Caltech Scales Neutral-Atom Qubits to 6,100 with Tweezers

It has been about four decades since optical tweezers were developed, and they continue to revolutionize physics, biology, and medicine to this day.

Optical tweezers are a remarkable tool that can pick up and move microscopic objects, such as cells, atoms, molecules, and droplets, without touching them. 

These tools use focused lasers to manipulate objects. By using a highly focused beam of light, they are capable of holding microscopic and sub-microscopic particles stable in three dimensions.

The beam is focused by a high-quality microscope into a spot, creating an ‘optical trap’ that holds a particle. This particle experiences forces consisting of scattering light and gradient forces due to its interaction with the light.

Developed by American physicist Arthur Ashkin in 1986, who received a Nobel Prize in Physics for it in 2018, optical tweezers enable scientists to study single bacteria, a sperm cell, strands of DNA, the interaction of single particles with light, and much more.

Today, these scientific instruments form the foundation for many leading experiments in simulation and quantum computing. 

For instance, scientists from the Department of Experimental Physics and the Institute of Quantum Optics and Quantum Information (IQOQI) have recently trapped single erbium atoms¹ in optical tweezer arrays for the first time, expanding the use of these tools beyond simple systems to more complex quantum experiments.

These kinds of experiments, which trap tens to hundreds of atomic qubits, have recently achieved arrays of about one thousand atoms.

Scaling this to thousands of atomic qubits with low-loss, long coherence times, and high-fidelity imaging, which is critical for making progress in quantum error correction, however, has been a big challenge.
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However, this has now been experimentally demonstrated by Caltech researchers. They have successfully trapped 6,100 neutral atoms in approximately 12,000 sites using an array of optical tweezers. At the same time, they exceeded the “state-of-the-art performance for several metrics that underpin the success of the platform,” noted the team.

The researchers demonstrated a coherence time of 12.6(1) seconds, which is a record for hyperfine qubits in an optical tweezer array. Lasting for about 23 minutes, they achieved a record-high imaging survival of 99.98952(1)% with an imaging fidelity of over 99.99%. 

According to the team, these results suggest that universal quantum computing could soon become a reality. 

Why Error Correction Dominates Quantum Computing’s Roadmap

Quantum computing has captured the interest of researchers and companies worldwide. 

According to analysts at BofA, the quantum computing market is expected to reach a valuation of approximately $4 billion by the beginning of the next decade. 

The “promise of quantum computing is real,” said the analysts in a note to clients, adding that there are still several obstacles to the technology’s growth, and once these are overcome, “we expect a much more meaningful inflection in revenues.”

Supporters of quantum computing highlight its potential to transform finance, healthcare, logistics, cybersecurity, material science, and artificial intelligence. 

Just this week, HSBC Holdings said that it has achieved a world-first breakthrough in using quantum computing in financial markets. The London-headquartered bank used IBM’s Heron quantum processor in bond trading, which yielded a 34% improvement in predicting the likelihood of a bond trading at a certain price. 

Quantum processing was applied to an anonymized set of European bond trading data, where it showed the ability to significantly enhance the market’s efficiency.

Practical applications of quantum technology in other sectors are yet to be firmly established, though, with critics arguing that not only is the quantum computer revolution far off, but also limited.

For instance, late last year, Google released a new chip called Willow that it said marks a major breakthrough in the field of quantum computing, but noted that the benchmark used to measure its performance has “no known real-world applications.²“ 

Still, McKinsey estimates the value of the quantum technology market can climb as high as $100 billion within a decade.

These numbers are based on the anticipation that certain problems can’t be solved by classical computers but can easily be handled by quantum computers, helping us understand and manipulate other quantum systems. 

However, currently, quantum computing is facing significant challenges in terms of decoherence, which renders qubits fragile and prone to errors. This, in turn, makes the costly fault tolerance critical for reliable quantum computing.

Qubits or quantum bits are equivalent to bits in classical computers. But while classical bits are always either one or zero, quantum bits can be both at the same time until their state is measured, and the states of multiple qubits can also be entangled. 

