Repetitive readout and real-time control of nuclear spin qubits in ${}^{171}$Yb atoms

Abstract

We demonstrate high fidelity repetitive projective measurements of nuclear spin qubits in an array of neutral ytterbium-171 (${}^{171}$Yb) atoms. We show that the qubit state can be measured with a fidelity of 0.995(4) under a condition that leaves it in the state corresponding to the measurement outcome with a probability of 0.993(6) for a single tweezer and 0.981(4) averaged over the array. This is accomplished by near-perfect cyclicity of one of the nuclear spin qubit states with an optically excited state under a magnetic field of $B=58$ G, resulting in a bright/dark contrast of $\approx 10^5$ during fluorescence readout. The performance improves further as $\sim 1/B^2$. The state-averaged readout survival of 0.98(1) is limited by off-resonant scattering to dark states and can be addressed via post-selection by measuring the atom number at the end of the circuit, or during the circuit by performing a measurement of both qubit states. We combine projective measurements with high-fidelity rotations of the nuclear spin qubit via an AC magnetic field to explore several paradigmatic scenarios, including the non-commutivity of measurements in orthogonal bases, and the quantum Zeno mechanism in which measurements "freeze" coherent evolution. Finally, we employ real-time feedforward to repetitively deterministically prepare the qubit in the $+z$ or $-z$ direction after initializing it in an orthogonal basis and performing a projective measurement in the $z$-basis. These capabilities constitute an important step towards adaptive quantum circuits with atom arrays, such as in measurement-based quantum computation, fast many-body state preparation, holographic dynamics simulations, and quantum error correction.

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Cited by in corpus (31)

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• Coherent Control of the Fine-Structure Qubit in a Single Alkaline-Earth Atom
• Enhanced quantum control of individual ultracold molecules using optical tweezer arrays
• Long-Lived Circular Rydberg Qubits of Alkaline-Earth Atoms in Optical Tweezers
• Fine-Structure Qubit Encoded in Metastable Strontium Trapped in an Optical Lattice
• Computational Capabilities and Compiler Development for Neutral Atom Quantum Processors: Connecting Tool Developers and Hardware Experts
• A scaled local gate controller for optically addressed qubits
• Optimized measurement-free and fault-tolerant quantum error correction for neutral atoms
• Parallelized telecom quantum networking with a ytterbium-171 atom array
• An architecture for two-qubit encoding in neutral ytterbium-171 atoms
• Quantum memory at nonzero temperature in a thermodynamically trivial system
• Fast entangling gates for Rydberg atoms via resonant dipole-dipole interaction
• Leveraging Qubit Loss Detection in Fault Tolerant Quantum Algorithms
• Realization of a crosstalk-free two-ion node for long-distance quantum networking
• High-fidelity and robust controlled-Z gates implemented with Rydberg atoms via echoing rapid adiabatic passage
• Probing curved spacetime with a distributed atomic processor clock
• Microsecond-scale high-survival and number-resolved detection of ytterbium atom arrays
• Fast nuclear-spin entangling gates compatible with large-scale atomic arrays
• Single-atom imaging of ${}^{173}$Yb in optical tweezers loaded by a five-beam magneto-optical trap
• Determining the ${}^3$P${}_0$ excited-state tune-out wavelength of ${}^{174}$Yb in a triple-magic lattice
• Optical nuclear electric resonance as single qubit gate for trapped neutral atoms
• Three-qubit encoding in ytterbium-171 atoms for simulating 1+1D QCD
• Differential polarizability at 1064 nm of the strontium intercombination transition
• Tailoring interaction ranges in atom arrays
• Single Qudit Control in ${}^{87}$Sr via Optical Nuclear Electric Resonance
• Multiqubit Rydberg Gates for Quantum Error Correction
• Laser cooling and qubit measurements on a forbidden transition in neutral Cs atoms
• Universal quantum computation via scalable measurement-free error correction