- White, TC;
- Mutus, JY;
- Dressel, J;
- Kelly, J;
- Barends, R;
- Jeffrey, E;
- Sank, D;
- Megrant, A;
- Campbell, B;
- Chen, Yu;
- Chen, Z;
- Chiaro, B;
- Dunsworth, A;
- Hoi, I-C;
- Neill, C;
- O’Malley, PJJ;
- Roushan, P;
- Vainsencher, A;
- Wenner, J;
- Korotkov, AN;
- Martinis, John M
Abstract:
Weak measurement has provided new insight into the nature of quantum measurement, by demonstrating the ability to extract average state information without fully projecting the system. For single-qubit measurements, this partial projection has been demonstrated with violations of the Leggett–Garg inequality. Here we investigate the effects of weak measurement on a maximally entangled Bell state through application of the Hybrid Bell–Leggett–Garg inequality (BLGI) on a linear chain of four transmon qubits. By correlating the results of weak ancilla measurements with subsequent projective readout, we achieve a violation of the BLGI with 27 s.d.s. of certainty.