How to measure Leggett-Garg inequalities with many qubits
The Leggett-Garg inequality (LGI) is a "Bell inequality in time", derived assuming macroscopic realism ("the moon is there, even if I don't look at it") and noninvasive measurability (the system can be measured without the measurement changing the system). The LGI is an important tool for investigating whether quantum effects are tangible in macroscopic systems. In this work, we investigate optimal LGI measurement strategies for experiments with large ensembles of qubits that are subject to noise.
Leggett–Garg inequality violations with a large ensemble of qubits
Neill Lambert, Kamanasish Debnath, Anton Frisk Kockum, George C. Knee, William J. Munro, and Franco Nori
arXiv:1604.04059