Quantum efficiency of binary-outcome detectors of solid-state qubits

TL;DR

This paper analyzes the quantum efficiency of various binary-outcome solid-state qubit detectors, emphasizing models like indirect projective, linear, superconducting phase qubit, and tunneling detectors, especially for quantum non-demolition measurements.

Contribution

It provides a comprehensive analysis of quantum efficiency definitions and evaluates several detector models for solid-state qubits, focusing on quantum non-demolition measurements.

Findings

Quantum efficiency varies across different detector models.

Superconducting phase qubit detectors show specific efficiency characteristics.

Tunneling-based detectors offer unique advantages in certain regimes.

Abstract

We discuss definitions of the quantum efficiency for binary-outcome qubit detectors with imperfect fidelity, focusing on the subclass of quantum non-demolition detectors. Quantum efficiency is analyzed for several models of detectors, including indirect projective measurement, linear detector in binary-outcome regime, detector of the superconducting phase qubit, and detector based on tunneling into continuum.