Fig. 4: Time-bin qubits fidelity measurement.
From: Elimination of noise in optically rephased photon echoes
a The pulse sequence for the preparation and analysis of time-bin qubits. The time difference between \(\left|e\right\rangle\) and \(\left|l\right\rangle\) is Δt, and the relative phase is controlled as Δφ1. After three π pulses that are the same as that required in standard NLPE, two \({(\frac{\pi }{2})}_{35}\) are employed to read out each input twice. The time difference between two \({(\frac{\pi }{2})}_{35}\) is also Δt, and the relative phase is controlled as Δφ2. b Storage performances for four input qubit states. The average photon number per qubit is 2.29 photons. For input states \(\left|e\right\rangle\) and \(\left|l\right\rangle\), the output is projected on \(\left|e\right\rangle\) and \(\left|l\right\rangle\). For input superposition states (\(\left|e\right\rangle +\left|l\right\rangle\) and \(\left|e\right\rangle +i\left|l\right\rangle\)), the output is projected superposition states, which generate the maximal interference and minimal interference results in the middle output bin. Photon-counting histograms can be found in Supplementary Fig. 2 and the experiments are repeated for 20,000 trials. The error bars represent one standard deviation of photon counts assuming Poissonian photon statistics.
