Atoms Talking with SQUIDs

Recent proposals in quantum computing have centered on the creation of hybrid quantum processors [1]. Here we present a scheme to inductively couple a cloud of $^{87}$Rb atoms to a superconducting flux qubit. Conveniently, the flux qubit can be tuned to have the same energy level separation as the 6.8GHz hyperfine splitting in $^{87}$Rb. We will trap the atoms around a sub-wavelength optical fiber using a two-color, evanescent wave dipole trap [2]. This will allow us to bring the atoms less than 10$\mu$m above the superconductor's surface without producing excessive heating or changing magnetic fields. In addition to interfacing a stable quantum memory ($^{87}$Rb atoms) with a fast, scalable quantum processor (flux qubit), this setup lends itself to probing sources of decoherence in superconducting qubits.\\[4pt] [1] M. Wallquist \textit{et al.}, Phys. Scr. T137, 014001 (2009).\\[0pt] [2] F. L. Kien \textit{et al.}, Phys. Rev. A 70, 063403 (2004).