More Like this

1. Hamiltonian engineering of spin-orbit coupled fermions in a Wannier-Stark optical lattice clock

   https://doi.org/10.48550/arXiv.2201.05909  

   Aeppli, A.; Chu, A.; Bothwell, T.; Kennedy, C.J.; Kedar, D.; He, P.; Rey, A.M.; Ye, J. (July 2022, ArXivorg)

   Engineering a Hamiltonian system with tunable interactions provides opportunities to optimize performance for quantum sensing and explore emerging phenomena of many-body systems. An optical lattice clock based on partially delocalized Wannier-Stark states in a gravity-tilted shallow lattice supports superior quantum coherence and adjustable interactions via spin-orbit coupling, thus presenting a powerful spin model realization. The relative strength of the on-site and off-site interactions can be tuned to achieve a zero density shift at a `magic' lattice depth. This mechanism, together with a large number of atoms, enables the demonstration of the most stable atomic clock while minimizing a key systematic uncertainty related to atomic density. Interactions can also be maximized by driving off-site Wannier-Stark transitions, realizing a ferromagnetic to paramagnetic dynamical phase transition. 

   more » « less
2. Prospects of a thousand-ion Sn2+ Coulomb-crystal clock with sub-10−19 inaccuracy

   https://doi.org/10.1038/s41467-024-49241-w  

   Leibrandt, David_R; Porsev, Sergey_G; Cheung, Charles; Safronova, Marianna_S (July 2024, Nature Communications)

   Abstract Optical atomic clocks are the most accurate and precise measurement devices of any kind, enabling advances in international timekeeping, Earth science, fundamental physics, and more. However, there is a fundamental tradeoff between accuracy and precision, where higher precision is achieved by using more atoms, but this comes at the cost of larger interactions between the atoms that limit the accuracy. Here, we propose a many-ion optical atomic clock based on three-dimensional Coulomb crystals of order one thousand Sn²⁺ions confined in a linear RF Paul trap with the potential to overcome this limitation. Sn²⁺has a unique combination of features that is not available in previously considered ions: a¹S₀ ↔ ³P₀clock transition between two states with zero electronic and nuclear angular momentum (I = J = F = 0) making it immune to nonscalar perturbations, a negative differential polarizability making it possible to operate the trap in a manner such that the two dominant shifts for three-dimensional ion crystals cancel each other, and a laser-accessible transition suitable for direct laser cooling and state readout. We present calculations of the differential polarizability, other relevant atomic properties, and the motion of ions in large Coulomb crystals, in order to estimate the achievable accuracy and precision of Sn²⁺Coulomb-crystal clocks. 

   more » « less
3. Increased atom-cavity coupling through cooling-induced atomic reorganization

   https://doi.org/10.1103/PhysRevResearch.6.L032049  

   Shu, Chi; Colombo, Simone; Li, Zeyang; Adiyatullin, Albert; Mendez, Enrique; Pedrozo-Peñafiel, Edwin; Vuletić, Vladan (September 2024, Physical Review Research)

   The strong coupling of atoms to optical cavities can improve optical lattice clocks as the cavity enables metrologically useful collective atomic entanglement and high-fidelity measurement. To this end, it is necessary to cool the ensemble to suppress motional broadening, and advantageous to maximize and homogenize the atom-cavity coupling. We demonstrate resolved Raman sideband cooling via the cavity as a method that can simultaneously achieve both goals. In 200 ms of Raman sideband cooling, we cool ${}^{171}\mathrm{Yb}$atoms to an average vibration number $\langle n_x\rangle =0.23\left(7\right)$in the tightly binding direction, resulting in $93\%$optical $\pi$-pulse fidelity on the clock transition ${}^{1}S_0\to {}^{3}P_0$. During cooling, the atoms self-organize into locations with maximal atom-cavity coupling, which will improve quantum metrology applications. Published by the American Physical Society2024 

   more » « less
4. Long-lived Bell states in an array of optical clock qubits

   https://doi.org/10.48550/arXiv.2111.14653  

   Schine, N.; Young, A.W.; Eckner, W.J.; Martin, M. J.; Kaufman, A. M. (July 2022, ArXivorg)

   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⟩=12√(|gg⟩+i|ee⟩), with a fidelity of 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 τbc=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. 

   more » « less
5. Measuring gravitational attraction with a lattice atom interferometer

   https://doi.org/10.1038/s41586-024-07561-3  

   Panda, Cristian D; Tao, Matthew J; Ceja, Miguel; Khoury, Justin; Tino, Guglielmo M; Müller, Holger (July 2024, Nature)

   Despite being the dominant force of nature on large scales, gravity remains relatively elusive to precision laboratory experiments. Atom interferometers are powerful tools for investigating, for example, Earth’s gravity, the gravitational constant, deviations from Newtonian gravity and general relativity. However, using atoms in free fall limits measurement time to a few seconds, and much less when measuring interactions with a small source mass. Recently, interferometers with atoms suspended for 70 s in an optical-lattice mode filtered by an optical cavity have been demonstrated. However, the optical lattice must balance Earth’s gravity by applying forces that are a billionfold stronger than the putative signals, so even tiny imperfections may generate complex systematic effects. Thus, lattice interferometers have yet to be used for precision tests of gravity. Here we optimize the gravitational sensitivity of a lattice interferometer and use a system of signal inversions to suppress and quantify systematic efects. We measure the attraction of a miniature source mass to be amass = 33.3 ± 5.6stat ± 2.7syst nm s−2, consistent with Newtonian gravity, ruling out ‘screened ffth force’ theories3,15,16 over their natural parameter space. The overall accuracy of 6.2 nm s−2 surpasses by more than a factor of four the best similar measurements with atoms in free fall. Improved atom cooling and tilt-noise suppression may further increase sensitivity for investigating forces at sub-millimetre ranges, compact gravimetry, measuring the gravitational Aharonov–Bohm effect and the gravitational constant, and testing whether the gravitational field has quantum properties. 

   more » « less