Weak values and the Leggett-Garg inequality in solid-state qubits

TL;DR

This paper explores the relationship between weak values and Leggett-Garg inequality violations in solid-state qubits, demonstrating that non-classical weak values coincide with quantum violations of macrorealism.

Contribution

It establishes a connection between weak values and Leggett-Garg inequality violations in solid-state qubits, including generalized weak values and their classical bounds.

Findings

Weak values can be non-classical only if Leggett-Garg inequality is violated.

Generalized weak values are described with post-selection on a range of results.

Analysis uses kicked quantum nondemolition measurements on a double-dot charge qubit.

Abstract

An implementation of weak values is investigated in solid-state qubits. We demonstrate that a weak value can be non-classical if and only if a Leggett-Garg inequality can also be violated. Generalized weak values are described, where post-selection on a range of weak measurement results. Imposing classical weak values permits the derivation of Leggett-Garg inequalities for bounded operators. Our analysis is presented in terms of kicked quantum nondemolition measurements on a quantum double-dot charge qubit.