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Ultrafast and high resolution spatial light modulation for cold atoms
Authors:
Alexander Dennisovich Deters,
Yanfei Li,
Alexander Douglas,
Markus Greiner,
Aaron W. Young
Abstract:
Programmable arrays of ultracold atoms are a leading platform for quantum computation and simulation, enabling state-of-the-art implementations of quantum error correction, and analog simulations of Hubbard models that address open problems in condensed matter physics. In these systems, all local control is mediated through precisely shaped optical fields, and so the challenge of managing many-bod…
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Programmable arrays of ultracold atoms are a leading platform for quantum computation and simulation, enabling state-of-the-art implementations of quantum error correction, and analog simulations of Hubbard models that address open problems in condensed matter physics. In these systems, all local control is mediated through precisely shaped optical fields, and so the challenge of managing many-body quantum states becomes an exercise in optical design. In particular, one wishes for fast, flexible control with low disorder and heating, and access to large arrays with many atoms. An ideal optical system therefore must generate arbitrary patterns with high spatial resolution and low disorder, and alter these patterns on a timescale that is faster than the relevant atomic dynamics. Here, we present an optical system that is comparable to previous approaches in scale, while advancing all other axes. We demonstrate arbitrary pattern generation with $10^{-3}$ intensity resolution, a frame rate of $>84$ MFPS (megaframes per second), and a spatial resolution of $83 \times 52$ beam waists (with $11 \times 52$ waists accessible via a single $40$ GHz electro-optic modulator). These capabilities unlock a new class of experiments. We develop and numerically validate a scheme for fully programmable Hubbard models, with time-dependent control over local chemical potentials, tunneling amplitudes, on-site interactions, and patterns of artificial magnetic flux. The same architecture performs fast, arbitrary permutations of tweezers in 2D, decoupling optical constraints from the design of high-rate error-correcting codes.
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Submitted 18 August, 2026;
originally announced August 2026.
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Assembling a Bose-Hubbard superfluid from tweezer-controlled single atoms
Authors:
William J. Eckner,
Theodor Lukin Yelin,
Alec Cao,
Aaron W. Young,
Nelson Darkwah Oppong,
Lode Pollet,
Adam M. Kaufman
Abstract:
Quantum simulation relies on the preparation and control of low-entropy many-body systems to reveal the behavior of classically intractable models. The development of new approaches for realizing such systems therefore represents a frontier in quantum science. Here we experimentally demonstrate a new protocol for generating ultracold, itinerant many-body states in a tunnel-coupled two-dimensional…
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Quantum simulation relies on the preparation and control of low-entropy many-body systems to reveal the behavior of classically intractable models. The development of new approaches for realizing such systems therefore represents a frontier in quantum science. Here we experimentally demonstrate a new protocol for generating ultracold, itinerant many-body states in a tunnel-coupled two-dimensional optical lattice. We do this by adiabatically connecting a near-ground-state-cooled array of up to 50 single strontium-86 atoms with a Bose-Hubbard superfluid. Through comparison with finite-temperature quantum-Monte-Carlo calculations, we estimate that the entropy per particle of the prepared many-body states is approximately $2 k_B$, and that the achieved temperatures are consistent with a significant superfluid fraction. This represents the first time that itinerant many-body systems have been prepared from rearranged atoms, opening the door to bottom-up assembly of a wide range of neutral-atom and molecular systems.
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Submitted 30 December, 2025;
originally announced December 2025.
