Recent announcements have highlighted the growing presence of major quantum computing companies in the Chicago region, each using a different technology in pursuit of a utility-scale quantum computer.
There’s trapped ions (the basis for the quantum computer IonQ is bringing to the University of Chicago), superconducting qubits (the building block for the IBM Quantum System Two that will power the National Quantum Algorithm Center), and photonic qubits (which is what PsiQuantum is building at the Illinois Quantum & Microelectronics Park.) There’s even a modality—electrons on liquid helium—that is exclusive to the Chicago-based EeroQ.
So why are there so many types of quantum computers? What makes them different? And, perhaps most importantly, what does it mean that these “competing” architectures exist in the Quantum Prairie?
“They aren’t really in competition—each type of quantum computer has its unique strengths, and we see them developing in parallel,” said David Awschalom, the University of Chicago’s Liew Family professor of molecular engineering and physics and the director of the Chicago Quantum Exchange. “The real opportunity comes from leveraging their relative advantages, finding the right tool for the right problem, and building a quantum ecosystem where diverse technologies can advance together.”
Unlike classical computers, which are all constructed more or less the same way, there are many ways to build a quantum computer. Superconducting qubits can calculate particularly fast; trapped ions are exceptionally stable; neutral atoms are especially scalable; and photonic qubits are remarkably well-suited to integration with classical technology and the industrial manufacturing infrastructure for semiconductors.
And nearly all modalities have connections to the Quantum Prairie. Companies are drawn to the region’s deep well of expertise, broad industry base, and integrated discovery-to-deployment approach, as well as to the growing infrastructure and talent pool. About a dozen quantum computing companies have offices in the Illinois-Wisconsin-Indiana region, representing seven different types of architectures. An additional seven quantum computing companies representing five types of architectures are connected to the region as CQE corporate partners.
In addition, the region has connections to dozens of companies focused on quantum sensing, quantum communication, quantum algorithms, potential end-use applications, or the manufacturing of materials or components that are part of the quantum supply chain. It is also home to a 124-mile quantum network; quantum networks, which connect quantum computers like the internet connects classical computers, could connect quantum computers with different types of qubits.
“Creating entangled quantum networks in Chicago and throughout the Midwest may ultimately serve to integrate these disparate computing technologies to create hybrid quantum machines with extraordinary capabilities,” Awschalom said. “And it’s likely that the impact will be beyond anything we imagine today.”
The presence of so many types of quantum computers may sound like a race for supremacy, but experts agree that the quantum future will most likely be “multi-modal.” Different companies will use different qubit modalities for different applications—and perhaps even collaborate on technologies that draw on multiple approaches.
“Different platforms are going to be interacting with one another, learning different things from each other,” said Johannes Pollanen, the chief science officer for Chicago-based EeroQ.
Rising tides lift all quantum ships
The approaches have different technology readiness timelines depending on the application—as shown in a recent Science paper co-authored by Awschalom and a global team of scientists—but they also have commonalities that enable them to learn from and teach one another.
“We’re at the point of maturity that individual breakthroughs in [just one kind of] platform or approach are not enough,” Fermi National Accelerator Laboratory’s Associate Lab Director for Emerging Technologies Panagiotis Spentzouris. “We have to consider how we put all of that together to build something larger, to be able to achieve the full potential of the technology.”
Rather than competing in isolation, companies, research institutions, and national labs are increasingly finding ways to share insights, infrastructure, and talent through consortia like the CQE; coalitions like the Economic Development Administration–designated Bloch Quantum Tech Hub and the Quantum Connected NSF Engines team; and via physical infrastructure like the Illinois Quantum Microelectronics Park.
“As quantum has developed over time, as an industry, that ‘rising tide raises all ships’ mentality applies, and resources become more and more available for each other,” said Jordan Shapiro, president and general manager of quantum networking, sensing, & security at IonQ, during a Chicago Quantum Summit session on Connecting Quantum Domains for Scale. “I’m very excited to see how we continue to raise each other’s ships in the years to come.”
A crash course in qubits
Quantum computing offers the potential to revolutionize fields like medicine, sustainable energy, climate modeling, and cybersecurity. It can solve certain types of problems that stump ordinary classical computers because instead of calculating with bits—switches that can either be 0 or 1—quantum computers calculate with qubits, which can exist in a quantum superposition of 0 and 1. Quantum algorithms can take advantage of the unique properties of quantum mechanics to open up a whole new world of possibilities when it comes to computation.
But while classical bits primarily use transistors to represent their state—0 or 1—quantum bits can be made of atoms, circuits, electrons, and more. Each has different advantages and disadvantages, which is why different companies and groups use different modalities.
Each of the different types have a few common features that make them usable as qubits. They have at least two states that are relatively separate from each other in energy, and that energy is “quantized,” meaning the properties and measurements are confined to a set of values rather than any possible value. (The word “quantum” comes from “quantized.”) An atom, for example, has specific energy levels for its electrons. Electrons in the atom cannot exist anywhere between these energy levels, but they can leap from one to another by emitting or absorbing the exact amount of energy necessary to do so—no more, and no less.
There are other properties that are quantized in a quantum system as well, such as spin—a property inherent to tiny particles such as electrons which has only two possible values: up or down. This makes spin very useful as a representation of 0 and 1 in a qubit.
Using different quantum systems with different quantum states gives them different advantages, and also different challenges. What follows is a brief overview of the most common qubit types used in quantum computing.
