Enhancing qubit readout through dissipative sub-Poissonian dynamics

Abstract

Single-shot qubit readout typically combines high readout contrast with long-lived readout signals, leading to large signal-to-noise ratios and high readout fidelities. In recent years, it has been demonstrated that both readout contrast and readout signal lifetime, and thus the signal-to-noise ratio, can be enhanced by forcing the qubit state to transition through intermediate states. In this work, we demonstrate that the sub-Poissonian relaxation statistics introduced by intermediate states can reduce the single-shot readout error rate by orders of magnitude even when there is no increase in signal-to-noise ratio. These results hold for moderate values of the signal-to-noise ratio ($\mathcal{S}\lesssim 100$) and a small number of intermediate states ($N\lesssim 10$). The ideas presented here could have important implications for readout schemes relying on the detection of transient charge states, such as spin-to-charge conversion schemes for semiconductor spin qubits and parity-to-charge conversion schemes for topologically protected Majorana qubits.

10 pages, 6 figures. Two appendices have been added. This version is close to the final published version

References in corpus (13)

• Single-shot read-out of an individual electron spin in a quantum dot
• High-fidelity projective readout of a solid-state spin quantum register
• High-fidelity preparation, gates, memory and readout of a trapped-ion quantum bit
• Measurement-Only Topological Quantum Computation
• Single-shot qubit readout in circuit Quantum Electrodynamics
• Single-shot qubit readout in circuit Quantum Electrodynamics
• Majorana box qubits
• Efficient readout of a single spin state in diamond via spin-to-charge conversion
• Protocols for optimal readout of qubits using a continuous quantum nondemolition measurement
• Cavity-based single atom preparation and high-fidelity hyperfine state readout
• Bends In Nanotubes Allow Electric Spin Control and Coupling
• Correlations and entanglement of microwave photons emitted in a cascade decay
• Optimal signal processing for continuous qubit readout