Adam Kaufman

Chameleon Atoms: JILA Researchers Demonstrate Versatile Atomic Qubits That Can Pass Around Information

Daniel Packman — Thu, 11 Jun 2026 19:06:04 +0000

Chameleon Atoms: JILA Researchers Demonstrate Versatile Atomic Qubits That Can Pass Around Information Daniel Packman Thu, 06/11/2026 - 13:06

Bailey Bedford / Freelance Science Communicator

Researchers are developing new technologies that harness quantum physics to defy the familiar constraints of daily life and established approaches. A variety of quantum simulations, quantum sensors and quantum computers have been developed that can significantly outperform existing technologies at certain tasks.

Many quantum technologies are built on a foundation of qubits—the structures that store quantum states in ways that are practical to manipulate and interpret. Researchers and engineers are exploring many different approaches to making and using qubits, spanning platforms like superconducting circuits, trapped ions, neutral atoms and more. The various approaches have different advantages and disadvantages that are being navigated as quantum technologies are developed.

In an article published June 11, 2026 in the journal Nature Physics, a team of JILA researchers led by JILA Fellow Adam Kaufman, in collaboration with researchers at the University of Innsbruck in Austria, report experiments demonstrating the versatility of ytterbium atoms as qubits. A neutral ytterbium atom is an adaptable chameleon that can be used as multiple styles of qubit, each bringing distinct advantages. Their experiments demonstrate a quantum multitool that can tackle quantum computations, quantum simulations and precise measurements of time and also combine the capabilities associated with each application.

The group focused on a specific isotope of ytterbium, ytterbium-171, that has appealing features for multiple quantum applications. Scientists can use laser light to cool ytterbium-171 atoms, to hold the atoms in ordered arrays and to alter their quantum states. The properties of the atoms let them function as qubits in multiple ways. At a basic level, a qubit requires a pair of distinguishable states that can exist in combinations of the states called superpositions. The group’s experiments used a method they developed to transfer quantum states between three distinct ways of making qubits.

“Ytterbium-171 has long been used for state-of-the-art optical clocks and recently has become a promising candidate for neutral-atom quantum computing,” says Kaufman. “Our work here demonstrates how these directions can be combined, as well as augmented with other directions in quantum information science, including quantum many-body dynamics.”

One qubit approach used in the experiment is built on states of ytterbium-171 atoms that have been harnessed in clocks that provide incredibly precise and reliable timekeeping. Researchers put the electrons of atoms in particular states that facilitate very precise measurements. The two distinct states of ytterbium-171 used in clocks can also be the basis of a qubit—called an optical qubit.

Ytterbium-171 also has a different electron state that scientists find useful. When researchers provide additional energy to an electron, they can put the atom in a state called a Rydberg state. The extra energy pushes the electron further from the center of the atom. Putting atoms into the Rydberg state, takes them from being essentially non-interacting to being strongly interacting, which helps scientists craft quantum simulations and generate entanglement—a uniquely quantum phenomenon of quantum states where the evolution and fates of quantum states are intrinsically connected. The Rydberg state combined with one of the states from the clock qubit can function as a Rydberg qubit.

Finally, the nucleus of the atom has an inherent quantum property called spin—it is like a tiny magnet that can either point with or against a magnetic field. The group used the two states of nuclear spin pointing in opposite directions as the basis of a qubit, called a nuclear qubit. The resulting nuclear qubits are a convenient and reliable way to perform quantum computing operations.

Since the nuclear qubit is based on the spin of the nucleus, the researchers were free to use atoms with the electrons in a particular state of their choice. This let the team choose atomic states so that all three of their qubit types shared one of the states of the atom.

The group developed a way to move entangled quantum states between these distinct qubit paradigms. The team took advantage of the fact that shining a light of a particular frequency (color) can predictably change the state of the atoms even when they are entangled.

Since all three types of qubits share one of their two defining states, the superposition of that half of a qubit can be flipped to either of the alternative qubits. Then, the remaining half left in the original qubit can be moved to complete the new qubit. Since each pair of states responds to a different frequency of light, the team can alternate beams to direct the qubits through the necessary shuffling act of transferring a state.

The researchers demonstrated that they could move multi-particle states between pairs of qubits in the different paradigms and then performed an experiment bridging the three qubit styles and their corresponding domains of usefulness. They created a quantum state of the Rydberg qubit using techniques from the realm of quantum simulation and then passed it to the nuclear qubit, where they performed a quantum computing operation to slightly adjust it. Finally, they passed that state onto the clock qubit, where it could potentially be used to perform measurements related to time and frequency. The procedure demonstrates how ytterbium atoms can be the foundation of a device with the flexibility to shift between simulation, computing and metrology.

