Demonstration of a Neutral Atom Controlled-NOT Quantum Gate

We present the first demonstration of a CNOT gate between two individually addressed neutral atoms. Our implementation of the CNOT uses Rydberg blockade interactions between neutral atoms held in optical traps separated by $>8\mu \mathrm{m}$. Using two different gate protocols we measure CNOT fidelities of $F=0.73$ and 0.72 based on truth table probabilities. The gate was used to generate Bell states with fidelity $F=0.48\pm 0.06$. After correcting for atom loss we obtain an a posteriori entanglement fidelity of $F=0.58$.

Figure 1

CNOT gate protocols using Hadamard—$C_Z$ (center) and controlled amplitude swap (right). All pulses are $\pi$ pulses except where indicated otherwise.

Figure 2

(a) Experimental geometry, (b) laser excitation frequencies, and (c) CNOT sequence. See text for details.

Figure 3

Measured probabilities for (a) state preparation, (b) AS-CNOT, (c) $H\mathrm{\text{−}}{C}_Z$ CNOT and (d) output states of the $H\mathrm{\text{−}}{C}_Z$ CNOT under variation of the relative phase of the $\pi /2$ pulses. The reported matrices are based on an average of at least 100 data points for each matrix element and the error bars are $\pm 1$ standard deviation.

Figure 4

Measured probabilities for preparation of Bell states $|B_1⟩$, $|B_2⟩$ using AS-CNOT (left) and $H\mathrm{\text{−}}{C}_Z$ CNOT (right). The parity oscillation data were obtained from $|B_1⟩$ with the $H\mathrm{\text{−}}{C}_Z$ CNOT.