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Pseudogap in a Fermi-Hubbard quantum simulator
Authors:
Lev Haldar Kendrick,
Anant Kale,
Youqi Gang,
Alexander Dennisovich Deters,
Martin Lebrat,
Aaron W. Young,
Markus Greiner
Abstract:
Understanding doped Mott insulators is a fundamental goal in condensed matter physics, with relevance to cuprate superconductors and other quantum materials. The doped Hubbard model minimally describes such systems, and has explicated some of their complex behavior. However, many open questions remain concerning the anomalous metallic states which emerge at low temperatures and intermediate doping…
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Understanding doped Mott insulators is a fundamental goal in condensed matter physics, with relevance to cuprate superconductors and other quantum materials. The doped Hubbard model minimally describes such systems, and has explicated some of their complex behavior. However, many open questions remain concerning the anomalous metallic states which emerge at low temperatures and intermediate doping and which, in cuprates, give rise to high-temperature superconductivity upon cooling. Here we observe a crossover between a normal metal and a pseudogapped metal in the Hubbard model by performing thermodynamic and spectroscopic measurements in a cold atom quantum simulator, leveraging a recent several-fold reduction in experimentally achievable temperatures. Measurements of the compressibility show a maximum versus doping that develops upon cooling, signaling an inflection point in the equation of state. We track this maximum versus interaction strength, revealing a line of thermodynamic anomalies in the phase diagram that separates an underdoped from an overdoped metal at large interactions. Lattice modulation spectroscopy shows a loss of spectral weight at low energies in the underdoped regime which is non-uniform in the Brillouin zone, indicating the formation of a pseudogap. We use this signal to establish a pseudogap phase diagram as a function of interactions and doping. Our results experimentally demonstrate the existence of a pseudogapped metal in the Hubbard model, partially characterize the pseudogap regime, and suggest a link between the pseudogap and charge order which can be probed in future work. Furthermore, this work demonstrates the utility of quantum simulation in addressing frontier problems in correlated electron physics.
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Submitted 22 September, 2025;
originally announced September 2025.
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Multi-qubit gates and Schrödinger cat states in an optical clock
Authors:
Alec Cao,
William J. Eckner,
Theodor Lukin Yelin,
Aaron W. Young,
Sven Jandura,
Lingfeng Yan,
Kyungtae Kim,
Guido Pupillo,
Jun Ye,
Nelson Darkwah Oppong,
Adam M. Kaufman
Abstract:
Many-particle entanglement is a key resource for achieving the fundamental precision limits of a quantum sensor. Optical atomic clocks, the current state-of-the-art in frequency precision, are a rapidly emerging area of focus for entanglement-enhanced metrology. Augmenting tweezer-based clocks featuring microscopic control and detection with the high-fidelity entangling gates developed for atom-ar…
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Many-particle entanglement is a key resource for achieving the fundamental precision limits of a quantum sensor. Optical atomic clocks, the current state-of-the-art in frequency precision, are a rapidly emerging area of focus for entanglement-enhanced metrology. Augmenting tweezer-based clocks featuring microscopic control and detection with the high-fidelity entangling gates developed for atom-array information processing offers a promising route towards leveraging highly entangled quantum states for improved optical clocks. Here we develop and employ a family of multi-qubit Rydberg gates to generate Schrödinger cat states of the Greenberger-Horne-Zeilinger (GHZ) type with up to 9 optical clock qubits in a programmable atom array. In an atom-laser comparison at sufficiently short dark times, we demonstrate a fractional frequency instability below the standard quantum limit using GHZ states of up to 4 qubits. However, due to their reduced dynamic range, GHZ states of a single size fail to improve the achievable clock precision at the optimal dark time compared to unentangled atoms. Towards overcoming this hurdle, we simultaneously prepare a cascade of varying-size GHZ states to perform unambiguous phase estimation over an extended interval. These results demonstrate key building blocks for approaching Heisenberg-limited scaling of optical atomic clock precision.
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Submitted 13 October, 2024; v1 submitted 25 February, 2024;
originally announced February 2024.
