Building up an optical clock Arrays of optical tweezers can be used to trap atoms, which can then be manipulated individually. Such arrays have shown promise in quantum simulation of many-body systems. Norcia et al. now demonstrate that they can also be used as a platform for optical clocks. The researchers lined up 10 optical tweezers in a one-dimensional array, where each tweezer held either one or zero atoms of strontium. The atoms were subjected to laser light whose frequency was tuned to a clock transition in strontium. By monitoring the number of atoms in each tweezer, the researchers measured a long coherence time of a few seconds. Increasing the number of tweezers should improve the figures of merit of this platform. Science , this issue p. 93
Building up an optical clock Arrays of optical tweezers can be used to trap atoms, which can then be manipulated individually. Such arrays have shown promise in quantum simulation of many-body systems. Norcia et al. now demonstrate that they can also be used as a platform for optical clocks. The researchers lined up 10 optical tweezers in a one-dimensional array, where each tweezer held either one or zero atoms of strontium. The atoms were subjected to laser light whose frequency was tuned to a clock transition in strontium. By monitoring the number of atoms in each tweezer, the researchers measured a long coherence time of a few seconds. Increasing the number of tweezers should improve the figures of merit of this platform. Science , this issue p. 93
Atomic Physics
Arrays of optical tweezers can be used to trap atoms, which can then be manipulated individually. Such arrays have shown promise in quantum simulation of many-body systems. Norcia et al. now demonstrate that they can also be used as a platform for optical clocks. The researchers lined up 10 optical tweezers in a one-dimensional array, where each tweezer held either one or zero atoms of strontium. The atoms were subjected to laser light whose frequency was tuned to a clock transition in strontium. By monitoring the number of atoms in each tweezer, the researchers measured a long coherence time of a few seconds. Increasing the number of tweezers should improve the figures of merit of this platform.
Science , this issue p. [93][1]
[1]: /lookup/doi/10.1126/science.aay0644
Optical tweezer arrays of neutral atoms have emerged as a versatile and powerful platform for quantum simulation and quantum information processing. In this thesis, I present the realization of an experimental platform for quantum simulation based on individually trapped strontium atoms in optical tweezer arrays. The experiment combines precise laser cooling, optical control, and high-resolution imaging to enable the manipulation and high fidelity detection of single atoms. I developed and optimized a two-stage three-dimensional magneto-optical trap (3D-MOT) that produces cold and dense samples of strontium atoms from a thermal beam. In the f irst stage, atoms are captured and precooled using the dipole-allowed 1S0 → 1P1 transition at 461nm (which has a linewidth of !=2ω ↑ 32MHz). The second stage employs the 1S0 → 3P1 narrow intercombination transition at 689nm (with a linewidth of !=2ω ↑7.5kHz) to further cool and compress the atomic cloud. By optimizing the trapping parameters, I achieved clouds with temperatures around 5μK and densities above 1010cm→3, providing ideal initial conditions for e!cient loading into optical tweezers. A 3↑3 array of 360μK deep optical tweezers is generated by spatially modulating an 813.4nm laser beam using two crossed acousto-optic deflectors. The deflected beams are relayed and focused into the science chamber using a high–numericalaperture objective, which simultaneously serves as the collection optics for atomic f luorescence. The fluorescence light emitted by the atoms is imaged onto a scientific qCMOS camera, enabling site-resolved detection of individual atoms. I implemented and optimized the in-trap cooling dynamics to prevent atom loss during imaging and to minimize residual thermal motion. In addition, by precisely tuning lightassisted collisions, multiple atoms occupancies are removed from the traps and a single-atom regime is reached in the array, with a filling fraction of about 50%. I have demonstrated a single-atom detection fidelity of 99,986(1)% and a survival probability of 97(2)% between subsequent image acquisition, comparable to other current state-of-the-art experiments. To characterize the platform, I carried out release-and-recapture experiments, from which it is possible to measure a temperature for the individually trapped atoms of 12.95(5)μK. These results demonstrate the successful implementation of a robust and high-fidelity platform for optical trapping and imaging of single strontium atoms. The apparatus provides the foundation for future quantum simulation experiments with alkalineearth atoms excited to the Rydberg state, o"ering precise control over individual particles and the ability to scale towards larger, programmable atomic arrays.
