surpasses all the supercomputers on the planet - that is our only goal."

 

Reference links：

https://www.forbes.com/sites/moorinsights/2022/09/21/psiquantum-has-a-goal-for-its-million-qubit-photonic-quantum-computer-to-outperform-every-supercomputer-on-the-planet/?sh=4ead8e758db3