Coherent control for qubit state readout

Abstract

Short pulses from mode-locked lasers can produce background-free atomic fluorescence by allowing temporal separation of the prompt incidental scatter from the subsequent atomic emission. We use this to improve quantum state detection of optical-frequency and electron-shelved trapped ion qubits by more than 2 orders of magnitude. For direct detection of qubits defined on atomic hyperfine structure, however, the large bandwidth of short pulses is greater than the hyperfine splitting, and repeated excitation is not qubit state selective. Here, we show that the state resolution needed for projective quantum measurement of hyperfine qubits can be recovered by applying techniques from coherent control to the orbiting valence electron of the queried ion. We demonstrate electron wavepacket interference to allow readout of the original qubit state using broadband pulses, even in the presence of large amounts of background laser scatter.

7 pages, 3 figures

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Cited by in corpus (8)

• A Site-Resolved 2D Quantum Simulator with Hundreds of Trapped Ions
• Realizing coherently convertible dual-type qubits with the same ion species
• Scalable hyperfine qubit state detection via electron shelving in the ${}^2$D${}_{5/2}$ and ${}^2$F${}_{7/2}$ manifolds in ${}^{171}$Yb${}^{+}$
• Weak dissipation for high fidelity qubit state preparation and measurement
• Individually Addressed Entangling Gates in a Two-Dimensional Ion Crystal
• High-resolution laser-induced fluorescence spectroscopy of ${}^{28}$Si${}^{16}$O${}^{+}$ and ${}^{29}$Si${}^{16}$O${}^{+}$ in a cryogenic buffer-gas cell
• Hamiltonian learning for 300 trapped ion qubits with long-range couplings
• Ultrafast coherent excitation of an Ytterbium ion with single laser pulses