“This can connect quantum simulation to quantum computing to quantum metrology in a single atomic species,” says JILA graduate student Aruku Senoo, who was the first author of the article. “Once you make that kind of system, if you develop some technique for quantum simulation, you can apply it for quantum computing, or if you develop some state generation mechanism for quantum computing, you can apply it for quantum metrology.”

The researchers also showed that they could transfer quantum states that extended over larger numbers of qubits. The researchers at the University of Innsbruck had theoretically developed a method to calculate the optimal way to make a particular quantum state called the Greenberger-Horne-Zeilinger (GHZ) states. The two groups worked together to identify the pulse of light needed for their experimental setup to create a GHZ state spread across as many of their qubits as they could manage. With the optimized light pulse, the team successfully made states with up to 20 Rydberg qubits at a time and then transferred them to nuclear qubits. The collaboration describes the theory behind this technique in an article published recently in the journal Physical Review Letters.

The extra steps to shuffle states around introduced more opportunities for errors to occur, but fortunately, the optical qubits provided a measurement method to circumvent many of the errors that popped up in their experiment. Using the optical qubits provided an improved method for the team to detect when tasks using Rydberg or nuclear qubits had produced an error where the atom was no longer in a valid state—for instance sometimes an atom will randomly release energy and leave the Rydberg state. Detecting one of these errors let the team throw out that measurement instead of proceeding with corrupted results.

They demonstrated that detecting such bad experimental runs could improve how reliably they made two qubits interact. Using the new technique and throwing out bad results, they achieved a two-qubit gate fidelity—a critical value used to judge a quantum computer—of 99.78% out of an ideal 100%.

“We show that we can do a very competitive two-qubit gate,” says JILA postdoctoral researcher Alexander Baumgärtner, who is an author of the paper. “It's one of the best neutral atom two-qubit gates that has been shown so far.”

The researchers say they hope that moving forward, their approach will allow the fields of quantum computing, simulation and metrology to intermix and share ideas. For instance, using quantum simulation and computing to generate useful states for quantum measurements.

“What we showed in the paper is just the beginning,” Senoo says. “What I'm excited about is pushing this forward.”

In an article published June 11, 2026 in the journal Nature Physics, a team of JILA researchers led by JILA Fellow Adam Kaufman, in collaboration with researchers at the University of Innsbruck in Austria, report experiments demonstrating the versatility of ytterbium atoms as qubits. A neutral ytterbium atom is an adaptable chameleon that can be used as multiple styles of qubit, each bringing distinct advantages. Their experiments demonstrate a quantum multitool that can tackle quantum computations, quantum simulations and precise measurements of time and also combine the capabilities associated with each application.

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Google Quantum AI Engages JILA Fellow Adam Kaufman to Lead New Neutral Atom Quantum Computing Effort

Steven Burrows — Tue, 24 Mar 2026 19:12:02 +0000

Google Quantum AI Engages JILA Fellow Adam Kaufman to Lead New Neutral Atom Quantum Computing Effort Steven Burrows Tue, 03/24/2026 - 13:12

Steven Burrows / JILA Science Communications Manager

Adam Kaufman (left) inspects an optical atomic clock at JILA on the University of Colorado campus with students Nelson Darkwah Oppong, Alec Cao and Theo Lukin Yelin. (Image Credit: Patrick Campbell, University of Colorado)

Today, Google Quantum AI announced a major expansion of its quantum computing research program, naming JILA Fellow Adam Kaufman to lead a newly formed neutral atom quantum hardware team. The initiative marks Google’s first large-scale investment in neutral atom quantum computing, a rapidly advancing platform that complements its long‑standing work in superconducting qubits.

Kaufman, an internationally recognized leader in neutral atom physics, will continue his research at JILA as a JILA Fellow while maintaining his academic appointment in the Department of Physics at the University of Colorado Boulder. According to The Colorado Sun, Kaufman’s dual role reflects Google’s strategy of closely integrating industrial-scale engineering with cutting-edge academic research, particularly in Boulder’s growing quantum ecosystem.

In announcing the program, Google emphasized that neutral atom quantum processors offer unique advantages, including the ability to scale to very large arrays—currently on the order of thousands to tens of thousands of qubits—with highly flexible, “any‑to‑any” connectivity. While neutral atom systems operate more slowly than superconducting circuits, their scalability in qubit number makes them especially promising for quantum simulation and fault‑tolerant architectures. Google views the parallel development of both platforms as a way to accelerate progress toward commercially useful quantum computers.

This new collaboration further strengthens JILA’s national and international leadership in quantum science, building on its major federally funded research centers and broad portfolio of competitive grants. By bridging foundational research and industrial-scale quantum engineering, the partnership underscores JILA’s central role in shaping the future of quantum technology.

Please join us in congratulating Adam Kaufman on this exciting opportunity and on his continued contributions to JILA, CU Boulder, and the global quantum research community.