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An atomic boson sampler
Authors:
Aaron W. Young,
Shawn Geller,
William J. Eckner,
Nathan Schine,
Scott Glancy,
Emanuel Knill,
Adam M. Kaufman
Abstract:
A boson sampler implements a restricted model of quantum computing. It is defined by the ability to sample from the distribution resulting from the interference of identical bosons propagating according to programmable, non-interacting dynamics. Here, we demonstrate a new combination of tools for implementing boson sampling using ultracold atoms in a two-dimensional, tunnel-coupled optical lattice…
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A boson sampler implements a restricted model of quantum computing. It is defined by the ability to sample from the distribution resulting from the interference of identical bosons propagating according to programmable, non-interacting dynamics. Here, we demonstrate a new combination of tools for implementing boson sampling using ultracold atoms in a two-dimensional, tunnel-coupled optical lattice. These tools include fast and programmable preparation of large ensembles of nearly identical bosonic atoms ($99.5^{+0.5}_{-1.6}\;\%$ indistinguishability) by means of rearrangement with optical tweezers and high-fidelity optical cooling, propagation for variable evolution time in the lattice with low loss ($5.0(2)\;\%$, independent of evolution time), and high fidelity detection of the atom positions after their evolution (typically $99.8(1)\;\%$). With this system, we study specific instances of boson sampling involving up to $180$ atoms distributed among $\sim 1000$ sites in the lattice. Direct verification of a given boson sampling distribution is not feasible in this regime. Instead, we introduce and perform targeted tests to determine the indistinguishability of the prepared atoms, to characterize the applied family of single particle unitaries, and to observe expected bunching features due to interference for a large range of atom numbers. When extended to interacting systems, our work demonstrates the core capabilities required to directly assemble ground and excited states in simulations of various Hubbard models.
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Submitted 8 July, 2024; v1 submitted 13 July, 2023;
originally announced July 2023.
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Realizing spin squeezing with Rydberg interactions in a programmable optical clock
Authors:
William J. Eckner,
Nelson Darkwah Oppong,
Alec Cao,
Aaron W. Young,
William R. Milner,
John M. Robinson,
Jun Ye,
Adam M. Kaufman
Abstract:
Neutral-atom arrays trapped in optical potentials are a powerful platform for studying quantum physics, combining precise single-particle control and detection with a range of tunable entangling interactions. For example, these capabilities have been leveraged for state-of-the-art frequency metrology as well as microscopic studies of entangled many-particle states. In this work, we combine these a…
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Neutral-atom arrays trapped in optical potentials are a powerful platform for studying quantum physics, combining precise single-particle control and detection with a range of tunable entangling interactions. For example, these capabilities have been leveraged for state-of-the-art frequency metrology as well as microscopic studies of entangled many-particle states. In this work, we combine these applications to realize spin squeezing - a widely studied operation for producing metrologically useful entanglement - in an optical atomic clock based on a programmable array of interacting optical qubits. In this first demonstration of Rydberg-mediated squeezing with a neutral-atom optical clock, we generate states that have almost 4 dB of metrological gain. Additionally, we perform a synchronous frequency comparison between independent squeezed states and observe a fractional frequency stability of $1.087(1)\times 10^{-15}$ at one-second averaging time, which is 1.94(1) dB below the standard quantum limit, and reaches a fractional precision at the $10^{-17}$ level during a half-hour measurement. We further leverage the programmable control afforded by optical tweezer arrays to apply local phase shifts in order to explore spin squeezing in measurements that operate beyond the relative coherence time with the optical local oscillator. The realization of this spin-squeezing protocol in a programmable atom-array clock opens the door to a wide range of quantum-information inspired techniques for optimal phase estimation and Heisenberg-limited optical atomic clocks.
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Submitted 23 July, 2023; v1 submitted 14 March, 2023;
originally announced March 2023.
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Tweezer-programmable 2D quantum walks in a Hubbard-regime lattice
Authors:
Aaron W. Young,
William J. Eckner,
Nathan Schine,
Andrew M. Childs,
Adam M. Kaufman
Abstract:
Quantum walks provide a framework for understanding and designing quantum algorithms that is both intuitive and universal. To leverage the computational power of these walks, it is important to be able to programmably modify the graph a walker traverses while maintaining coherence. Here, we do this by combining the fast, programmable control provided by optical tweezer arrays with the scalable, ho…
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Quantum walks provide a framework for understanding and designing quantum algorithms that is both intuitive and universal. To leverage the computational power of these walks, it is important to be able to programmably modify the graph a walker traverses while maintaining coherence. Here, we do this by combining the fast, programmable control provided by optical tweezer arrays with the scalable, homogeneous environment of an optical lattice. Using this new combination of tools we study continuous-time quantum walks of single atoms on a 2D square lattice, and perform proof-of-principle demonstrations of spatial search using these walks. When scaled to more particles, the capabilities demonstrated here can be extended to study a variety of problems in quantum information science and quantum simulation, including the deterministic assembly of ground and excited states in Hubbard models with tunable interactions, and performing versions of spatial search in a larger graph with increased connectivity, where search by quantum walk can be more effective.
