About the Kaufman Group | JILA - Exploring the Frontiers of Physics

Higher accuracy atomic clocks, such as the “tweezer clock” depicted here, could result from linking or “entangling” atoms in a new way through a method known as “spin squeezing,” in which one property of an atom is measured more precisely than is usually allowed in quantum mechanics by decreasing the precision in which a complementary property is measured.

New Spin-Squeezing Techniques Let Atoms Work Together for Better Quantum Measurements

Long-lived entangelement of Bell state pairs compared to single unentangled atoms in a 3D optical lattice. The Bell state "stopwatch" ticks twice as fast than that of a single atom, holding the promise of higher stability and higher bandwidth for optical clocks.

Seeing Quantum Weirdness: Superposition, Entanglement, and Tunneling

A rendering of a ytterbium qubit held within a set of optical tweezers

Tweezing a New Kind of Qubit

optical tweezers holding atoms, connected by a clock

Tweezing a New Kind of Atomic Clock

Figure of trapped and cooled single alkaline-earth atoms.

The Strontium Optical Tweezer

How does classical physics –- such as statistical mechanics — emerge from the collective behavior of quantum mechanical systems? Can we develop new tools for the manipulation of individual particles, such as complex atoms, ions or molecules, whose interactions and internal degrees of freedom establish new prospects for quantum science?

To answer questions like these, our group applies the tools of atomic, molecular, and optical physics to the microscopic study and control of quantum systems, for applications in quantum simulation, quantum information, and metrology. We marry the tools of quantum gas microscopy, optical tweezer technology, and high precision spectroscopy in order to gain single-particle control at fundamental length scales and very small energy scales.

Towards these goals, we trap single alkaline-earth atoms in optical tweezer arrays, a powerful and effective technology that we demonstrated in 2018 for the first time. Optical tweezers allow precise single-particle control, the engineering of different forms of atomic interactions, and high-fidelity atom-resolved readout. However, while previous work with optical tweezers had focused on alkali atoms, the 2018 work opened the door to tweezer-based control of atoms with two electrons in their valence shell -- although a tiny addition, this additional electron gives rise to the rich internal structure of alkaline-earth atoms, which underlies their applications in metrology, quantum simulation, and quantum information. In this lab, we apply the microscopic control capabilities emerging from the optical tweezer toolset to the quantum science directions that emerge from the use of alkaline-earth atoms.

Research Areas

Quantum Metrology with Tweezer Clocks
One of the scientific pursuits for which alkaline-earth atoms are most famous is optical atomic clocks. In atoms like Strontium and Ytterbium, there exists a long-lived optical transition known as the “clock transition”. Viewed as an oscillator, this transition has an intrinsic quality factor of in excess of 10¹⁷— that is, it can ring quadrillions of times before the oscillations die out. This means this oscillator can serve as an exceptional time-keeper, and, indeed, in the past decade, such optical atomic clocks have allowed some of the most precise measurements ever made by humans.

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Assembled Hubbard Systems of Alkaline-earth Atoms
Another appealing aspect of alkaline-earth atoms is the presence of a second relatively narrow transition — though not as narrow as the clock transition — that can be used for ground-state laser cooling. This is especially powerful when combined with the possibility of rearranging optical tweezers to prepare arbitrary atomic distributions with very low entropy in the atomic spatial distribution. So far, large-scale demonstrations of atomic rearrangement have been used for spin models, with atoms that might be relatively hot in their motional degrees of freedom. In this project, we seek to prepare arbitrary distributions of scalable arrays of ground-state atoms for large scale itinerant models.

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Quantum Simulation and Information with Ytterbium Tweezer Arrays
Unlike their bosonic counterpart, fermionic isotopes of alkaline-earth atoms benefit from having nuclear spin. This spin has been proposed for new many-body models, such as SU(N) physics, as well as the basis for new qubit architectures. In a new experiment, we seek to gain single-qubit-resolved control of arrays of Ytterbium-171 atoms, where quantum information is stored in the spin-1/2 nuclear spin of this isotope. We seek to engineer the resulting system to fully exploit the high two-qubit gate speeds possible with large Rydberg Rabi frequencies from the excited clock state.

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In the Spotlight

Heising-Simons Foundation Awards $3 Million for Informing Gravity Theory

February 27, 2024: JILA and the University of Colorado Boulder Lead Pioneering Quantum Gravity Research with Heising-Simons Foundation Grant

The Heising-Simons Foundation's Science program has announced a generous grant of $3 million over three years, aimed at bolstering theoretical and experimental research efforts to bridge the realms of Atomic, Molecular, and Optical (AMO) physics with quantum gravity theories. Among the recipients, a notable grant was awarded to a multi-investigator collaboration spearheaded by the University of Colorado Boulder (CU Boulder) and JILA, a joint institute of CU Boulder and the National Institute of Standards and Technology (NIST).

October 19, 2023: JILA Fellows Ana Maria Rey and Adam Kaufman Featured in IEEE Spectrum Article

JILA and NIST Fellow Ana Maria Rey and JILA Fellow and NIST Physicist Adam Kaufman have both been recently featured in an article for IEEE Spectrum. In a pair of Nature papers, Rey and Kaufman both demonstrated the phenomena of spin-squeezing to reduce noise in their quantum systems. "All objects that follow the rules of quantum physics can exist in multiple energy states at once, an effect known as superposition," explains the IEEE Spectrum article. "Spin squeezing reduces all those possible superposition states to just a few possibilities in some respects, while expanding them in others."

August 30, 2023: Our squeezing paper is published in nature!

Our paper reporting squeezing below the standard quantum limit in a programmable atom array has been published in nature! Congratulations to the team! Exciting to co-publish with the Browaeys/Yao and Roos/Rey teams too!

JILA Fellow and NIST Physicist Adam Kaufman at work in his lab

December 14, 2022: JILA Fellow and NIST Physicist Adam Kaufman is awarded a grant from the 2023 Young Investigator Research Program

JILA Fellow, NIST Physicist, and University of Colorado Physics professor Adam Kaufman has been awarded a grant as part of the 2023 Young Investigator Research Program, or YIP. YIP was launched by the Air Force Office of Scientific Research, or AFOSR, the basic research arm of the Air Force Research Laboratory. The AFOSR's mission is to support Air Force goals of control and maximum utilization of air, space, and cyberspace. To do this, AFSOR is awarding $25 million in grants to 58 scientists and engineers from 44 research institutions and businesses in 22 states in 2023.

JILA Address

We are located at JILA: A joint institute of NIST and the University of Colorado Boulder.

Map | JILA Phone: 303-492-7789 | Address: 440 UCB, Boulder, CO 80309