Coherent control for qubit state readout

Conrad Roman,Wesley C Campbell,Anthony Ransford,Michael Ip

doi:10.1088/1367-2630/ab9982

Conrad Roman, Wesley C Campbell + Show 2 more

Open Access

https://doi.org/10.1088/1367-2630/ab9982

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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 our quantum state detection of optical-frequency and electron-shelved trapped ion qubits by more than two 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.

Highlights

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
Since these devices are susceptible to information corruption, it is likely some form of quantum error correction will be required to perform even moderately lengthy computations, and repeated qubit state detections will be needed during operation [2]
When an ion qubit is in the bright state, laser-induced fluorescence (LIF) photons are collected by high-NA imaging optics, spatially filtered from the incidental laser scatter, and counted using a photomultiplier tube (PMT)

Summary

Introduction

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. When an ion qubit is in the bright state, laser-induced fluorescence (LIF) photons are collected by high-NA imaging optics, spatially filtered from the incidental laser scatter, and counted using a photomultiplier tube (PMT).

Results

Conclusion