Stern–Gerlach detection of neutral-atom qubits in a state-dependent optical lattice

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.A technique based on the coherent splitting of the atoms’ wavefunctions according to their internal states in an optical lattice allows the measurement of neutral-atom qubits in a three-dimensional array with extremely high fidelity, up to 99.94%.

[1]  Otto Stern,et al.  Der experimentelle Nachweis der Richtungsquantelung im Magnetfeld , 1922 .

[2]  W. Gerlāch,et al.  Der experimentelle Nachweis der Richtungsquantelung im Magnetfeld , 1922 .

[3]  I. H. Deutsch,et al.  Quantum state control in optical lattices , 1998 .

[4]  D. Weiss,et al.  Imaging single atoms in a three dimensional array , 2007 .

[5]  D. Bruß,et al.  Lectures on Quantum Information , 2007 .

[6]  Robert Raussendorf,et al.  Fault-tolerant quantum computation with high threshold in two dimensions. , 2007, Physical review letters.

[7]  G. Rempe,et al.  Lossless state detection of single neutral atoms. , 2010, Physical review letters.

[8]  Tilo Steinmetz,et al.  Cavity-based single atom preparation and high-fidelity hyperfine state readout. , 2010, Physical review letters.

[9]  Daniel Nigg,et al.  Experimental Repetitive Quantum Error Correction , 2011, Science.

[10]  C. Hamley,et al.  Nondestructive fluorescent state detection of single neutral atom qubits. , 2010, Physical review letters.

[11]  A. Browaeys,et al.  Free-space lossless state detection of a single trapped atom. , 2010, Physical review letters.

[12]  Yang Wang,et al.  3D projection sideband cooling. , 2012, Physical review letters.

[13]  M. Mariantoni,et al.  Surface codes: Towards practical large-scale quantum computation , 2012, 1208.0928.

[14]  Daniel Sank,et al.  Fast accurate state measurement with superconducting qubits. , 2014, Physical review letters.

[15]  C. Regal,et al.  Rapid Production of Uniformly Filled Arrays of Neutral Atoms. , 2015, Physical review letters.

[16]  Yang Wang,et al.  Coherent Addressing of Individual Neutral Atoms in a 3D Optical Lattice. , 2015, Physical review letters.

[17]  John M. Martinis,et al.  State preservation by repetitive error detection in a superconducting quantum circuit , 2015, Nature.

[18]  Yang Wang,et al.  Single-qubit gates based on targeted phase shifts in a 3D neutral atom array , 2016, Science.

[19]  M. Saffman.  Quantum computing with atomic qubits and Rydberg interactions: progress and challenges , 2016, 1605.05207.

[20]  S. Debnath,et al.  Demonstration of a small programmable quantum computer with atomic qubits , 2016, Nature.

[21]  I. Bloch,et al.  Spin- and density-resolved microscopy of antiferromagnetic correlations in Fermi-Hubbard chains , 2016, Science.

[22]  Hyosub Kim,et al.  In situ single-atom array synthesis using dynamic holographic optical tweezers , 2016, Nature Communications.

[23]  Eric R. Anschuetz,et al.  Atom-by-atom assembly of defect-free one-dimensional cold atom arrays , 2016, Science.

[24]  W. Alt,et al.  Low-Entropy States of Neutral Atoms in Polarization-Synthesized Optical Lattices. , 2016, Physical review letters.

[25]  W. Alt,et al.  Fast Nondestructive Parallel Readout of Neutral Atom Registers in Optical Potentials. , 2017, Physical review letters.

[26]  M. Saffman,et al.  Parallel Low-Loss Measurement of Multiple Atomic Qubits. , 2017, Physical review letters.

[27]  Kohei Kato,et al.  Site-resolved imaging of single atoms with a Faraday quantum gas microscope , 2016, 1607.07045.

[28]  Quantum computing with neutral atoms , 2017 .

[29]  Caroline Figgatt,et al.  Fault-tolerant quantum error detection , 2016, Science Advances.

[30]  Aishwarya Kumar,et al.  Sorting ultracold atoms in a three-dimensional optical lattice in a realization of Maxwell’s demon , 2018, Nature.

[31]  Aishwarya Kumar,et al.  An omniscient Maxwell's demon , 2018, 1806.02403.

[32]  Antoine Browaeys,et al.  Synthetic three-dimensional atomic structures assembled atom by atom , 2017, Nature.

[33]  A. Cooper,et al.  2000-Times Repeated Imaging of Strontium Atoms in Clock-Magic Tweezer Arrays. , 2018, Physical review letters.