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Submitted 2 February, 2022;
originally announced February 2022.
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Long-lived Bell states in an array of optical clock qubits
Authors:
Nathan Schine,
Aaron W. Young,
William J. Eckner,
Michael J. Martin,
Adam M. Kaufman
Abstract:
The generation of long-lived entanglement on an optical clock transition is a key requirement to unlocking the promise of quantum metrology. Arrays of neutral atoms constitute a capable quantum platform for accessing such physics, where Rydberg-based interactions may generate entanglement between individually controlled and resolved atoms. To this end, we leverage the programmable state preparatio…
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The generation of long-lived entanglement on an optical clock transition is a key requirement to unlocking the promise of quantum metrology. Arrays of neutral atoms constitute a capable quantum platform for accessing such physics, where Rydberg-based interactions may generate entanglement between individually controlled and resolved atoms. To this end, we leverage the programmable state preparation afforded by optical tweezers along with the efficient strong confinement of a 3d optical lattice to prepare an ensemble of strontium atom pairs in their motional ground state. We engineer global single-qubit gates on the optical clock transition and two-qubit entangling gates via adiabatic Rydberg dressing, enabling the generation of Bell states, $|ψ\rangle = \frac{1}{\sqrt{2}}\left(|gg\rangle + i|ee\rangle \right)$, with a fidelity of $\mathcal{F}= 92.8(2.0)$%. For use in quantum metrology, it is furthermore critical that the resulting entanglement be long lived; we find that the coherence of the Bell state has a lifetime of $τ_{bc} = 4.2(6)$ s via parity correlations and simultaneous comparisons between entangled and unentangled ensembles. Such Bell states can be useful for enhancing metrological stability and bandwidth. Further rearrangement of hundreds of atoms into arbitrary configurations using optical tweezers will enable implementation of many-qubit gates and cluster state generation, as well as explorations of the transverse field Ising model and Hubbard models with entangled or finite-range-interacting tunnellers.
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Submitted 29 November, 2021;
originally announced November 2021.
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High-Power, Fiber-Laser-Based Source for Magic-Wavelength Trapping in Neutral-Atom Optical Clocks
Authors:
William J. Eckner,
Aaron W. Young,
Nathan Schine,
Adam M. Kaufman
Abstract:
We present a continuous-wave, 810 nm laser with watt-level powers. Our system is based on difference-frequency generation of 532 nm and 1550 nm fiber lasers in a single pass through periodically poled lithium niobate (PPLN). We measure the broadband spectral noise and residual intensity noise to be compatible with off-resonant dipole trapping of ultracold atoms. Given the large bandwidth of the fi…
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We present a continuous-wave, 810 nm laser with watt-level powers. Our system is based on difference-frequency generation of 532 nm and 1550 nm fiber lasers in a single pass through periodically poled lithium niobate (PPLN). We measure the broadband spectral noise and residual intensity noise to be compatible with off-resonant dipole trapping of ultracold atoms. Given the large bandwidth of the fiber amplifiers, the output can be optimized for a range of wavelengths, including the strontium clock-magic wavelength of 813 nm. Furthermore, with the exploration of more appropriate nonlinear crystals, we believe there is a path toward scaling this proof-of-principle design to many watts of power, and that this approach could provide a robust, rack-mountable trapping-laser for future use in strontium-based optical clocks.
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Submitted 22 May, 2021;
originally announced May 2021.
