Fast and efficient detection of the qubit state in trapped ion systems is critical for implementing quantum error correction and performing fundamental tests such as a loophole-free Bell test. In this work we present a simple qubit state detection protocol for a (171)Yb+ hyperfine atomic qubit trapped in a microfabricated surface trap, enabled by high collection efficiency of the scattered photons and low background photon count rate. We demonstrate average detection times of 10.5, 28.1, and 99.8 μs, corresponding to state detection fidelities of 99%, 99.856(8)%, and 99.915(7)%, respectively.
Qubits used in quantum computing suffer from errors, either from the qubit interacting with the environment, or from imperfect quantum logic gates. Effective quantum error correcting codes require a high fidelity readout of ancilla qubits from which the error syndrome can be determined without affecting data qubits. Here, we present a detection scheme for 171 Yb + qubits, where we use superconducting nanowire single photon detectors and utilize photon time-of-arrival statistics to improve the fidelity and speed. Qubit shuttling allows for creating a separate detection region where an ancilla qubit can be measured without disrupting a data qubit. We achieve an average qubit state detection time of 11 µs with a fidelity of 99.931(6) %. The detection crosstalk error, defined as the probability that the data qubit coherence is lost due to the process of detecting an ancilla qubit, is reduced to ∼2×10 −5 by creating a separation of 370 µm between them.
The fidelity of laser-driven quantum logic operations on trapped ion qubits tend to be lower than microwavedriven logic operations due to the difficulty of stabilizing the driving fields at the ion location. Through stabilization of the driving optical fields and use of composite pulse sequences, we demonstrate high-fidelity single-qubit gates for the hyperfine qubit of a 171 Yb + ion trapped in a microfabricated surface-electrode ion trap. Gate error is characterized using a randomized benchmarking protocol and an average error per randomized Clifford group gate of 3.6(3) × 10 −4 is measured. We also report experimental realization of palindromic pulse sequences that scale efficiently in sequence length. The trapped atomic ion qubits feature desirable properties for use in a quantum computer such as long coherence times [1], high-fidelity qubit measurement [2], and universal logic gates [3]. The quality of quantum logic gate operations on trapped ion qubits has been limited by the stability of the control fields at the ion location used to implement the gate operations. For this reason, the logic gates utilizing microwave fields [4][5][6][7] have shown gate fidelities several orders of magnitude better than those using laser fields [8][9][10]. The laser beams used to drive either Raman gates for a hyperfine ion qubit or optical gates between metastable qubit states are subject to severe wave-front distortion in air due to turbulence, leading to amplitude and phase fluctuations of the optical field at the ion location that limited the gate fidelity in the 0.5% range [8,11].Microfabricated surface-electrode ion traps, where atomic ions are trapped above a two-dimensional surface of electrodes, can provide a scalable platform on which to build an ion-based quantum computer [12,13]. Experiments using surface traps have demonstrated coherence times of more than 1 s [14], state detection with fidelities greater than 99.9% [2], and low-error single-qubit gates [ 2.0(2) × 10 −5 ] using integrated microwave waveguides [4,7]. Use of high-power UV lasers close to the trap surface can lead to substantial charging due to unwanted exposure [15]. The recent development of single-mode fibers capable of delivering high-power UV laser beams [16] opens the possibility of significantly reducing the free-space UV beam path length and delivering a clean spatial mode to the ions, eliminating unwanted scattering off nearby trap structures.Here we demonstrate low-error single-qubit gates performed using stimulated Raman transitions on an ion qubit trapped in a microfabricated chip trap. Gate errors are measured using a randomized benchmarking protocol [8,17,18], where amplitude error in the control beam is compensated using various pulse sequence techniques [19,20]. Using B2 compensation [19], we demonstrate single-qubit gates with an average error per randomized Clifford group gate of 3.6(3) × 10 −4 . We also show that compact palindromic pulse compensation sequences (PDn) [20] compensate for amplitude errors as designed. Two hyperfin...
We report the observation of normal-mode splitting of the atom-cavity dressed states in both the fluorescence and transmission spectra for large atom number and observe subnatural linewidths in this regime. We also implement a method of utilizing the normal-mode splitting to observe Rabi oscillations on the 87 Rb ground state hyperfine clock transition. We demonstrate a large collective cooperativity, C = 1.2ϫ 10 4 , which, in combination with large atom number, N ϳ 2 ϫ 10 5 , offers the potential to realize an absolute phase sensitivity better than that achieved by state-of-the-art atomic fountain clocks or inertial sensors operating near the quantum projection noise limit.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.