These two phenomena, superposition (the ability for a qubit to exist in multiple states simultaneously) and entanglement (the ability of qubits to be linked and share the same state regardless of distance), give quantum computers capabilities that classical computers don’t have.

Both of these, however, are really fragile states that can easily be destroyed by the slightest interaction with the environment.

From electromagnetic interference to changes in temperature, environmental factors can collapse those properties, leading to inaccurate results. So, this fragility is one of the biggest obstacles to scalable and powerful quantum computing, and thus, a lot of research in the field is focused on quantum error correction (QEC).

One of the ways researchers are compensating for the fragility of qubits and correcting errors is by building quantum computers with extra, redundant qubits. This means a robust quantum computer will have hundreds of thousands of qubits.

Caltech’s Record-Breaking Neutral Atom Array Balances Quantity & Quality

Working towards building a quantum computer with lots of qubits to correct any errors, a team of researchers at Caltech has set a record by creating the largest qubit array that’s been assembled.

A total of 6,100 neutral-atom qubits have been confined in a grid using lasers. Previously, this kind of array only contained hundreds of qubits.

Published in Nature, the study titled “A tweezer array with 6100 highly coherent atomic qubits³” details the milestone, which utilized neutral atoms. 

Neutral atoms are atoms with no net electric charge. So, the number of protons is the same as that of electrons. 

By exploiting their internal energy levels, researchers can use neutral atoms as qubits. Energy levels can be controlled and manipulated using lasers and magnetic fields to perform specific operations.

Being neutral, the atoms don’t interact strongly with each other, making it possible to trap large arrays of atoms and enabling the construction of large-scale quantum processors. Moreover, neutral atoms exhibit long coherence times, another factor making them beneficial for quantum computation.

But, of course, there are challenges in terms of the need for precise control over trapping, cooling, and manipulation.

“This is an exciting moment for neutral-atom quantum computing. We can now see a pathway to large error-corrected quantum computers. The building blocks are in place.”

– Principal investigator of the research, Manuel Endres & a professor of physics at Caltech

Led by Caltech graduate students Hannah Manetsch, Gyohei Nomura, and Elie Bataille, the study used optical tweezers to trap thousands of individual cesium (Cs) atoms in a grid. 

To build the array of atoms, they split a laser beam into 12,000 tweezers, which held a total of 6,100 atoms in a vacuum chamber. “On the screen, we can actually see each qubit as a pinpoint of light,” said Manetsch. “It’s a striking image of quantum hardware at a large scale.”

While the team was able to make a new record in scale, this quantity didn’t come at the cost of quality, as they even achieved long coherence times.

The team was able to keep these qubits in superposition for about 13 seconds, which is about ten times longer than what similar arrays have achieved previously. Moreover, they were able to manipulate individual qubits with an accuracy as high as 99.98%.

According to Nomura:

“Large scale, with more atoms, is often thought to come at the expense of accuracy, but our results show that we can do both. Qubits aren’t useful without quality. Now we have quantity and quality.”

Furthermore, the team showed that they can move the atoms hundreds of micrometers (μm) across the array while still maintaining superposition. Think of it like balancing a glass of water while running.

“Trying to hold an atom while moving is like trying to not let the glass of water tip over. Trying to also keep the atom in a state of superposition is like being careful to not run so fast that water splashes over.”

– Manetsch

This ability is a key feature of neutral-atom quantum computers, as it enables more efficient error correction compared to superconducting qubits.

The research shows neutral atoms to be a strong candidate for helping us implement quantum error correction at the scale of thousands of physical qubits, which is the next major achievement for the field.

“Quantum computers will have to encode information in a way that’s tolerant to errors, so we can actually do calculations of value. Unlike in classical computers, qubits can’t simply be copied due to the so-called no-cloning theorem, so error correction has to rely on more subtle strategies.”

– Bataille

With the superposition state achieved, which plays a crucial role in information processing and storage, the team will now work on entanglement, for which they will connect the qubits in their array, allowing particles to behave as one. 