Learn more:

The Colorado Sun: Google taps Boulder physicist to lead new quantum computing effort
Google Quantum AI Blog: Building superconducting and neutral atom quantum computers

Google Quantum AI has named JILA Fellow Adam Kaufman to lead a new neutral atom quantum computing hardware team, marking a major expansion of its quantum research program. Kaufman will continue his research at JILA and CU Boulder, strengthening JILA’s leadership and impact in national and international quantum science.

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High-fidelity gates and creation of entangled states in Yb171 nuclear-spin qubits

Steven Burrows — Sun, 22 Mar 2026 18:17:50 +0000

High-fidelity gates and creation of entangled states in Yb171 nuclear-spin qubits Steven Burrows Sun, 03/22/2026 - 12:17

Our paper on preparing entangled states in Yb171 has been accepted in Nature physics! Congratulations to the team! We show high-fidelity gates in the metastable qubit, high-fidelity three-outcome measurements, and coherent mapping of entangled states between the Rydberg, nuclear, and optical qubits. This work suggests several new directions, including in quantum error correction, hybrid digital-analog quantum simulations, and quantum metrology.

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New proposal for using quantum error correction in metrology

Steven Burrows — Sun, 22 Mar 2026 18:16:31 +0000

New proposal for using quantum error correction in metrology Steven Burrows Sun, 03/22/2026 - 12:16

In quantum metrology, it has been considered for some time whether quantum error correction can be used to enhance precision measurements. Here, the primary challenge is devising codes ad protocols that correct noise while not correcting the unknown signal being sensed. In this collaboration with the Pichler, we identify some promising conditions for leveraging quantum error correction for enhanced sensing, even when signal and noise couple identically to sensor qubits.

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Assembling a superfluid from individual atoms

Steven Burrows — Sun, 22 Mar 2026 18:14:16 +0000

Assembling a superfluid from individual atoms Steven Burrows Sun, 03/22/2026 - 12:14

Since it was first proposed in 2004 by David Weiss and Maxim Olshanii, it has been a goal to see whether atomic rearrangement and high-fidelity ground-state laser cooling could employed to prepare superfluids and low-entropy many-body states of itinerant matter. In this work, we demonstrate such a protocol, opening a new path to assembling ground-state many-body state of bosonic and fermionic quantum systems.

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JILA Joins DOE’s Quantum Systems Accelerator for Next Phase of Quantum Innovation

Steven Burrows — Tue, 04 Nov 2025 19:18:36 +0000

JILA Joins DOE’s Quantum Systems Accelerator for Next Phase of Quantum Innovation Steven Burrows Tue, 11/04/2025 - 12:18

Steven Burrows / JILA Science Communications Manager

A round glass cell (centre, in black frame) is designed to hold a gas of molecules cooled to 50 billionths of a Kelvin. Credit: Ye Group/Steven Burrows/JILA

The U.S. Department of Energy (DOE) has announced a $625 million investment to advance the next phase of the National Quantum Information Science Research Centers, a cornerstone of the National Quantum Initiative. This funding will support five centers dedicated to accelerating quantum technologies that promise transformative impacts on science, industry, and national security.

Among these centers, the Quantum Systems Accelerator (QSA)—led by Lawrence Berkeley National Laboratory—will continue its mission to develop practical quantum systems that can solve real-world problems. QSA brings together leading institutions to tackle challenges in quantum computing, sensing, and networking, aiming to bridge the gap between theoretical advances and deployable technologies.

JILA is proud to remain a key partner in QSA through the Q-SEnSE Institute, which focuses on quantum sensing and precision measurement. These capabilities are essential for applications ranging from navigation and timing to probing fundamental physics. JILA Fellow Jun Ye will lead the JILA effort, supported by senior investigators and JILA Fellows Cindy Regal, Adam Kaufman, Ana Maria Rey, James Thompson, Murray Holland, and Xun Gao—a team internationally recognized for pioneering work in quantum optics, atomic physics, and many-body systems.

“JILA is proud to remain a key partner in QSA. Through our work in both QSA and Q-SEnSE, JILA plays a leading role in advancing quantum innovations at the national and international levels,” remarked Inese Berzina-Pitcher, Executive Director for Q-SEnSE.

The next five years of QSA will focus on building scalable quantum platforms, advancing error correction, and integrating quantum devices into scientific workflows. JILA’s expertise in ultracold atoms, optical lattices, and quantum simulation will play a critical role in these goals.

For more details, read the official announcements:

Energy Department Announces $625 Million to Advance the Next Phase of National Quantum Information Science Research Centers

The Quantum Systems Accelerator Embarks on Next Five Years of Pioneering Quantum Technologies for Science

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Cryogenic optical tweezer array

Steven Burrows — Wed, 28 May 2025 19:39:20 +0000

Cryogenic optical tweezer array Steven Burrows Wed, 05/28/2025 - 13:39

Our work on high optical access cryogenic system for Rydberg atoms has been published in PRX Quantum - see this viewpoint on our studies.

