Sweet Scientific Advantage
Let's digest the recent claim by Atom Computing and Microsoft.
Sammy Davis Jr. was “The Candy Man.” His classic song is about a man who mixes everything with love, making it sweet and wonderful. You know it. You love it. You want more of it.
You know what else is sweet? Atom Computing and Microsoft recently published “Microsoft and Atom Computing offer a commercial quantum machine with the largest number of entangled logical qubits on record,” and they used Microsoft’s Discovery Suite. Yeah, yeah, yeah, this is a dad joke, but keep reading for the punchline.
In the meantime, let’s focus on the experiments involving entangled logical qubits. We’re seeing more of this in the news these days, and that’s a good thing. There are a couple of numbers in an article with “largest number” in the title, but I’ve personally seen a larger number elsewhere. So, grab yourself a handful of candy, and let’s fully digest this claim.
Entanglement
While there was indeed an experiment involving 48 logical qubits, and the Atom-Microsoft claim only involves 24, the Atom-Microsoft team claims two distinctions. First, they created a GHZ state, which means that they entangled all 24 of these logical qubits. Second, their result was “below threshold,” which means that the logical qubits outperformed the physical qubits, a critical milestone for all quantum error correction (QEC) experiments. They did this by using a 4-2-2 code, which means that they used only two physical qubits per logical qubit.
Computation
The GHZ state showed the logical qubits could be entangled, but the team then ran an algorithm. They used 28 logical qubits this time, and performed error correction while executing the textbook Bernstein-Vazirani algorithm. To demonstrate that the system actually works, they used a 4-1-2 code, which means that they used four physical qubits per logical qubit. They used 112 atoms in total. Importantly, the computation was also “below threshold.”
Step-by-Step Advantage
These were, admittedly, the minimum viable experiments involving logical qubits. The goal is to keep improving the quantity and quality of the logical qubits until they reach a regime where there is “scientific advantage.” They will then turn to applications and pursue “commercial advantage.” While the quantum industry’s publicly-stated goal is commercial advantage, a scientific advantage will be realized well before, and is still extremely interesting. No one will know where either line is until it is reached, but the team is pointing out that there is more than one line to cross.
Accessibility
The most interesting revelation is that Atom-Microsoft is making logical qubits available now. You can’t use them through the Azure Quantum cloud, but if you purchase an AC1000, it’ll include Azure Elements, which includes HPC and AI integration and your very own logical qubits. The AI component is meant to help complete novices work with the system, getting them up to speed simulating molecules and so forth. The idea is to abstract away the quantum information science and allow domain experts to focus on the problems at hand. It also includes figuring out which parts of your computation should use HPC and which parts should use quantum.
I’m not going to rehash the plethora of reasons why organizations might want a quantum computer in-house, but here’s a novel one for you: they don’t want their lines cut by a ship.
Conclusion
I promised a punchline, but with a “dad joke” disclaimer. If you could use Microsoft’s Discovery Suite to demonstrate scientific advantage on Atom Computing’s neutral atom quantum computers, you could call it, “Discovery, sweet!”
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