Microsoft, Atom Computing update their quantum computing progress
Source: Ars Technica
Progress reports
Some quantum computing companies we’ve covered have done recent progress updates.
With dozens of companies, from small startups to tech giants, pursuing quantum computing, there’s a steady flow of results as they try to find a path to utility. We typically focus on new technologies and major landmarks, which can obscure the fact that any big success will inevitably have been built on a lot of incremental progress.
The past few weeks have seen two companies release progress reports on how they’re trying to get the technologies closer to general use. None of these represents a major breakthrough, but all are absolutely necessary for the technology to advance. The idea here is to convey the hard work required to move us closer to something useful.
Microsoft and Material‑Science Qubits
Microsoft is one of the few companies pursuing topological qubits, which rely on the exotic physics that emerges when particles are confined to very small dimensions. Their approach uses a thin superconducting wire placed on top of a semiconductor.
- Superconductivity – In a superconductor, electrons pair up into Cooper pairs.
- Odd‑electron wire – If the wire contains an odd number of conducting electrons (i.e., a single unpaired electron), that electron becomes delocalised across both ends of the wire—a hallmark of the topological effect.
From Theory to Experiment
Theoretical work predicted this behaviour, but experimental confirmation proved challenging:
- Early results were retracted (see Nature link).
- Initial devices were very noisy, leading to skepticism about the robustness of the effect.
- Despite setbacks, Microsoft published a roadmap for building qubits from pairs of nanowires (Ars Technica link).
Recent Hardware Update
This week Microsoft announced a substantial performance boost by changing the materials used in its qubits:
| Component | Old Material | New Material | Impact |
|---|---|---|---|
| Superconducting wire | Aluminum | Lead | Reduced noise, longer parity lifetimes |
| Semiconductor | Standard composition | Tin‑doped | Enhanced spin‑orbit coupling with lead |
Parity Measurement
- The device consists of two parallel wires.
- Parity (both wires with an extra electron, both without, or a mixed state) is read out via quantum dots.
- Old system: Parity flipped spontaneously every ≤ 10 ms.
- New system: Parity can remain stable for up to 20 s—a dramatic improvement and a key promise of topological qubits.
Outlook
While the hardware advance is encouraging, several milestones remain:
- Controlled parity manipulation – Demonstrate gate operations on individual qubits and qubit pairs.
- Scalable connectivity – Develop methods to link many qubits for error‑corrected computation.
- Peer‑review validation – The manuscript reporting these results must survive rigorous review.
If the findings hold up, Microsoft’s material‑science bet could prove to be a solid foundation for future topological quantum computers.
Any Atom Will Do
Atom Computing is both a Microsoft competitor and a partner, as its hardware is accessible through Microsoft’s Azure Quantum Cloud service. The companies have also worked together to develop the software and protocols needed to perform error correction on Atom’s hardware.
That’s not “hardware” in the typical computing sense. Most of the solid material involves lasers and optical guides; the computation is done using the nuclear spins of atoms held suspended by an array of laser light. Still, Atom is developing something akin to an architecture in which there’s a storage region, an operations zone, and a collection of backup atoms that can be brought in if one of the others is lost. A configuration of lasers called optical tweezers is used to shuffle atoms among these locations.
In a new manuscript, the company shows just how essential having that reserve of spare atoms can be. To hold their state and keep them in the traps, lasers must be used to cool the atoms, which tend to warm up during operations. The cooling is a slow process, but failure to do so leaves hot atoms able to hop out of the laser traps that hold them in a grid, which obviously introduces errors.
So, Atom had a bit of a catch‑22: it needed to perform operations to do error correction, but those operations made errors more probable.
Its solution was to identify that it could do the measurements needed for error correction in a way that swaps a spare, pre‑cooled atom into a logical qubit. Tests that repeatedly measured the state of a logical qubit (a linked collection of data‑storing and error‑detection qubits) showed a big difference:
- Performing error correction without swapping in cold atoms caused the error probability to rise with each successive measurement.
- Performing the swap kept the error probability roughly constant over time.
That doesn’t mean the error‑corrected qubit was fully stable. Eventually, one of the inevitable errors couldn’t be recovered because too many of its individual atoms changed state at once. However, normal error correction could keep some logical qubits stable for up to 90 rounds.
Again, that’s not good enough for any sort of sophisticated calculation, but it’s a lot closer than the company was before working out this technique.
Correction: an earlier version of this report accidentally included embargoed information.
About the Author
John Timmer is Ars Technica’s science editor. He holds a B.A. in Biochemistry from Columbia University and a Ph.D. in Molecular and Cell Biology from the University of California, Berkeley. When physically separated from his keyboard, he tends to seek out a bicycle or a scenic location for communing with his hiking boots.
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