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Enhanced Rydberg dressing paper published!

Steven Burrows — Sun, 27 Apr 2025 17:32:36 +0000

Enhanced Rydberg dressing paper published! Steven Burrows Sun, 04/27/2025 - 11:32

We used features of alkaline-earth atoms to enhance the timescale coherent many-body physics using Rydberg-dressing, which enables studies of quantum magnetism and the creation of metrologically-useful entanglement. See the paper here.

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JILA Fellow and NIST Physicist and CU Boulder Physics Professor Adam Kaufman Honored with Prestigious PECASE Award

Steven Burrows — Tue, 14 Jan 2025 17:26:52 +0000

JILA Fellow and NIST Physicist and CU Boulder Physics Professor Adam Kaufman Honored with Prestigious PECASE Award Steven Burrows Tue, 01/14/2025 - 10:26

Kenna Hughes-Castleberry / JILA Science Communicator

JILA Fellow and NIST Physicist and CU Boulder Physics professor Adam Kaufman. Image credit: Kenna Hughes-Castleberry / JILA

JILA Fellow, National Institute of Standards and Technology (NIST) Physicist and University of Colorado Boulder physics professor Dr. Adam Kaufman has been awarded the prestigious Presidential Early Career Award for Scientists and Engineers (PECASE). President Joe Biden announced that this accolade represents the highest honor conferred by the U.S. government to early-career scientists and engineers who exhibit extraordinary potential and leadership in their respective fields. Kaufman’s groundbreaking contributions to quantum science have cemented his place among nearly 400 recipients recognized for their innovative research and commitment to advancing scientific frontiers.

“I feel very honored to receive the PECASE in recognition of my group’s work over the past several years,” Kaufman says. “I am also very appreciative of the unique environment at JILA, from administrative to shop support, that enables so much of our research.”

Established by President Clinton in 1996, the PECASE award celebrates early-career professionals whose work bridges the gap between cutting-edge research and societal impact. This year’s awardees, supported by 14 federal agencies, represent the vanguard of scientific and technological progress, tackling challenges in diverse fields such as agriculture, defense, healthcare, energy, and space exploration.

President Biden emphasized the critical role of science and technology in shaping a brighter future, citing legislative initiatives like the Bipartisan Infrastructure Law and the CHIPS and Science Act as testaments to the Administration’s commitment to bolstering research and development.

Kaufman’s pioneering work addresses fundamental questions about quantum systems and their interplay with classical physics. His research focuses on developing tools to manipulate individual particles—such as complex atoms, ions, or molecules—whose interactions and internal dynamics open new horizons for quantum simulation, quantum information, and precision metrology.

Kaufman's lab has achieved unprecedented single-particle control at microscopic scales by combining optical tweezer technology with high-precision spectroscopy and quantum gas microscopy. His groundbreaking 2018 demonstration of trapping single alkaline-earth atoms in optical tweezer arrays has since paved the way for transformative advances in quantum science.

“Dr. Kaufman is a pioneer in the science of optical-tweezer arrays, in which he holds and precisely manipulates individual atoms with beams of light,” states Dr. Andrew Wilson, Acting Director of the NIST Physical Measurement Laboratory (PML). “The major contributions that he and his team are making within NIST and JILA are advancing the goals of the U.S. National Quantum Initiative and are being used in a great many applications, ranging from fundamental science to commercial product development. This honor is a wonderful recognition for his outstanding scientific achievements.”

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JILA Fellow and NIST Physicist Adam Kaufman Combines Multiple Atomic Clocks into One System

Steven Burrows — Wed, 09 Oct 2024 19:23:55 +0000

JILA Fellow and NIST Physicist Adam Kaufman Combines Multiple Atomic Clocks into One System Steven Burrows Wed, 10/09/2024 - 13:23

Daniel Strain / CU Boulder Strategic Communications

JILA Fellow and NIST (National Institute of Standards and Technology) Physicist and University of Colorado Boulder Physics professor Adam Kaufman and his team have ventured into the minuscule realms of atoms and electrons. Their research involves creating an advanced optical atomic clock using a lattice of strontium atoms, enhanced by quantum entanglement—a phenomenon that binds the fate of particles together. This ambitious project could revolutionize timekeeping, potentially surpassing the "standard quantum limit" of precision.

In collaboration with JILA and NIST Fellow Jun Ye, the team highlighted their findings in Nature, demonstrating how their clock, operating under certain conditions, could exceed conventional accuracy benchmarks. Their work advances timekeeping and opens doors to new quantum technologies, such as precise environmental sensors.

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