Two-qubit Quantum Logic Gates for Neutral Atoms Based on the Spin-Flip Blockade*

In the seminal experiment, Jau et al. [1] demonstrated the "spin-flip blockade". Analogous to the "Rydberg blockade", here the spin of one neutral alkali atom in its ground state is allowed to flip between hyperfine manifolds while the two-spins are blockaded from flipping simultaneously due to the additional energy imparted by the light-shift in the presence of Rydberg dressing, due to the dipole-dipole interaction of Rydberg states. This spin-flip blockade was used to demonstrate the generation of Bell states with fidelity >81%. We describe here how to extend this to generate universal two-qubit quantum logic gates. We show that many protocols designed for the optical regime can be translated into the microwave regime and analyze their potential for high-fidelity operation. In comparison to the optical protocols, the microwave Raman lasers afford us ultra-precise control which results in the potential for fast quantum logic gates with reduced noise and low decoherence.