By achieving the state of entanglement, quantum computers will be able to carry out full quantum computations and simulate. By harnessing entanglement, researchers will also be able to make novel scientific discoveries.

“It’s exciting that we are creating machines to help us learn about the universe in ways that only quantum mechanics can teach us.”

– Manetsch

New Error-Suppressing Architectures & Hyper-Entanglement Results

Endres and his team have been working on quantum computing for a long time now. He specializes in controlling single atoms using optical tweezers in order to study fundamental properties of quantum systems. 

Besides the record-breaking quantum system controlling over 6,000 individual atoms, his team’s experiments have led to new techniques for erasing errors in quantum machines and a new device that can provide the world’s most precise clocks.

In May this year, they published a study⁴ that tackles the problem of atoms’ jiggling motion, which makes it difficult to control the system. What they have done is they have used the very problem to encode quantum information.

“We show that atomic motion, which is typically treated as a source of unwanted noise in quantum systems, can be turned into a strength.”

The study’s co-lead author, Adam Shaw

Their experiment encoded quantum information in the atoms’ motion and led to a state of hyper-entanglement.

This means the individual electronic states and states of motion of the hyper-entangled atom pairs were correlated. Their demonstration, the first of hyper-entanglement in massive particles like neutral atoms or ions, further implies that even more traits could be entangled simultaneously.

“This allows us to encode more quantum information per atom,” Endres said. “You get more entanglement with fewer resources.”

For their experiments, they cooled down an array of individual alkaline-earth neutral atoms trapped inside optical tweezers, demonstrating a new form of cooling via “detection and subsequent active correction of thermal motional excitations.”

The team is essentially measuring the motion of each atom and then, depending on the outcome, applying an operation atom-by-atom.

The technique caused the atoms to come to almost a total standstill. The atoms were then induced to oscillate with a 100-nanometer amplitude, which excited them into two distinct oscillations at the same time, causing the motion to be in the superposition state. 

The individual atoms were then entangled with partner atoms, which were further hyper-entangled to correlate the atoms’ motion and electronic states.

“Basically, the goal here was to push the boundaries on how much we could control these atoms. We are essentially building a toolbox: We knew how to control the electrons within an atom, and we now learned how to control the external motion of the atom as a whole. It’s like an atom toy that you have fully mastered.”

– Endres

In another study from Caltech, a team of scientists based at the Caltech Center for Quantum Computing on the university’s campus demonstrated a new quantum chip architecture⁵ designed to suppress errors. 

“For quantum computers to be successful, we need error rates to be about a billion times better than they are today,” said Oskar Painter, head of quantum hardware at AWS and a professor of physics at Caltech. While error rates are going down, that is happening at a slow rate, “about a factor of two every two years,” so, to accelerate this process, they are developing a new chip architecture, though it’s “an early building block.”

The researchers are using cat qubits, which have significantly reduced bit-flip errors, with phase-flip errors being the only ones left to correct. This means the researchers can use a repetition code. In their new chip called Ocelot, a classical repetition code means no need for as many qubits to correct errors.

“We have demonstrated a more scalable architecture that can reduce the number of additional qubits needed for error correction by up to 90 percent.“

– Fernando Brandão, a professor of Theoretical Physics at Caltech and director of applied science at AWS

To achieve this, the Ocelot chip combines five cat qubits, special buffer circuits to stabilize their oscillation, and four supporting qubits to detect phase errors. The repetition code has been found effective at catching the phase flip errors, which improves as the code increases from three to five cat qubits.

Investing in Quantum Tech

Now, one of the purest quantum computing plays in the market is IonQ (IONQ +0.27%), which takes the trapped-ion approach to make the technology a reality. What really makes it stand out is the high-fidelity gates, integration with major cloud platforms, aggressive acquisitions, and strong patent growth, though scaling costs present a big challenge.

IonQ (IONQ +0.27%)

Founded a decade ago based on years of research at the University of Maryland and Duke University, IonQ is developing trapped-ion quantum computers. The aim of the company is to bring this technology into commercial, industrial, and academic applications. 

For this, the company is focused on ionized atoms, which it believes can enable its computers to perform more sophisticated calculations longer and with fewer errors.