Superconducting Qubits: Also called a transmon qubit, superconducting qubits are tiny superconducting circuits. Electric current through these circuits behaves according to the rules of quantum mechanics: its properties are quantized. This means that the quantum circuit has energy levels, much like an atom. The 0 and 1 are represented by the lowest energy level and the second-lowest.
Superconducting qubits can be manufactured using a similar process to the chips used in classical computing, so they were one of the first qubit modalities. They’re also used by some of the classical computing giants such as Google and IBM.
However, they must be kept at millikelvin temperatures—colder than the temperature of outer space—in order to work, requiring state-of-the-art refrigeration techniques. This can pose challenges when it comes to scaling them to make a larger quantum computer.
Other companies that use superconducting qubits include Rigetti, Qolab—whose co-founder John Martinis was awarded the 2025 Nobel Prize in Physics—and D-Wave.
D-Wave’s case is somewhat unique, in that they do not use their qubits in the same way daily computers operate on classical bits, by switching them on/off. Instead, their quantum computers use a process called “quantum annealing,” in which they solve a problem by letting the qubits interact with each other without precisely controlling them, but in such a way that the overall network of qubits will find the lowest possible energy level. This is particularly useful for optimization problems, such as those in the fields of logistics and energy.
Trapped Ion Qubits: Ions are atoms that have an electric charge. They can be trapped in place and manipulated using lasers. The 0 and 1 are represented by the atom’s energy level.
Ions as qubits have an advantage over superconducting qubits in that they are naturally completely identical—there is no concern for quality control or consistent manufacturing processes. This is very important for quantum computing, as all qubits in a quantum computer must be indistinguishable for it to work. They are also very stable compared to some other types of qubit.
IonQ, which recently announced a landmark initiative with the University of Chicago, and Quantinuum are companies that use trapped-ion qubits.
Neutral Atom Qubits: Neutral atoms have no electric charge, unlike ions, but the setup to make them qubits is similar: the atoms are trapped and subsequently manipulated by tightly focused lasers, and the 0 and 1 are represented by the atom’s energy level.
Neutral atom qubits are less stable than trapped ion qubits, but have advantages when it comes to scaling up to large numbers. Atom Computing has a 1225 qubit array of neutral atoms, while the best trapped-ion quantum computers have less than 100. However, direct comparisons of qubit numbers are not necessarily indicative of the quality of the quantum computer—since trapped ion qubits are more stable, they can make more reliable calculations in some cases—but it does demonstrate a difference in scalability.
Companies that use neutral atom qubits include QuEra and Atom Computing, as well as Infleqtion and Pasqal. In 2025, Infleqtion announced that it will establish its quantum computing headquarters in Illinois, and Pasqal announced that it will build its US headquarters in Illinois.
Photonic Qubits: At the quantum level, everything is quantized—including light. In photonic qubits, the 0 and 1 are encoded in a property of individual particles of light, called photons. There are several different properties of light that can be used: polarization, where the 0 and 1 can be, for example, horizontal or vertical polarization, respectively, is by far the most common choice; spatial mode encoding, where the 0 and 1 are represented by what path the photon takes;[MF1] and time-bin encoding, where the 0 and 1 are represented by whether the photon arrives early or late.
Photonic qubits don’t need extremely cold temperatures, and they’re ideal for quantum communication and networking because classical computing networking infrastructure is already built to use photons. They do have some scalability and engineering challenges, as photons are never at rest and must be kept inside fibers or cavities, and material imperfections in these can lead to errors and inefficiency.
PsiQuantum and Xanadu both use photonic qubits in their quantum computers.
Semiconductor Spin Qubits: A quantum dot is a tiny crystal of semiconductor material that can trap a single electron inside. This electron can be made into a qubit, with its spin representing the 0 and 1.
Because quantum dots are extremely small, they can potentially scale to millions on a single chip. There is also already strong and widespread infrastructure for semiconductor manufacturing that can be leveraged. But like superconducting qubits, they are prone to fabrication variability that can cause errors.
Intel and Diraq focus on semiconductor spin qubits.
Topological Qubits: Topological qubits are based on the properties of exotic quantum behavior called Majorana zero modes. Theoretically, the quantum information in this type of quantum computer is stored in the global configuration of qubits rather than in the individual qubits, making it naturally protected from many forms of error and noise. However, definitive experimental proof of Majorana modes in usable devices remains elusive.
Microsoft is the only company working on developing topological quantum computing hardware, although other companies (e.g. Quantinuum) are simulating the quantum topological features on their platforms.
Electrons on Liquid Helium: This modality is unique to quantum company EeroQ, headquartered in Chicago’s Humboldt Park neighborhood. Electron spin qubits are trapped and controlled above pools of superfluid helium. The electrons and the helium are confined in microchannel structures, which are fabricated into silicon wafers. The 0 and 1 are represented by the spins of the electrons.
According to EeroQ, making qubits this way is stable and spatially efficient, with good scalability.
But that still doesn’t mean EeroQ’s Pollanen thinks there will be a single “winner.” After all, apples-to-apples comparisons can be tricky—there is no single measure by which one can say a type of quantum computer is “the best.”
“While I’ve very firmly placed a bet on one particular kind of technology, I don’t think quantum is winner-take-all,” he said. “All of these technologies are going to be successful, and it’s going to be to everyone’s benefit and a real boon to humanity to try to push forward on all of them.”