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A tweezer clock with half-minute atomic coherence at optical frequencies and high relative stability
Authors:
Aaron W. Young,
William J. Eckner,
William R. Milner,
Dhruv Kedar,
Matthew A. Norcia,
Eric Oelker,
Nathan Schine,
Jun Ye,
Adam M. Kaufman
Abstract:
The preparation of large, low-entropy, highly coherent ensembles of identical quantum systems is foundational for many studies in quantum metrology, simulation, and information. Here, we realize these features by leveraging the favorable properties of tweezer-trapped alkaline-earth atoms while introducing a new, hybrid approach to tailoring optical potentials that balances scalability, high-fideli…
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The preparation of large, low-entropy, highly coherent ensembles of identical quantum systems is foundational for many studies in quantum metrology, simulation, and information. Here, we realize these features by leveraging the favorable properties of tweezer-trapped alkaline-earth atoms while introducing a new, hybrid approach to tailoring optical potentials that balances scalability, high-fidelity state preparation, site-resolved readout, and preservation of atomic coherence. With this approach, we achieve trapping and optical clock excited-state lifetimes exceeding $ 40 $ seconds in ensembles of approximately $ 150 $ atoms. This leads to half-minute-scale atomic coherence on an optical clock transition, corresponding to quality factors well in excess of $10^{16}$. These coherence times and atom numbers reduce the effect of quantum projection noise to a level that is on par with leading atomic systems, yielding a relative fractional frequency stability of $5.2(3)\times10^{-17}~(τ/s)^{-1/2}$ for synchronous clock comparisons between sub-ensembles within the tweezer array. When further combined with the microscopic control and readout available in this system, these results pave the way towards long-lived engineered entanglement on an optical clock transition in tailored atom arrays.
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Submitted 23 June, 2020; v1 submitted 13 April, 2020;
originally announced April 2020.
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Seconds-scale coherence in a tweezer-array optical clock
Authors:
Matthew A. Norcia,
Aaron W. Young,
William J. Eckner,
Eric Oelker,
Jun Ye,
Adam M. Kaufman
Abstract:
Optical clocks based on atoms and ions achieve exceptional precision and accuracy, with applications to relativistic geodesy, tests of relativity, and searches for dark matter. Achieving such performance requires balancing competing desirable features, including a high particle number, isolation of atoms from collisions, insensitivity to motional effects, and high duty-cycle operation. Here we dem…
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Optical clocks based on atoms and ions achieve exceptional precision and accuracy, with applications to relativistic geodesy, tests of relativity, and searches for dark matter. Achieving such performance requires balancing competing desirable features, including a high particle number, isolation of atoms from collisions, insensitivity to motional effects, and high duty-cycle operation. Here we demonstrate a new platform based on arrays of ultracold strontium atoms confined within optical tweezers that realizes a novel combination of these features by providing a scalable platform for isolated atoms that can be interrogated multiple times. With this tweezer-array clock, we achieve greater than 3 second coherence times and record duty cycles up to 96%, as well as stability commensurate with leading platforms. By using optical tweezer arrays --- a proven platform for the controlled creation of entanglement through microscopic control --- this work further promises a new path toward combining entanglement enhanced sensitivities with the most precise optical clock transitions.
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Submitted 24 July, 2019; v1 submitted 24 April, 2019;
originally announced April 2019.
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Microscopic control and detection of ultracold strontium in optical-tweezer arrays
Authors:
M. A. Norcia,
A. W. Young,
A. M. Kaufman
Abstract:
We demonstrate a set of tools for microscopic control of neutral strontium atoms. We report single-atom loading into an array of sub-wavelength scale optical tweezers, light-shift free control of a narrow-linewidth optical transition, three-dimensional ground-state cooling, and high-fidelity nondestructive imaging of single atoms on sub-wavelength spatial scales. Extending the microscopic control…
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We demonstrate a set of tools for microscopic control of neutral strontium atoms. We report single-atom loading into an array of sub-wavelength scale optical tweezers, light-shift free control of a narrow-linewidth optical transition, three-dimensional ground-state cooling, and high-fidelity nondestructive imaging of single atoms on sub-wavelength spatial scales. Extending the microscopic control currently achievable in single-valence-electron atoms to species with more complex internal structure, like strontium, unlocks a wealth of opportunities in quantum information science, including tweezer-based metrology, new quantum computing architectures, and new paths to low-entropy many-body physics.
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Submitted 15 October, 2018;
originally announced October 2018.