Figure 5
From: Implementation of leakage elimination operators and subspace protection
Curves fitted to the fidelity of quantum states measured at different times, corresponding to up to 600 pulses, with 1024 shots at each time. The blue curves correspond to the run where LEO pulses where applied, and have been fitted with Eq. (11) for (a,c,e) and Eq. (12) for (b,d,f). The red curves correspond to the freely evolving systems and have all been fitted with the exponential function in (12). (a,b) Show the evolution of a two-qubit system, with inital state \(|{\Psi _{2}}\rangle =(|{01}\rangle +|{10}\rangle )/\sqrt{2}\) and Z pulses used as an LEO, with (b) having identity pulses applied between LEO applications; (c,d) depict the three-qubit case that also uses Z as an LEO, with initial state \(|{\Psi _{3}}\rangle =(|{001}\rangle +|{010}\rangle +|{100}\rangle +|{111}\rangle )/2\), again, (d) has had identity pulses applied between LEO applications. In (e,f) we used \(|{\Phi }\rangle =(|{10}\rangle -|{11}\rangle )/\sqrt{2}\) as our initial state and the role of LEO was carried out by CNOT gates, having identity pulses applied between LEO applications for (f).