Optical tweezer arrays trapping ultracold atoms and molecules are a versatile quantum science platform with broad impact in quantum simulation, quantum computation, and quantum metrology. The polarization dependence of anisotropic vector and tensor light shifts offers a degree of freedom for precise quantum state engineering of trapped particles. Similarly, state-selective operations depend on the polarization of the addressing light through the atom--light coupling strength. Yet, methods for controlling the polarization of individual tweezers or local addressing beams remain an experimental challenge. Here, we demonstrate independent, site-resolved linear polarization rotation across an optical tweezer array by exploiting the local birefringence tunability of a spatial light modulator. Applying this capability to an array of 88Sr atoms, we homogenize differential light shifts imparted by the 813-nm tweezers to the narrow 1S0↔3P1 transition, enabling sideband cooling under a magic-angle condition. Furthermore, we show dynamic transport of trapped atoms across distinct polarization zones with high survival and preserved coherence. Finally, we characterize tweezer polarization noise and demonstrate closed-loop stabilization referenced to the atomic transition frequency, reaching mrad-level stability. Our work establishes a technique for manipulating polarization-sensitive atomic and molecular transitions in tweezer architectures, with immediate applications to optical tweezer clocks and multi-zone quantum processors.
Tweezing cold molecules Arrays of optical tweezers have been used to trap atoms, but trapping and laser-cooling molecules in this setting is tricky. Such an approach would, however, be generalizable to many molecular species. Anderegg et al. created an optical tweezer array of calcium monofluoride molecules, which were laser cooled to their ground state (see the Perspective by Kotochigova). By distinguishing between single and multiple molecules in the tweezers, the researchers were able to observe molecular collisions. Boasting exquisite control over individual molecules, the optical tweezer array platform holds much promise for extending the applications of ultracold molecules. Science , this issue p. 1156 ; see also p. 1079
Optical tweezer arrays 1,2 have transformed atomic and molecular physics, now forming the backbone for a range of leading experiments in quantum computing 3–8 , simulation 1,9–12 , and metrology 13–15 . Typical experiments trap tens to hundreds of atomic qubits, and recently systems with around one thousand atoms were realized without defining qubits or demonstrating coherent control 16–18 . However, scaling to thousands of atomic qubits with long coherence times, low-loss, and high-fidelity imaging is an outstanding challenge and critical for progress in quantum science, particularly towards quantum error correction 19,20 . Here, we experimentally realize an array of optical tweezers trapping over 6,100 neutral atoms in around 12,000 sites, simultaneously surpassing state-of-the-art performance for several metrics that underpin the success of the platform. Specifically, while scaling to such a large number of atoms, we demonstrate a coherence time of 12.6(1) seconds, a record for hyperfine qubits in an optical tweezer array. We show room-temperature trapping lifetimes of ~ 23 minutes, enabling record-high imaging survival of 99.98952(1)% with an imaging fidelity of over 99.99%. We present a plan for zone-based quantum computing 5,21 and demonstrate necessary coherence-preserving qubit transport and pick-up/drop-off operations on large spatial scales, characterized through interleaved randomized benchmarking. Our results, along with recent developments 8,22–24 , indicate that universal quantum computing and quantum error correction with thousands to tens of thousands of physical qubits could be a near-term prospect.
Alkaline Atoms Held with Optical TweezersThree separate groups demonstrate the trapping of two-electron atoms in arrays of optical tweezers, opening up new opportunities for quantum simulation and many-body studies.by Antoine Browaeys * Q uantum technology is a very active field of research, in which the resources of quantum physics, such as superposition and entanglement, are utilized to perform tasks that are classically hard or impossible.The promises from this field are many, ranging from quantum computation of difficult mathematical problems to the building of more sensitive sensors.But to realize these possibilities, experimentalists have to engineer well-controlled quantum systems made of many individual elements that can interact with each other.Among the many platforms currently studied (ions, photons, electron spins, to name a few), neutral atoms have the advantage that they can be manipulated with high accuracy, and they are scalable in the sense that many thousands of atoms can be controlled.New experiments by three separate groups have