Just this month, IonQ claimed to have achieved over 99.9% two-qubit gate fidelity on its barium development platforms, taking it closer to its commercial system, IonQ Tempo.

This milestone “marks a critical threshold for enterprise-grade systems,” said  IonQ’s SVP of Engineering and Technology, Dean Kassmann, noting that “the better the native gate fidelity, the less error correction in all forms that is required. Higher fidelity is also essential for faster, more accurate quantum applications.”

The use of barium ions as qubits is a shift from ytterbium ions that the company worked on for most of its history. Barium ions have been chosen for their increased gate speeds, higher native fidelity limit, better stability, lower state preparation/measurement (SPAM) errors, and superior overall performance. 

IonQ also boasts a robust portfolio of patents that has now surpassed 1,000, which it says positions the company to develop scalable, high-performance, cost-effective systems, accelerating its timeline for unparalleled commercial quantum advantage.

As of Sep 29, 2025, IONQ closed at $64.26 (all-time high $75.14 on Sep 23, 2025). That’s about 7.4× above the $8.74 close on Sep 30, 2024. Year-to-date performance varies by source window but is broadly ~+50–90%. Market cap is roughly $20–22B.

The company has an EPS (TTM) of -2.02 and a P/E (TTM) of -33.35.

As for its financials, IonQ reported $20.7 million in revenue for the second quarter ended June 30, 2025. Net loss was $177.5 million. Cash, cash equivalents, and investments at the end of the period were $656.8 million.

During this quarter, the company strengthened its balance sheet through the largest equity investment from a single institution in the industry. IonQ also completed the acquisition of quantum interconnect company Lightsynq and space tech company Capella, and proposed the acquisition of Oxford Ionics for $1.075 billion.

“The combination of IonQ hardware and software expertise and Oxford’s implementation of ion-trap-on-a-chip provides the team, IP, technology, and momentum to achieve 800 logical qubits in 2027 and 80,000 logical qubits in 2030.”  

– CEO Niccolo de Masi

In the second quarter, IonQ reported achieving up to a 20× speed-up in a quantum-accelerated computational chemistry workflow (for drug development) in collaboration with AstraZeneca, NVIDIA, and AWS.

Latest IonQ (IONQ) Stock News and Developments

Conclusion

Quantum technology is widely expected to revolutionize industries by solving complex problems. The record-breaking experiment at Caltech demonstrates that large-scale, error-corrected quantum computing may be getting closer to reality.

With such research, along with new architectures, advances in materials, and commercial players accelerating development, quantum technology could become a universally deployable tool in the coming years, enabling breakthroughs in science and society.

Click here for a list of top quantum computing companies.

References

1. Grün, D. S., White, S. J. M., Ortu, A., Di Carli, A., Edri, H., Lepers, M., Mark, M. J. & Ferlaino, F. (2024). Optical Tweezer Arrays of Erbium Atoms. Physical Review Letters, 133, 223402. Published 26 November 2024. https://doi.org/10.1103/PhysRevLett.133.223402
2. Neven, H. (2024, December 9). Meet Willow, our state-of-the-art quantum chip. Google Research Blog. Retrieved from https://blog.google/technology/research/google-willow-quantum-chip/
3. Manetsch, H. J., Nomura, G., Bataille, E., et al. (2025). A tweezer array with 6100 highly coherent atomic qubits. Nature. Published 24 September 2025. https://doi.org/10.1038/s41586-025-09641-4
4. Manetsch, H. J., Nomura, G., Bataille, E., Leung, K. H., Lv, X. & Endres, M. (2025). A tweezer array with 6100 highly coherent atomic qubits. Nature. (Version of Record), published 24 September 2025. https://doi.org/10.1038/s41586-025-09641-4
5. Putterman, H., Noh, K., Hann, C. T., et al. (2025). Hardware-efficient quantum error correction via concatenated bosonic qubits. Nature, 638, 927–934. (Version of Record), published 26 February 2025. https://doi.org/10.1038/s41586-025-08642-7