Qubit state measurements are an essential part of any quantum computer, constituting the readout. Accurate measurements are also an integral component of one-way quantum computation and of error correction, which is needed for fault-tolerant quantum computation1. Here, we present a state measurement for neutral-atom qubits based on coherent spatial splitting of the atoms’ wavefunctions. It is reminiscent of the Stern–Gerlach experiment2, but carried out in light traps. For around 160 qubits in a three-dimensional array, we achieve a measurement fidelity of 0.9994, which is roughly 20 times lower error than in previous measurements of neutral-atom arrays3,4. It also greatly exceeds the measurement fidelity of other arrays with more than four qubits, including those with ion and superconducting qubits5,6. Our measurement fidelity is essentially independent of the number of qubits measured, and since the measurement causes no loss, we can reuse the atoms. We also demonstrate that we can replace atoms lost to background gas collisions during the experiment7.
Subscribe to Journal
Get full journal access for 1 year
only $14.08 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
The data that support the plots in this paper are available from the corresponding author upon reasonable request.
Bruss, D. & Leuchs, G. Lectures on Quantum Information (Wiley, 2007).
Gerlach, W. & Stern, O. Der experimentelle Nachweis der Richtungsquantelung im Magnetfeld. Z. Phys. 9, 349–352 (1922).
Kwon, M., Ebert, M. F., Walker, T. G. & Saffman, M. Parallel low-loss measurement of multiple atomic qubits. Phys. Rev. Lett. 119, 180504 (2017).
Martinez-Dorantes, M. et al. Fast nondestructive parallel readout of neutral atom registers in optical potentials. Phys. Rev. Lett. 119, 180503 (2017).
Debnath, S. et al. Demonstration of a small programmable quantum computer with atomic qubits. Nature 536, 63–66 (2016).
Jeffrey, E. et al. Fast accurate state measurement with superconducting qubits. Phys. Rev. Lett. 112, 190504 (2014).
Kumar, A., Wu, T.-Y., Giraldo Mejia, F. & Weiss, D. S. Sorting ultracold atoms in a 3D optical lattice in a realization of Maxwell’s demon. Nature 561, 83–87 (2018).
Weiss, D. & Saffman, M. Quantum computing with neutral atoms. Phys. Today 70, 45–50 (2017).
Nelson, K. D., Li, X. & Weiss, D. S. Imaging single atoms in a three-dimensional array. Nat. Phys. 3, 556–560 (2007).
Gibbons, M. J., Hamley, C. D., Shih, C. Y. & Chapman, M. S. Nondestructive fluorescent state detection of single neutral atom qubits. Phys. Rev. Lett. 106, 133002 (2011).
Fuhrmanek, A., Bourgain, R., Sortais, Y. R. P. & Browaeys, A. Free-space lossless state detection of a single trapped atom. Phys. Rev. Lett. 106, 133003 (2011).
Covey, J. P., Madjarov, I. S., Cooper, A. & Endres, M. 2000-times repeated imaging of strontium atoms in clock-magic tweezer arrays. Preprint at https://arxiv.org/abs/1811.06014 (2018).
Bochmann, J. et al. Lossless state detection of single neutral atoms. Phys. Rev. Lett. 104, 203601 (2010).
Gehr, R. et al. Cavity-based single atom preparation and high-fidelity hyperfine state readout. Phys. Rev. Lett. 104, 203602 (2010).
Boll, M. et al. Spin- and density-resolved microscopy of antiferromagnetic correlations in Fermi-Hubbard chains. Science 353, 1257–1260 (2016).
Deutsch, I. H. & Jessen, P. S. Quantum-state control in optical lattices. Phys. Rev. A 57, 1972–1986 (1998).
Robens, C. et al. Low-entropy states of neutral atoms in polarization-synthesized optical lattices. Phys. Rev. Lett. 118, 065302 (2017).
Li, X., Corcovilos, T. A., Wang, Y. & Weiss, D. S. 3D projection sideband cooling. Phys. Rev. Lett. 108, 103001 (2012).
Wang, Y., Zhang, X. L., Corcovilos, T. A., Kumar, A. & Weiss, D. S. Coherent addressing of individual neutral atoms in a 3D optical lattice. Phys. Rev. Lett. 115, 043003 (2015).
Wang, Y., Kumar, A., Wu, T. Y. & Weiss, D. S. Single-qubit gates based on targeted phase shifts in a 3D neutral atom array. Science 352, 1562–1565 (2016).
Barredo, D., Lienhard, V., De Leseleuc, S., Lahaye, T. & Browaeys, A. Synthetic three-dimensional atomic structures assembled atom by atom. Nature 561, 79–82 (2018).
Endres, M. et al. Atom-by-atom assembly of defect-free one-dimensional cold atom arrays. Science 354, 1024–1027 (2016).
Kim, H. et al. In situ single-atom array synthesis using dynamic holographic optical tweezers. Nat. Commun. 7, 13317 (2016).
Lester, B. J., Luick, N., Kaufman, A. M., Reynolds, C. M. & Regal, C. A. Rapid production of uniformly filled arrays of neutral atoms. Phys. Rev. Lett. 115, 073003 (2015).
Schindler, P. et al. Experimental repetitive quantum error correction. Science 332, 1059–1061 (2011).
Linke, N. M. et al. Fault-tolerant quantum error detection. Sci. Adv. 3, e1701074 (2017).
Kelly, J. et al. State preservation by repetitive error detection in a superconducting quantum circuit. Nature 519, 66–69 (2015).
Yamamoto, R. et al. Site-resolved imaging of single atoms with a Faraday quantum gas microscope. Phys. Rev. A 96, 033610 (2017).
Saffman, M. Quantum computing with atomic qubits and Rydberg interactions: progress and challenges. J. Phys. B 49, 202001 (2016).
Fowler, A. G., Mariantoni, M., Martinis, J. M. & Cleland, A. N. Surface codes: towards practical large-scale quantum computation. Phys. Rev. A 86, 032324 (2012).
Raussendorf, R. & Harrington, J. Fault-tolerant quantum computation with high threshold in two dimensions. Phys. Rev. Lett. 98, 190504 (2007).
This work was supported by US National Science Foundation grant numbers PHY-1520976 and PHY-1820849.
The authors declare no competing interests.
Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
Wu, T., Kumar, A., Giraldo, F. et al. Stern–Gerlach detection of neutral-atom qubits in a state-dependent optical lattice. Nat. Phys. 15, 538–542 (2019). https://doi.org/10.1038/s41567-019-0478-8