Extended Data Fig. 1: Atomic-level diagram and pulse sequence. | Nature

Extended Data Fig. 1: Atomic-level diagram and pulse sequence.

From: High-fidelity parallel entangling gates on a neutral-atom quantum computer

Extended Data Fig. 1: Atomic-level diagram and pulse sequence.The alternative text for this image may have been generated using AI.

a, Level diagram showing key levels of 87Rb used in our quantum circuits. The clock states, |0⟩ and |1⟩, are the qubit states used in this work. Excitation to the Rydberg state between |1⟩ and |r⟩ is carried out by a two-photon transition driven by 420-nm and 1,013-nm lasers. Single-qubit rotations are realized with an amplitude-modulated 795-nm laser that drives Raman rotations between the mF = 0 clock states. A DC magnetic field of 8.5 G is applied throughout this work. The Rydberg detuning signs and polarization signs are carefully selected for various optimizations: for suppressing 420-induced differential light shift between |0⟩ and |1⟩, we red-detuned the 6P3/2 transition; for using dark-state physics (nominally the phase profile corresponds to a certain sign of two-photon detuning), we thereby choose positive two-photon detuning, which—in turn—then suppresses coupling to mJ = − 1/2 by being primarily on the upper side of mJ = +1/2; and, finally, the 1,013-nm light shift is lower (by about 30%) at this single-photon detuning sign, as there is a magic wavelength of about 1 GHz red-detuned of 6P3/2 for the |1⟩ → 53S1/2 transition98. Two downsides of this detuning choice are that this choice of 420-nm polarization and detuning causes a vector light shift in the hyperfine ground-state manifold that causes the mF levels to be pushed closer together, as opposed to further apart, which could exacerbate effects arising from 420-induced vector light shifts coupling adjacent mF states in the ground-state manifold (although negligible here), and the other downside is that the mJ = −1/2 Rydberg pair states are closer detuned to the two-photon excitation and so we require a larger interaction strength to suppress their excitation, although the matrix element to these states is smaller. b, Example pulse sequence, here for making a \(\left|{\Phi }^{+}\right\rangle \) Bell state between two qubits. Traps are pulsed off for a few hundred ns during the Rydberg gate to avoid both antitrapping of the Rydberg state and inhomogeneous light shifts that broaden the transition, and the ground-state atoms are then recaptured for roughly 3 μs between consecutive gate applications.

Back to article page