High-Fidelity Indirect Readout of Trapped-Ion Hyperfine Qubits.

We propose and demonstrate a protocol for high-fidelity indirect readout of trapped ion hyperfine qubits, where the state of a ^{9}Be^{+} qubit ion is mapped to a ^{25}Mg^{+} readout ion using laser-driven Raman transitions. By partitioning the ^{9}Be^{+} ground-state hyperfine manifold into two subspaces representing the two qubit states and choosing appropriate laser parameters, the protocol can be made robust to spontaneous photon scattering errors on the Raman transitions, enabling repetition for increased readout fidelity. We demonstrate combined readout and back-action errors for the two subspaces of 1.2_{-0.6}^{+1.1}×10^{-4} and 0_{-0}^{+1.9}×10^{-5} with 68% confidence while avoiding decoherence of spectator qubits due to stray resonant light that is inherent to direct fluorescence detection.

[1]  W. C. Campbell,et al.  Weak dissipation for high-fidelity qubit-state preparation and measurement , 2021, Physical Review A.

[2]  C. Figgatt,et al.  Suppression of midcircuit measurement crosstalk errors with micromotion , 2021, Physical Review A.

[3]  A. M. Meier,et al.  High-Fidelity Bell-State Preparation with ^{40}Ca^{+} Optical Qubits. , 2021, Physical review letters.

[4]  E. Knill,et al.  High-fidelity laser-free universal control of trapped ion qubits , 2021, Nature.

[5]  Scalable hyperfine qubit state detection via electron shelving in the 2D5/2 and 2F7/2 manifolds in 171Yb+ , 2020, Physical Review A.

[6]  A. Bermudez,et al.  Crosstalk Suppression for Fault-tolerant Quantum Error Correction with Trapped Ions , 2020, Quantum.

[7]  V. Verma,et al.  State Readout of a Trapped Ion Qubit Using a Trap-Integrated Superconducting Photon Detector. , 2020, Physical review letters.

[8]  B. Blinov,et al.  High-fidelity simultaneous detection of a trapped-ion qubit register , 2020, Physical Review A.

[9]  C. Figgatt,et al.  Demonstration of the trapped-ion quantum CCD computer architecture , 2020, Nature.

[10]  D. P. Nadlinger,et al.  Benchmarking a High-Fidelity Mixed-Species Entangling Gate. , 2020, Physical review letters.

[11]  R. Blume-Kohout,et al.  Detecting crosstalk errors in quantum information processors , 2019, Quantum.

[12]  Liang Jiang,et al.  High-Fidelity Measurement of Qubits Encoded in Multilevel Superconducting Circuits , 2019, Physical Review X.

[13]  D. Hucul,et al.  High-fidelity manipulation of a qubit enabled by a manufactured nucleus , 2019, npj Quantum Information.

[14]  A. C. Wilson,et al.  Quantum Logic Spectroscopy with Ions in Thermal Motion , 2019, Physical review. X.

[15]  John C. Platt,et al.  Quantum supremacy using a programmable superconducting processor , 2019, Nature.

[16]  Sae Woo Nam,et al.  High-speed low-crosstalk detection of a 171Yb+ qubit using superconducting nanowire single photon detectors , 2019, Communications Physics.

[17]  J. Chiaverini,et al.  Dual-species, multi-qubit logic primitives for Ca+/Sr+ trapped-ion crystals , 2019, npj Quantum Information.

[18]  L. Duan,et al.  Experimental Hamiltonian Learning of an 11-Qubit Solid-State Quantum Spin Register* , 2019, Chinese Physics Letters.

[19]  D. J. Twitchen,et al.  A Ten-Qubit Solid-State Spin Register with Quantum Memory up to One Minute , 2019, Physical Review X.

[20]  John Chiaverini,et al.  Trapped-ion quantum computing: Progress and challenges , 2019, Applied Physics Reviews.

[21]  J. D. Wong-Campos,et al.  Benchmarking an 11-qubit quantum computer , 2019, Nature Communications.

[22]  Emanuel Knill,et al.  Quantum gate teleportation between separated qubits in a trapped-ion processor , 2019, Science.

[23]  A. C. Wilson,et al.  Trapped-Ion Spin-Motion Coupling with Microwaves and a Near-Motional Oscillating Magnetic Field Gradient. , 2018, Physical review letters.

[24]  B. Lanyon,et al.  Observation of entangled states of a fully-controlled 20 qubit system , 2017, 1711.11092.

[25]  T. R. Tan,et al.  High-Fidelity Universal Gate Set for ^{9}Be^{+} Ion Qubits. , 2016, Physical review letters.

[26]  N. Linke,et al.  High-Fidelity Quantum Logic Gates Using Trapped-Ion Hyperfine Qubits. , 2015, Physical review letters.

[27]  Ting Rei Tan,et al.  High-Fidelity Entangling Gates with Trapped-Ions , 2016 .

[28]  R. Bowler,et al.  Multi-element logic gates for trapped-ion qubits , 2015, Nature.

[29]  Y Lin,et al.  Sympathetic electromagnetically-induced-transparency laser cooling of motional modes in an ion chain. , 2013, Physical review letters.

[30]  C. Monroe,et al.  Scaling the Ion Trap Quantum Processor , 2013, Science.

[31]  K. R. Brown,et al.  Microwave quantum logic gates for trapped ions , 2011, Nature.

[32]  E. Knill,et al.  Single-qubit-gate error below 10 -4 in a trapped ion , 2011, 1104.2552.

[33]  D. M. Lucas,et al.  Scalable simultaneous multiqubit readout with 99.99% single-shot fidelity , 2009, 0906.3304.

[34]  D M Lucas,et al.  High-fidelity readout of trapped-ion qubits. , 2008, Physical review letters.

[35]  D. Wineland,et al.  High-fidelity adaptive qubit detection through repetitive quantum nondemolition measurements. , 2007, Physical review letters.

[36]  C Langer,et al.  Spectroscopy Using Quantum Logic , 2005, Science.

[37]  David J. Wineland,et al.  Building Blocks for a Scalable Quantum Information Processor Based On Trapped Ions , 2003 .

[38]  C. Monroe,et al.  Architecture for a large-scale ion-trap quantum computer , 2002, Nature.

[39]  F. Mintert,et al.  Ion-trap quantum logic using long-wavelength radiation. , 2001, Physical review letters.

[40]  F. Schmidt-Kaler,et al.  Experimental demonstration of ground state laser cooling with electromagnetically induced transparency. , 2000, Physical review letters.

[41]  K. Mølmer,et al.  QUANTUM COMPUTATION WITH IONS IN THERMAL MOTION , 1998, quant-ph/9810039.

[42]  C. Monroe,et al.  Experimental Issues in Coherent Quantum-State Manipulation of Trapped Atomic Ions , 1997, Journal of research of the National Institute of Standards and Technology.

[43]  H. Dehmelt,et al.  Doppler-free optical spectroscopy on the Ba+ mono-ion oscillator , 1985 .

[44]  E. S. Pearson,et al.  THE USE OF CONFIDENCE OR FIDUCIAL LIMITS ILLUSTRATED IN THE CASE OF THE BINOMIAL , 1934 .